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[Display omitted] • A novel double perovskite oxides NCBCC are studied as oxygen electrodes for RSOCs. • Introduction of Ca significantly reduces the TEC and increases the conductivity. • Co-doping with Ca2+ leads to good stability at high oxygen partial pressure. • NCBC exhibits excellent reversibility and catalysis in opposite operating mode. The oxygen electrode of the solid oxide cells (SOCs) operates under an oxidizing atmosphere. Lattice shrinkage in a high oxygen partial pressure environment results in cation misalignment, leading to a decline in performance. Addressing the drawbacks associated with A-site cation mismatch in LnBaCo 2 O 5+ δ double perovskite oxides for reversible solid oxide cells (RSOCs) oxygen electrodes, a novel calcium ion co-doping strategy is proposed. This approach effectively mitigates A-site cation segregation and enhances stability. The glycine-nitrate method was employed to synthesize Nd 0.8 Ca 0.2 Ba 1− x Ca x Co 2 O 5+ δ (x = 0–0.2) layered double perovskites oxides co-doped with calcium ions, denoted as NCBCC. NCBCC exhibits excellent compatibility with commonly used electrolytes. The doping of calcium co-doped in NdBaCo 2 O 5+ δ decreases the thermal expansion coefficient and improves the electron transfer characteristics. The sample with x = 0.1 exhibited an area-specific resistance (ASR) of 0.024 Ω cm2 when operated at a temperature of 800 °C in air. In the solid oxide fuel cell mode, employing x = 0.1 as an oxygen electrode, the maximum power density achieved was 766 mW cm−2 at 800 °C. In the solid oxide electrolysis cell mode, operating with CO 2 and steam at an electrolysis voltage of 1.5 V and a temperature of 800 °C, the corresponding current densities were −1.51 and −1.85 A cm−2, respectively. The incorporation of calcium ions into layered perovskite oxides offers a promising strategy to enhance the performance of oxygen electrodes in RSOCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Analyzed physical and chemical properties and performed quantitative phase analysis of HAHCA at different coal combustion temperatures. • Clarified the relation between the leaching behavior of 28 valuable elements and coal combustion temperatures under acidic and alkaline conditions. • Most metals easily leached from HAHCA under acidic conditions when coal combustion at 600 °C–800 °C. • Only Mo achieved a high leaching rate under acidic and alkaline conditions. The evaluation of the application potential of high-alumina coal fly ash (HACFA) resources relies on the assessment of the phase composition and leaching behavior of valuable elements. Herein, we systematically investigated the particle size, specific surface area, and morphology of high-alumina high-temperature coal ash (HAHCA) produced under laboratory conditions at different temperatures and quantitatively analyzed phase transformations using the Rietveld method. The results revealed that the HAHCA particle size gradually increased, specific surface area gradually decreased, and pores became lesser with the increasing coal combustion temperature of high-alumina coal (HAC) from 400 °C to 1300 °C. Furthermore, HAHCA phases sequentially changed across various temperatures, its main phases at a coal combustion temperature of 400 °C included 29.8 % kaolinite, 6.9 % boehmite, and 5.4 % calcite, but the crystalline phases were the most abundant and turned into 41.2 % mullite, 13.7 % corundum, and 11.6 % plagioclase when the coal combustion temperature reached 1300 °C. Additionally, the leaching behavior of 28 major and trace valuable elements of HAHCA under acidic and alkaline conditions was investigated. Most metal elements easily leached from HAHCA under acidic conditions at coal combustion temperatures of 600 °C–800 °C: the optimal leaching efficiencies of Al, Li, K, Rb, Mg, Ca, Sr, and Ba were 67.64 %, 92.71 %, 76.67 %, 73.46 %, 86.74 %, 98.87 %, 98.42 %, and 61.19 %, respectively. Si, a nonmetallic element, achieved a high leaching efficiency of 48.27 % under alkaline conditions at a coal combustion temperature of 1300 °C. Interestingly, only Mo exhibited a high leaching efficiency of approximately 98 % under acidic and alkaline conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new idea for oil production by co-pyrolysis of oil shale and cherry pit was given. • Adding 30% oil shale into cherry pit rose up the oil yield by14.63% during pyrolysis. • More oxygen migrated into oxygen-containing gases rather than co-oil and char. • More H · free radicals preferring to attack H α and H ar led to a rising co-oil quality. • Synergistic effect occurred during co-pyrolysis due to the hydrogen migration. The pyrolysis oil of oil shale is characterized as being of better quality and having a lower yield, whereas the bio-oil from cherry pit has a higher yield but a higher oxygen content, which limits their efficient and clean application. Thus, the pyrolysates characteristics of oil shale and cherry pit have been investigated using a fixed bed reactor to fully utilize their inherent properties in this paper. In addition, the interaction mechanism during co-pyrolysis is explored by analyzing the hydrogen migration pathways. The results reveal that a remarkable synergistic effect on the oil and gas occurs during co-pyrolysis, and the co-oil yield of OS 30 CP 70 improves by 14.63 % compared with the weighted value. During co-pyrolysis, the concentrations of hydrogen- and oxygen-containing gases are higher than expected, and the hydrogen and oxygen contents of char are lower than expected, which is related to that more hydrogen and oxygen of oil shale and cherry pit migrate into gas instead of char. Additionally, more hydrogen and less oxygen migrate into the co-oil during pyrolysis, causing an increase in aliphatics and a reduction in aromatics and oxygenated compounds, and enhancing the quality of the co-oil. 1H NMR shows that the H · free radical is most likely to attack the H α and H ar sites of cracking fragments rather than H β and H γ sites, resulting in the co-oil containing more short-chain aliphatics and aromatics with fewer rings. Besides, the alkali and alkaline earth metals in cherry pit improve the cracking of hydroxyl and carboxyl groups and inhabit the migration of oxygen into co-oil, leading to a decrease in H o content. The energy efficiency of co-pyrolysis is higher than that of individual pyrolysis, which all exceed 90 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hybrid-CT catalyst shows excellent SCR performance under the poisoning effect of CaO&PbO. • SO 4 2−/ZrO 2 plays dual functions once the Hybrid-CT catalyst is poisoned by CaO&PbO. • SO 4 2−/ZrO 2 could protect the redox and acid centers of catalyst after poisoning by the CaO&PbO. Catalyst deactivation caused by the co-poisoning of alkaline earth metals (CaO) and heavy metals (PbO) is still a problem in the NH 3 selective catalytic reduction (SCR) of NO x in flue gas. In this work, a hybrid catalyst (Hybrid-CT) was being synthesized by grinding CeO 2 /TiO 2 (CT) catalyst and SO 4 2−/ZrO 2 to evaluate the poisoning tolerance. It shown that Hybrid-CT exhibited a higher tolerance against CaO&PbO poisoning compared with CT. Under the co-poisoning of 2.5 wt% CaO and 2.5 wt% PbO, the NO x conversion of Hybrid-CT catalyst could approach to 100 % at 350 °C. Whereas, the NO x conversion of CT was only 66.3 % under the same condition. A series of characterizations suggested that the SO 4 2−/ZrO 2 could inhibit the CaO&PbO poisoning. Once the CaO&PbO present on the surface of Hybrid-CT catalyst, SO 4 2− could convert CaO&PbO into CaSO 4 &PbSO 4 with less toxic, which could protect the redox site and acid site of the CeO 2 /TiO 2. Furthermore, the ZrO 2 released from SO 4 2−/ZrO 2 could serve as a promoter, enhancing the acid performance of CeO 2 /TiO 2 catalysts. Moreover, SO 4 2−/ZrO 2 could also reduce the passive effect of CaO&PbO on nitrate oxide. This work provides a simple and novel way to improve the resistance to CaO&PbO of Ce-based SCR catalysts. [ABSTRACT FROM AUTHOR]

• The acid-alkali leaching method was used for the deashing of Zhundong coal. • The effects of three different deashing schemes were studied. • The removal features of metal elements are related to their existing forms. • Zhundong coal has significant advantages in the preparation of ultra-clean coal. The large-scale application of coal-based deash carbon materials has put forward growing requirements for the removal technology of ash within coal. Extensive research has demonstrated that the contents of ash and metal elements have a large influence on the performance of the coal-based electrodes made from ultra-clean coal. However, there is a lack of research on the ash and mental elemental removal characteristics of Zhundong coal. In the present study, one kind of Zhundong coal characterized by a comparatively low ash content, was utilized to examine the characteristics of ash and metals removal during the acid-alkali ash removal process. An inductively coupled plasma optical emission spectrometer (ICP-OES) was utilized to analyze the metal element concentrations in the solution during ash removal and the metal element contents within the coal samples. The removal characteristics of metal elements were further analyzed based on the detection results. The experimental results indicate significant improvements in the removal of ash and metals through acid-alkali multi-stage leaching. Under the specific experimental condition here, a two-stage acid-alkali ash removal process achieves coal with the lowest ash content of 1.6% and the removal of 98.0% of Fe, 95.2% of K, and 94.6% of Na, with the removal of Al reaching up to 40%. In addition, the Fe removed in the acid leaching step accounted for 95% of the total amount removed, and adding an acid pretreatment step based on acid-alkali leaching can remove 90.2% of Fe within coal. Both the acid leaching and alkali leaching steps exhibit a certain removal proportion for Al, K, and Na elements, which are closely related to the existing form of these elements within the coal. Iron-containing minerals are mostly acid soluble and distributed on the surface of coal particles. Potassium-containing minerals are mainly alkaline soluble, resulting in a removal rate of over 60% in the alkali leaching step of acid-alkali leaching combined with acid pretreatment. The low removal rate of Al (∼40%) is due to the wide variety of Al-containing minerals, such as kaolin, illite, and aluminates, which are less removed during the reaction with alkali due to temperature limitations. The present study can offer improved knowledge on mineral removal to obtain ultra-clean coal for utilization as function materials. [ABSTRACT FROM AUTHOR]

• The effects of AAEMs on the APR of bio-based surrogates over Ni/α-MoO 3 were studied. • AAEMs increased hydrogen yield and promoted TOC removal. • AAEMs prevented Ni leaching and promoted oxygen vacancy formation. • The carbon deposition on the catalyst with Mg was the lowest. Aqueous phase reforming (APR) of biomass derived products is a promising hydrogen generation approach, and many internal alkali and alkaline earth metals (AAEMs) have been proven capable of catalyzing these processes. In this study, APR of various functional groups in biomass derived products over Ni/α-MoO 3 catalyst toward hydrogen production and pollutants control was investigated. The effect of different AAEMs was comprehensively studied under a temperature of 225 °C and a residence time of 30 min. Findings demonstrated that Na, K, Ca, and Mg all showed hydrogen generation and total organic carbon removal capability, whose performances were competitive to Ni/α-MoO 3 catalyst. Moreover, although the presence of single K suppressed the removal of total nitrogen (TN), the combination of K and the Ni/α-MoO 3 catalyst exhibited the optimal removal efficiency of TN (69.92 %). A series of characterization results revealed that the AAEMs effectively prevented Ni leaching in the hydrothermal environment of the Ni/α-MoO 3 catalysts and promoted the formation of oxygen vacancies, inhibiting carbon deposition and deactivation of the catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biomass and coal blends were co-fired to study synergistic SO 2 emission reduction. • Calcium and potassium in the biomass ash absorbed the SO 2 from the flue gas. • Sulfur retained in ash was low for pure coal and biomass and high for middle blends. • FactSage thermodynamic simulation results matched well with the experimental results. • Co-firing biomass with coal can lower the flue gas desulfurization costs. The objective of this study was to understand the synergistic effect of sulfur dioxide (SO 2) emission reduction during the combustion of biomass-coal blends in comparison to pure coal by recording the gaseous SO 2 concentrations, analyzing the composition of combustion ash by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), and simulating and verifying the fate of sulfur by a thermodynamic equilibrium software (FactSage). In Set A experiments, five combinations of coal and steam-exploded biomass (100/0, 75/25, 50/50, 25/75, 0/100 in percentages by mass) were co-fired in a 1.5 MW th pilot-scale combustor. In Set B, pure coal (100/0) and an 85/15 percent mass blend of coal and torrefied biomass were co-fired in a 471 MW e utility boiler. Woody biomass contains lower amounts of sulfur compared to coal and the linear lowering of SO 2 emissions as a result of co-firing is called the dilution effect. For Set A tests, FactSage predicted, and ash analysis confirmed that calcium was primarily responsible for the synergistic emission reduction (beyond dilution effect) in all the blends, except in pure biomass, where potassium was responsible. During pure coal combustion, 41.1% of the sulfur in the system was absorbed in the ash, compared to 97.0% during pure biomass testing. In Set B tests, the 85/15 coal-biomass blend, showed a 28.1% reduction in SO 2 emissions along with a 22.1% reduction in the lime slurry utilization at flue gas desulfurization (FGD) towers compared to pure coal, which is equivalent to saving 7.4 L of lime slurry per MW e -hour. The results suggest that blending woody biomass with coal can help coal-fired utility boilers meet environmental emission standards and reduce desulfurization costs. These results are important since the current literature is deficient in research conducted at suspension-fired full-scale boilers to reduce SO 2 emissions by co-firing coal and biomass blends. [ABSTRACT FROM AUTHOR]

• Large particle size biomass is conducted for oxygen-stream gasification. • The spatial distribution of AAEMs are detected and analyzed. • X-ray CT technology is employed to interpret AAEMs catalytic gasification. • The mechanism of AAEMs catalytic gasification for large particle biomass is studied. To evaluate the effect of alkali and alkaline earth metals (AAEMs) species on the catalytic gasification of large particle-size biomass, a vertical fixed-bed reactor is conducted for candlenut wood gasification under the oxygen-stream atmosphere. The biochar samples derived from gasification are characterized by SEM, X-ray CT, BET, and FTIR. Tar and syngas are analyzed via GC–MS and GC respectively. Advanced X-ray CT technology provides beneficial visualization to assist in the interpretation of the catalytic gasification of large particle-size biomass loaded with AAEMs. The results indicate that a progressive augmentation of AAEMs content along the radial direction and end surface for all loaded samples and biochar samples, which could also be visualized from the 3D reconstruction of X-ray CT. Many large pores (40–60 μm) aligned along the grain direction collapse after the gasification and generate numerous micropores in biochar samples. 10–20 μm pores are more prominent in biochar as the biomass samples are loaded with KCl and CaCl 2. The biochar from gasification of biomass loaded with CaCl 2 has more well-developed pores, a larger specific surface area, and –OH compounds, aldehydes, ketones and carboxylic acids. The addition of AAEMs facilitates the high generation of M1 compounds (contains 1 benzene ring) in the tar and suppresses the enhancement of M4 compounds, long-chain alkanes, and other compounds. The lowest carbon conversion (57.12 %) is acquired from acid-washed sample. H 2 concentration augments but CO concentration declines by loading AAEMs. The highest H 2 concentration of 62.1 % is detected by the addition of CaCl 2. When loaded with KCl, the syngas calorific value reduces by 1.37 %, whereas loaded with NaCl, CaCl 2 , and MgCl 2 show an augmentation of 11.48 %, 10.56 %, and 2.55 %, respectively. A decrement of C n H x concentration in the syngas derived from gasification of biomass samples loaded with KCl and MgCl 2 and an increment one loaded with NaCl and CaCl 2 are acquired. [ABSTRACT FROM AUTHOR]

• Nb/MnO 2 -S with the low-temperature activity and calcium-resistant property was prepared for NH 3 -SCR. • Sulfates species protect Nb active sites by combining with calcium on Ca–Nb/MnO 2 -S. • The redox property and acidic sites are reserved on calcium-poisoned Nb/MnO 2 -S. • Calcium-poisoned Nb/MnO 2 -S exhibits the superior activity owing to the efficient NH 3 adsorption. Reducing the poisoning effect of alkaline earth metals over catalysts in industrial fields presents a great challenge to selective catalytic reduction (SCR) of NO x with ammonia. Herein, we successfully introduce sulfates to the surface of supported manganese-based oxides (Nb/MnO 2 -S) for trapping calcium species, and Nb/MnO 2 -S catalyst with superior low-temperature performance and calcium-resistant property still exhibits excellent de-NO x activity in a wide operating temperature window (175–350 °C, over 80 % NO x conversion with a gas hourly space velocity of 60,000 h−1) after calcium poisoning. In this case, the addition of sulfates increased the quantity of chemisorbed oxygen on Nb/MnO 2 -S, thus accelerating the redox cycle in NH 3 -SCR reaction. Significantly, compared with calcium-poisoned Nb/MnO 2 , relevant spectroscopy analysis and theoretical calculations further reveal that sulfates species prefer to interact with calcium and release the Nb active sites, which maintains the efficient NH 3 adsorption and preserves a large amount of Brønsted acid sites over calcium-poisoned Nb/MnO 2 -S, thus promoting calcium-resistant performance. This work will provide a general strategy to develop calcium-resistant SCR catalysts with low-temperature activity for industrial applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electron-giving interaction of Ca, Sr, and Ba inhibited H species adsorption while enhancing CO dissociative adsorption, contributing to the formation of χ-Fe 5 C 2. • Mg decreased CO dissociative adsorption while enhancing H species adsorption. • This synergistic effect of Sr and Na resulted in the strongest CO dissociative adsorption capacity and the highest total amount of active iron carbide. • The light olefins yield of FeMnSrNa catalyst (427.0 g/(h·kg Cat)) was significantly higher than that of FeMnSr catalyst (341.4 g/(h·kg Cat)) and FeMnNa catalyst (80.6 g/(h·kg Cat)). For the high-temperature Fischer-Tropsch synthesis (HTFT) of light olefins (C 2 =-C 4 =), alkaline-earth metals (Mg, Ca, Sr, and Ba) modified FeMn catalysts were prepared using precipitation and impregnation methods. It was demonstrated that the electron-giving interaction of Ca, Sr, and Ba decreased the adsorption of H species while improving the dissociative adsorption of CO. This interaction resulted in the production of χ-Fe 5 C 2 , which increased CO conversion and C 2 =-C 4 = selectivity. Compared with Ca and Ba, the FeMnSr catalyst had the strongest CO dissociative adsorption capacity and the highest χ-Fe 5 C 2 content with the best FTS performance. When Sr and Na were introduced simultaneously, the synergistic effect of Sr and Na inhibited the formation of θ -Fe 3 C and the aggregation of catalyst particles, and also increased the χ-Fe 5 C 2 content. This synergistic effect resulted in the highest surface basicity of FeMnSrNa catalyst, the highest electron cloud density on the surface of Fe atoms, the weakest H species adsorption, the strongest CO dissociative adsorption, and the highest total amount of active iron carbide, which improved the FTS performance. The light olefins yield of FeMnSrNa catalyst (427.0 g/(h·kg Cat)) was significantly higher than that of FeMnSr catalyst (341.4 g/(h·kg Cat)) and FeMnNa catalyst (80.6 g/(h·kg Cat)). [ABSTRACT FROM AUTHOR]

• Catalytic effects of Na/K/Ca on G-type lignin steam gasification were explored. • Gaseous hydroxides are key to the excellent catalytic effects of Na 2 CO 3 /K 2 CO 3. • High-melting CaO results in poor catalytic performance of CaCO 3. • 5 mmol Na+ loading showed the best catalytic effect on lignin steam gasification. • Na 2 CO 3 outperformed Na 2 SO 4 , NaHCO 3 , and NaAlO 2 in catalytic effectiveness. This work studies the effects of alkali and alkaline earth metallic species (AAEMs) (Na 2 CO 3 , K 2 CO 3 , and CaCO 3), Na+ impregnation amount (2, 5, and 7 mmol) and sodium salts (NaHCO 3 , Na 2 SO 4 , and NaAlO 2) on the gasification characteristics and product distribution of G-type lignin in a fixed-bed system for continuous gasification. The results showed that six catalysts all could improve lignin gasification performance by increasing total gas yields, syngas yields, H 2 /CO ratios, and carbon conversion rates. Na 2 CO 3 had the strongest catalytic ability, followed by NaHCO 3 and K 2 CO 3 , while CaCO 3 , Na 2 SO 4 and NaAlO 2 had poor catalytic abilities. Gaseous AAEMs, especially NaOH and KOH, could enhance tar cracking, volatiles reforming, coke gasification, the water-gas shift reaction, and methane steam reforming. The high melting points of CaO and NaAlO 2 greatly reduced the catalytic capacities of CaCO 3 and NaAlO 2. AAEMs could combine with the carbon matrices to form carboxylate structures or phenol/aldehyde structures which might volatilize to catalyze homogeneous reactions. Moderately increasing Na+ impregnation amount to 5 mmol was beneficial to lignin gasification, but excessive impregnation reduced the gasification parameters. In addition, all six catalysts had effects on the tar composition, especially K 2 CO 3 and NaAlO 2 , which could effectively catalyze tar cracking and reduce heavy compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanochemical hydrogenation of shell wastes was studied at room temperature. • Alkaline metals can selectively assist the hydrogenation of shell wastes to CH 4. • The calcium metal has a better effect and the methane yield can reach 45.04%. • By doping Ru the methane yield of shell wastes can be improved to 54.76%. • This study provides a method to eliminate shell wastes and produce CH 4 fuel. Producing clean fuel using shell wastes (eggshell and clamshell) can eliminate food waste and alleviate the energy shortage. Mechanochemical hydrogenation of eggshell/clamshell was investigated at room temperature. The results show that the alkaline earth metals can effectively assist the hydrogenation of shell wastes to CH 4. The calcium metal has a better effect, and the methane yield for the calcium-assisted hydrogenation of clamshell and eggshell reaches 45.04% and 33.30% with 100% CH 4 selectivity. At the same time, the calcium-assisted methanation of shell wastes in the presence of transition metals (Fe, Co, Ni, Ru) was investigated. By doping Ru, the methane yield of clamshell and eggshell was improved to 52.62% and 54.76%, respectively. The milling time, rotating speed, hydrogen pressure, and the species of the doped transition metals influence the calcium-assisted methanation of shell wastes. This study provides an alternative method to eliminate shell wastes and produce clean CH 4 fuel at room temperature. [ABSTRACT FROM AUTHOR]

• The combined effect of the coexistence of carrier, catalyst and storage site on NO x adsorption was investigated. • The experimentally observed "fast" sites of NO x storage are reproduced by the model of the proximity of Pt-Ba clusters. • The interesting trend of NO x adsorption energy with different adsorption sites were systematically outlined. • Two interaction models, s NOx -p Ba and p NOx -d Pt , are proposed to explain the NO x activation mechanism. The advancement of low to zero carbon fuels for internal combustion engines has made Nitrogen oxides (NO x) emissions a focal point of engine aftertreatment. Lean NO x Trap (LNT) is one of the most promising technologies for reducing NO x emissions in light-duty vehicles. The proximity of barium (Ba) to platinum (Pt) sites plays a significant role in the adsorption, reduction, and desorption of NO x inside LNT. A simultaneous loading of Pt clusters (Pt 3) and barium oxide clusters ((BaO) 2) on γ-Al 2 O 3 (1 0 0) was innovatively established in this study, and the effect of oxide carrier - triatomic catalyst clusters - bimolecular alkaline earth metal oxide clusters was considered comprehensively to examine the effect of Pt-Ba proximity on the NO x adsorption behavior. Interesting trends in the adsorption energy and activation of NO x molecules (including NO/NO 2 and the strong greenhouse gas N 2 O) due to differences in the adsorption sites (from Pt sites to Pt-Ba proximity sites and finally to Ba sites) were found, and the essential reasons for such variations were elucidated by an exhaustive electronic structure analysis. The results of this study are an interesting complement to the current mechanism for storage and reduction of NO x. [ABSTRACT FROM AUTHOR]

• The PM forming mechanism during high-alkali char gasification was clarified. • The size of PM decreased with pressure increasing and temperature decreasing. • Over 90% of PM obtained at 3 MPa has a particle size of 0.2–1.5 μm. • Diatomite exhibited good performance on restraining PM release than kaolin. • CaO competed to react with Si- and Al-bearing minerals and promoted PM release. In this study, the release and formation characteristics of ultrafine particle matters (PM) during the gasification of Na-rich char are investigated. Two different pre-treatment methods, i.e., water washing and mineral loading, were employed to figure out the effects of various minerals on the deconvolution behaviors of PM, enabling the development of countermeasures. Furthermore, the mineralogical characteristics of the ash resulting from the mineral loading were also discussed. Results showed that a large amount of fine NaCl particles was generated during Na-rich char gasification. Gasification temperature and pressure essentially govern the concentration of Na and Cl species in the gas phase, which determines the quantity and morphology of PM. Specifically, the particle size of PM obtained at 1000 and 1050 °C is mainly distributed in the range of 0.2–0.4 μm. For the W-char gasified at 1100 and 1150 °C, the PM with the size between 0.6 and 1.2 μm is predominant. On the other hand, the particle size of PM decreased remarkably as the gasification pressure increased from 0.1 to 3 MPa. Additionally, due to the low carbon conversion rate of W-char during the CO 2 gasification at 1100 °C, over 75% of the total PM were in the size range of 0.2–0.6 μm. The gasification of kaolin loaded W-char generated abundant spherical particles mainly present as alkali and alkaline earth metal aluminosilicates rather than NaCl particles. When it comes to adding diatomite into char, only a few spherical particles, mainly present as aluminosilicates, were detected, indicating the superior performance of diatomite on restraining PM release. The addition of diatomite into W-char could reduce ash fusion temperature, and the agglomerated coarse particles in bottom ash could capture the PM, which inhibited the release of PM to some extent. In contrast, the CaO added in char reacted with the clay and quartz that would otherwise immobilize Na, leading to the more intense release of Na- and Ca-bearing PM. [ABSTRACT FROM AUTHOR]

• Three types of solution with different severities were used to wash rice straw. • One sharp peak was in DTG curves for Raw-RS, but two peaks for HCl-RS and APBO-RS. • Evolution of evolved gases (H 2 O, CH 4 , CO, CO 2 , and C O stretching) was analyzed. • APBO pretreatment showed the highest activation energy for rice straw pyrolysis. • The relative content of levoglucosan was increased because of the removing of AAEMs. Washing pretreatment is a promising method for upgrading biomass by removing alkali metal and alkaline earth metals (AAEMs). In this study, three types of solution with different pretreatment severities (i.e., water (H 2 O), dilute hydrochloric acid (HCl) solution, and aqueous phase bio-oil (APBO)) were used to study the effects of the washing pretreatment on the pyrolysis behaviors and kinetics of rice straw. The pyrolysis experiments of raw and pretreated rice straw (Raw-RS, H 2 O-RS, HCl-RS, and APBO-RS) were carried out using TG-FTIR and Py-GC/MS. Results show that among the three types of washing pretreatment methods, the APBO washing pretreatment has the highest removal efficiency of AAEMs: 99.7% of K, 91.7% of Na, 96.6% of Mg, and 95.2% of Ca. According to TG-FTIR results, only one sharp mass loss peak was present in the DTG curves of Raw-RS and H 2 O-RS, whereas two mass loss peaks (one sharp peak and one shoulder peak) were observed in HCl-RS and APBO-RS. The evolution pattern of the volatile compounds (H 2 O, CH 4 , CO, CO 2 , and C O stretching) was thoroughly investigated, and the absorbance intensity of these components increased with the washing pretreatment of APBO and HCl. The APBO washing pretreatment had the highest activation energy in the conversion rate of 0.2–0.75, followed by HCl and H 2 O washing pretreatment. According to the Py-GC/MS results, the washing pretreatment reduced the relative contents of acids, ketones, furans, and phenols in bio-oil, whereas removing of AAEMs increased the relative contents of anhydrosugars (mainly levoglucosan). Among the three types of washing pretreatments, the APBO washing pretreatment had the most remarkable influence on the property of bio-oil, and this indicates that the APBO washing pretreatment is a promising method for upgrading biomass and its pyrolytic product. [ABSTRACT FROM AUTHOR]

[Display omitted] • CO 2 -enhanced water leaching can remove alkali/alkaline earth metals in biochar. • CO 2 -enhanced water leaching is facile without clearly destroying biochar structure. • Pore structure of biochar plays a dominant role in enriching phenols in bio-oil. • Alkali/alkaline earth metals enhance the O -compounds decarbonylation in bio-oil. Catalytic conversion of volatiles from biomass pyrolysis over biochar and its mechanism are important to the efficient utilization. The properties of biochar including alkali/alkaline earth metallic species (AAEMs) and pore structure exert the influence on bio-oil quality. In this work, a facile demineralization method by CO 2 -enhanced water leaching (CEWL) of biochar from bagasse pyrolysis was first applied to catalytic upgrading of pyrolysis bio-oil. The effect of AAEMs content and pore structures in biochar catalysts on upgrading performances was investigated. The results show that the CEWL of biochar can effectively remove most inherent AAEMs without obviously destroying pore structures. Pore structure of catalysts plays a dominant role in increasing phenols contents to 47.7% over CO 2 -activated biochar from 25.8% without biochar. The reaction mechanism was proposed that AAEMs enhanced the polymerization of aromatic hydrocarbons and the decarbonylation of the oxygenated compounds. High temperature is profitable to the generation of phenols and polycyclic aromatic hydrocarbons owing to easier decarbonylation of ketones and demethylation or demethoxylation of phenols. [ABSTRACT FROM AUTHOR]

[Display omitted] • A-site substituted perovskite used for photothermal catalytic reforming of toluene. • Alkaline earth metal substitution adjusted the oxygen species content on catalyst. • Active oxygen species affected the morphology and quantity of coke. • The photoactivation of oxygen species by UV–vis was proposed. Photothermal steam reforming (PTR) has emerged as an attractive approach for catalytic tar removal, due to the excitation of the photothermal synergistic effect. However, the role of oxygen species in PTR is still unclear. In this paper, the effect of alkaline earth metals (Ca and Sr) A-site-substitution on perovskite LaNi 0.6 Mn 0.5 O 3 was investigated to reveal the role of oxygen species in PTR. The substitution of alkaline earth metals into perovskite lattice affected the dispersion of nickel and significantly adjusted the active oxygen species content on the catalyst surface. Oxygen species are crucial to the carbon deposition behavior of catalysts in PTR. La 0.7 Ca 0.3 Ni 0.6 Mn 0.5 O 3 was rich in reactive oxygen species, which effectively inhibited the deposition and graphitization of coke, resulting in its good coke resistance and catalytic stability in PTR. Ultraviolet–visible light (UV–vis) supported the formation of oxygen vacancies and the dissociation of H 2 O to hydroxyl radicals through the photochemical reaction, which ultimately increased the surface adsorbed oxygen contents. Meanwhile, UV–vis promoted the migration and reaction of lattice oxygen. The photoactivation of oxygen species by UV–vis effectively enriched active oxygen species and improved the coke resistance, which resulted in enhanced catalytic stability of PTR at low-temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fast CO 2 capture and simultaneous utilization via mineralization to CaCO 3. • One-step capture and utilization of CO 2 at ambient conditions. • Use of a combination of organic and inorganic CO 2 absorption promotors. • Macromolecule-mediated crystallization produces CaCO 3 with different properties. CO 2 mineralization which involves the reaction of CO 2 with alkaline earth metal cations to form carbonates, is a promising pathway that could be crucial for combating global warming via long-term CO 2 utilization and storage. However, due to the large abundance of natural calcium carbonate (CaCO 3) and advanced milling techniques, micron-ranged CaCO 3 is conventionally produced via the top-down method because it is more economically attractive than mineralization or precipitation unless particles with functional properties are generated so that a higher product value is achieved. In this study, inspired by the natural formation of nacre, which is produced naturally via controlled crystallization (using environmental CO 2) in the marine environment, we produce CaCO 3 particles with different morphologies via single-step CO 2 capture and mineralization. We used a gas diffuser reaction setup to bubble CO 2 in liquid media containing CO 2 absorption promotor, water-soluble polymer, and surfactant as crystal growth modifiers, and Ca2+ to form functional CaCO 3. First, different inorganic and organic CO 2 absorption promoters and their combinations were investigated for their effectiveness on Ca2+ conversion to CaCO 3. Ca2+ conversion and pH of the reaction system with various concentrations of CO 2 absorption promoters were monitored every 5 min. Second, the effect of the polymer combined with different concentrations of surfactant on CaCO 3 properties was studied. It was found that the combination of triethanolamine and ammonium hydroxide as absorption promotors results in 53.2% Ca2+ conversion into stable CaCO 3 particles within 5 min of CO 2 bubbling. Absorption promotors themselves could not regulate the particle shape; however, with increasing concentrations, smaller particles agglomerated to form bigger rhombohedral particles. Polymer and surfactant-mediated mineralization of CO 2 produces spherical and hollow, stable calcite particles that could serve as dies, heavy metal adsorbents, supports to catalysts, functional composite fillers, etc. [ABSTRACT FROM AUTHOR]

Heterogeneous copper/alumina catalysts with MgO, CaO, SrO, and BaO were prepared by co-precipitation synthesis method and characterized by means of N 2 -sorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and subsequent H 2 temperature-programmed reduction (H 2 TPR) and H 2 /CO 2 temperature-programmed desorption (H 2 and CO 2 TPD). The incorporation of oxides increases the metallic Cu surface area, as follows: Mg > Sr > Zn > Ca > Ba. These metal oxides thus increased the interaction between CuO and Al, resulting weaker reducibility of CuO. MgO increased the number of carbon dioxide and hydrogen adsorption active sites, whereas Ba augmented the basicity of the material. The activity with respect to methanol production matched the increase of Cu surface. As CH 3 OH selectivity monotonically decreased with the temperature, CO increased proportionally. Among the examined catalytic materials, Cu/MgO/Al 2 O 3 exhibited a higher reactant conversion than the pelletized commercial analogues. Hydrogenation performance of the catalysts thus depended on both, the Cu surface site availability and the interaction between copper–metal oxides. While the industrial Cu/ZnO/Al 2 O 3 has been extensively employed for quite some time, it is demonstrated herein that even upon the application of inexpensive non-critical raw material resources, such as MgO, an increment in bifunctional catalysis performance is attained. The Cu/Mg/Al catalyst showed a turnover frequency of 11.9 × 10 −4  s −1 , which is higher than the commercial HFR120 and LURGI catalysts. [ABSTRACT FROM AUTHOR]

Zhundong coal, rich in the Alkali and Alkaline Earth Metal elements, causes severe ash deposition during the combustion in many power plants. In this paper, the influence of vermiculite, as an additive, on ash deposition formation and the corrosion phenomenon caused by ash deposition are investigated in a drop tube furnace system. The formation process of ash deposition under real working condition can be simulated in this furnace system. The results show that vermiculite has a significant inhibition effect on the formation and growing process of ash deposition, as well as the corrosion phenomenon. At the beginning of ash deposition, the swelling vermiculite can effectively absorb the SO 2 in the flue gas, which restrains the formation of Na 2 SO 4 in the inner ash, close to the surface of heat exchangers. The mineral in internal inner ash gets changed and the phenomenon of corrosion on the heat exchangers surface gets alleviated. Meanwhile, the external inner ash presents with loose structure instead of the molten condition, which lowers possibility for ash deposition to grow. In outer ash deposition, close to the flue gas, the content of layered particles with high melting point, as Mg 2 SiO 4 , increases and viscous particles, like Ca 2 Al 2 SiO 7 , are separated from each other by the force of the vermiculite swelling. As a result, adding vermiculite makes it hard for ash deposition to form and grow. According to the experiments, with more than 5% blending ratio of vermiculite, the vermiculite additive has a positive effect on restricting the ash deposition. [ABSTRACT FROM AUTHOR]

• Synergistic effects of Fe 2 O 3 -CaO-MgO ternary flux system were revealed. • Flow temperature and T CV varied in V-shape as Fe 2 O 3 /(CaO + MgO) ratio decreased. • The formation and eutectic of ferroan spinel led to low flow temperature. • The presence of Fe and a CaO/MgO ratio of 4:6 could limit slag crystallization. • Adjusting the Fe 2 O 3 /(CaO + MgO) ratio to 1 is beneficial for gasifier slagging. Basic oxides are usually widespread in low-rank coals and cause many ash-related problems in gasification applications. In this paper, the synergistic effects of the ternary flux system of Fe 2 O 3 -CaO-MgO in lowering the ash fusion temperature and improving the viscosity-temperature characteristics were verified by testing the properties of samples with different Fe 2 O 3 /(CaO + MgO) ratios. The flow temperatures and temperatures of the critical viscosity decreased and then increased with the decrease of Fe 2 O 3 /(CaO + MgO) ratio and reached the lowest point when the iron oxide and alkaline earth metal oxide (CaO, MgO) contents were close to each other. From the perspective of mineral transformation, the formation of low melting point ferroan spinel and the eutectic between anorthite and ferroan spinel are the main mechanisms of synergism. No severe crystallization was observed in the iron-rich slags because Fe2+ could reduce the crystallization tendency. As CaO and MgO dominated the basic oxides, a CaO/MgO ratio of 4:6 effectively limited the crystallization and lower the temperature of critical viscosity (T CV). Thus, when regulating the coal ash fluidity, the content of iron oxide and the ratio between CaO and MgO should be consciously balanced to meet the requirements of the gasifier for slag removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Residue fluid catalytic cracking (RFCC) processes heavy and contaminated feedstocks. • Mechanism of catalyst contamination and passivation have been discussed. • Nickel and vanadium are the most harmful contaminants of RFCC catalyst. • Antimony, bismuth and boron have been identified as nickel passivators. • Tin, alkaline earth and rare earth compounds are the major vanadium passivators. The catalysts used for residue fluid catalytic cracking must have good catalyst activity, selectivity, hydrothermal stability, coke selectivity and metals tolerance to high concentrations of heteroatoms such as N, S, Fe, Na, Ni, and V. Recent increase in energy demand leads to the processing of heavy feedstocks such as atmospheric residue that hitherto have been disfavoured. Processing these feedstocks comes with several challenges due to the presence of these heteroatom poisons that are detrimental to catalysts as they either permanently or temporarily deactivate or poison the catalysts, thereby promoting undesirable reactions such as dehydrogenation and coke production. To give perspective on these challenges, RFCC technologies, catalysts, and catalyst deactivation are discussed. The differences and limitations of conventional fluid catalytic cracking and contemporary residue fluid catalytic cracking are also highlighted. This study emphasises the passivation of Ni using antimony, rare earth metals, bismuth and boron compounds and passivation of V using tin, rare earth metals, and basic alkaline earth compounds such as Mg. The work also presents new illustrations of nickel and vanadium poisoning mechanisms. While antimony successfully mitigates nickel's deleterious effects; it leads to NOx emissions and increased bottom fouling. Boron does not exhibit such a problem and has been shown to be a good substitute for antimony in mitigating the harmful effect of nickel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Devolatilization at 350–550 °C significantly increased the K content in corn stalks. • K has a more significant catalytic effect on later gasification stage. • The fitting accuracy of random pore model decreases with the increase of K content. • K content, conversion rate and activity parameter were correlated in improved model. • Accurate prediction for gasification of high inorganic content biomass was realized. In this study, to investigate the effect of medium temperature devolatilization (MTD) on biomass gasification kinetics and build an improved kinetic model that can accurately describe the gasification of MTD-char, the isothermal steam gasification experiments were performed by using a thermogravimetric analyzer on corn stalk and its MTD-chars obtained at 200–550 °C. The results demonstrate that the wide divergence in the influences of alkali and alkaline earth metal (AAEM) on the gasification under different conversion rates (x) led to the fitting error of the random pore model for corn stalk gasification process, and this fitting error was more significate in the MTD-char with higher AAEMs content. Accordingly, a semi-empirical kinetic model, namely RPM+, which is suitable for biomass gasification with high AAEMs content, especially the MTD-char, was developed, the catalytic effects of AAEMs on biomass gasification were accurately described by the mutual coupling of AAEMs content, x and an activity parameter (k a) in RPM+. This study is of great significance to the process simulation and equipment design of biomass staged gasification. The results provide the theoretical foundation for realizing the high-value utilization of biomass with high AAEMs content through gasification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ash fusion temperature reached the minimum as coal addition was 40 wt%. • Slagging propensity was mitigated proved by the ash fusibility index. • In-situ morphological analysis revealed the fusion mechanism. • Coal ash retarded the release of potassium by the formation of aluminosilicates. • The priority areas were in anorthite, melilite and leucite zones for co-gasification. Biomass gasification is a promising technology to realize low carbon emission and clean energy generation processes, while the ash-related problem is the main limitation of its large-scale application. The coal additives can effectively alleviate ash sintering and melting issues. The in-situ ash fusion behavior, mineral transformation, and potassium retention process were explored in the co-gasification condition of soybean straw and coal. The formation of alkali and alkaline earth metal (AAEMs) based minerals led to the low ash slagging propensity with the coal additives due to the reaction between SiO 2 , Al 2 O 3 and AAEMs. Then the in-situ observation indicated that the formation of refractory minerals promoted the reduction of shrinkage and the increase of AFTs. In this sense, the mineral evolution at different quenching temperatures further revealed that the alkaline earth metals were prone to react with SiO 2 or Al 2 O 3. Moreover, the decreasing amount of gaseous potassium meant that the K could be effectively retained by coal additives. Based on this in-situ analysis, the combinative thermodynamic calculation suggested that the priority areas were in the anorthite, melilite and leucite primary phase zones to ensure the smooth operation of the co-gasification process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acid treatment removed intrinsic minerals of biochar optimized the pore structure. • New –OH produced has lower potential energy to reduce Cr(VI) and combine with Cr(III). • The promotion of Cr(VI) adsorption by the four elements is Fe3+> Mg2+＞ Ca2+> K+. • The adsorption of AAEMs and transition metals to Cr(VI) are ion exchange, precipitation and complexation. Cr(VI) is extremely harmful to the ecological environment. The secondary purification method of treating low concentrations is not satisfactory currently. In this paper, wheat straw were pyrolyzed at 800 °C to obtain biochar, which were used to explore the effect of minerals on adsorption effect as a precursor at different pH and 25 °C. The biochar was gradually eluted with HCl and HF to remove the ash, soon loaded with K+, Ca2+, Mg2+ and Fe3+, respectively. The results show that under the action of H+, the C O bonds left after mineral removal have lower potential energy than the original surface functional groups in terms of conversion to –OH and binding to Cr. The order of promotion of Cr(VI) adsorption by the four elements is Fe3+> Mg2+＞ Ca2+> K+. As the radius of metal ions decreases, so does the electronegativity of biochar and the surfactive site increases. The adsorption mechanisms of alkali metals, alkaline earth metals and transition metals to Cr(VI) are mainly based on ion exchange, precipitation and complexation, respectively. The adsorption of Cr(VI) by wheat straw biochar was consistent with the quasi-secondary kinetic model. Combined with the results of intraparticle diffusion model fitting, it shows that this process is a multi-stage adsorption process with the combined effect of physical and chemical adsorption. [ABSTRACT FROM AUTHOR]

• Effect of acid-washing pretreatment on the volatile-char interactions was studied. • AAEMs catalyzed both primary pyrolysis and secondary volatile-char interactions. • AAEMs removal and weakened interactions promoted sugar-enriched bio-oil production. • AAEMs removal and weakened interactions reduced char yield with more pores formed. • 63.37% bio-oil was obtained for packed bed by weakened interactions & AAEMs removal. The purpose of this study is to investigate the effect of acid-washing pretreatment on the poplar wood (PW) pyrolysis under different volatile-char interactions, the experiment was conducted in a self-designed fixed-bed pyrolysis reactor. It was found that acid-washing pretreatment could alter the surface morphology of PW, increase the cellulose crystallinity and reduce the inorganic ash components (mainly Alkali and Alkaline Earth Metal species, AAEMs). AAEMs acted as catalysts for sugar ring fragmentation and charring reactions during both primary pyrolysis of biomass and secondary volatile-char interactions. The removal of AAEMs would increase the bio-oil yield and decrease the biochar and non-condensable gas yields, same trend was also observed with the decreasing volatile-char interactions. The removal of AAEMs and weakened volatile-char interactions both resulted in an increase of C content and a decrease of O content of biochar with more pore structures generated, especially micropores, the content of anhydrosugars in bio-oil was also largely enhanced. In addition, the decrease of volatile-char interactions would significantly reduce the effect of AAEMs in biomass on the pyrolysis process. A highest bio-oil yield of 63.37 wt% with 34.38% of anhydrosugars could be obtained even for a packed fixed-bed reactor by intentionally reducing volatile-char interactions and removing AAEMs from biomass during the process. [ABSTRACT FROM AUTHOR]

• Co-pyrolysis of oil shale with nutshell biomass (peanut shell). • A thermogravimetric analyzer and a fixed-bed reactor are combined for research. • Co-pyrolysis interaction mechanism between oil shale and peanut shell. Aiming at the low oil yield of oil shale, and the high content of oxygen in biomass pyrolysis oil, the co-pyrolysis of oil shale and peanut shell were studied by thermogravimetric analyzer and fixed bed reactor. Based on the co-pyrolysis characteristics, kinetic and oil phase products analysis, a series of co-pyrolysis interaction mechanism has been proposed. The co-pyrolysis caused the earlier decomposition of oil shale and higher conversion rate of blended feedstock. The contribution of co-pyrolysis to the total conversion and oil phase products yield was most significant with biomass blending ratio of 50 %, while the contribution to the activation energy and the generation of aliphatic hydrocarbons was most significant when the ratio was 25 %. The co-pyrolysis interaction at low-temperature (160–400 °C) is dominated by oil shale radicals promoting biomass bond breaking and the minerals catalysis on biomass decomposition. For high-temperature (400–600 °C), it is dominated by biomass alkali/alkaline earth metals which catalyze oil shale decomposition. The interaction promotes the formation of aliphatic and aromatic hydrocarbons in the oil, reduces the average carbon chain length and increases the light oil content. [ABSTRACT FROM AUTHOR]

• The effects of AAEMs on the release stages of HCN, NH 3 and HNCO were explained. • NaCl reduced the total yield of nitrogen-containing gases by 17.79%. • The reaction paths of nitrogen-containing gases were simulated by DFT. • Inhibition effect on nitrogen-containing gases: NaCl > KCl > CaO > MgCl 2. Effects of alkali metals (KCl, NaCl) and alkaline earth metals (CaO, MgCl 2) on the evolution of nitrogen-containing compounds and product distribution during pyrolysis of phenylalanine were studied in this study. TG-IR was used to monitor the change of nitrogen-containing gases (NH 3 , HCN, HNCO) with temperature and their final releasing amounts. Using M06-2X method and 6-31g(d) basis group, the pyrolysis reaction paths of phenylalanine were simulated, and the influence mechanism of AAEMs on the evolution process of nitrogen-containing compounds was explored from the molecular level. The results show that KCl promoted the release of HCN and HNCO and inhibited the release of NH 3 ; however, NaCl inhibited the production of NH 3 and HCN, promoting the production of HNCO. Both CaO and MgCl 2 promoted the release of HCN and NH 3 and inhibited the release of HNCO, while MgCl 2 had a minor effect on HNCO. Theoretical simulations reveal that the main reason for affecting the total amount of three nitrogen-containing gases is the competitive effect of AAEMs on the formation paths of aromatic nitrogen compounds. KCl and CaO inhibited the formation paths of aromatic nitrogen compounds, while NaCl and MgCl 2 function conversely. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-firing the biomass with high-Ca coal reduces the ash slagging rates by 17–65%. • Co-firing corn stalk with the high-Si/Al coal exacerbates the ash slagging tendency. • Torrefaction aggravates the growth of slagging during combustion except for that of sawdust. • Additional measures are suggested to alleviate the ash slagging of torrefied herbaceous biomass. Torrefaction is a competitive technology for biomass upgrading. Knowing that the effects of torrefaction on ash-related issues during biomass combustion and co-combustion with coal have been less investigated, Parts Ⅰ and Ⅱ of this work investigated the particulate matter emission and ash fouling behavior. To be a continuation, in the present paper, the effect of biomass torrefaction on ash slagging deposition which occurs in the high-temperature areas of the furnace was focused on. Two herbaceous biomass, one woody biomass, and their torrefied chars were fired and co-fired with two coals respectively on a drop-tube furnace at 1300℃. The slags were collected from mullite tubes placed in the furnace for quantification and characterization. Computer-controlled scanning electron microscope (CCSEM) was employed to obtain the distribution of particle size and inorganic species in the bulk ash. The results indicate that co-firing the biomass with high-Ca coal significantly reduces the ash slagging rates due to the substitution of alkalis by Ca from the silicates/aluminosilicates which inhibits the agglomeration and sintering of the ash particles, and finally reduces the inertial impaction and capture of the particles on the tube. Co-firing corn stalk with the high-Si/Al coal promotes the formation of alkaline aluminosilicates which are sticky at a high temperature. Therefore, the slagging tendency is exacerbated. Torrefaction reduces the ash slagging rate of sawdust resulting from the effective removal of S and Cl and the transformation of AAEMs (alkaline and alkaline earth metals) into less-reactive forms during torrefaction which reduces the vaporization and transformation of AAEMs into coarse particles as aluminosilicates by surface reactions. However, the ash slagging rates are increased by torrefaction for other fuels due to more retention of AAEMs after torrefaction resulting in more mixed silicates or aluminosilicates in bulk ash contributing to the growth of slagging deposits during combustion. Measures are suggested to be taken, such as optimizing the operation conditions, co-firing with high-Ca coals, using additives, etc. to alleviate the ash slagging during torrefied herbaceous biomass combustion. [ABSTRACT FROM AUTHOR]

To understand the detailed catalytic mechanism of ion-exchanging AAEM species on biochar structure and its specific reactivity during CO 2 /H 2 O gasification, the experiments were carried out in a laboratory fixed-bed reactor at 800 °C, with two kinds of AAEM-loading methods. The migration and precipitation characteristics of AAEM species was evaluated by ICP-AES, while the transformation of biochar structures were analyzed by FTIR and Raman. The specific reactivity of H 2 O/CO 2 gasification biochar was determined by TGA analysis in Air at 370 °C. The results show that the stronger catalytic properties of K and Ca species in H 2 O atmosphere are obtained than that in CO 2 . The effect of K is mainly on the formation of O-containing functional groups (e.g. alcohol/phenolic-OH, aldehyde/ester C O and carboxylic COO groups) and the transformation from small ring systems to larger ones, while the catalytic effect of Ca is only to increase the proportion of large aromatic ring structures (≥6 fused benzene rings). The biochar-CO 2 reaction took place mainly at the gas-solid interface of biochar, while biochar-H 2 O one existed throughout the biochar particle. A better distribution of active sites (i.e. surface K/Ca species and O-containing groups) on biochar surface would result in the high specific reactivity of biochar during gasification. [ABSTRACT FROM AUTHOR]

The high contents of AAEM (alkali and alkaline earth metals) and sulfur in zhundong coal result in more fine particulate matter during coal combustion. In this paper, the emission of fine particulates from zhundong coal riched in AAEM-sulfur and zhunnan coal riched in aluminum-silicon was investigated in a drop tube furnace. Co-combustion of zhundong coal and zhunnan coal was further investigated to study the effect of interaction among different elements in coal on the PM formation. The size distribution, concentration and composition of the particulates were analyzed by low pressure impactor (DLPI) and scanning electron microscopy (SEM). The distribution of sodium, magnesium, calcium, iron and sulfur in fine particulates and their effects on the generation of fine particulates were obtained. The results show that the fine particulates from AAEM-sulfur rich coal combustion mainly consist of sulfates and oxides of AAEM. The amount of fine particulates from burning aluminum-silicon rich coal decreased significantly. The composition of PM 0.4 and PM 0.4+ are significantly different. Co-firing of AAEM-sulfur rich coal with aluminum-silicon rich coal has an obviously synergetic effect of reducing the fine particulates emission. The capture of AAEM and iron by aluminum-silicon compounds plays an important role in PM 10 reduction during blended coal combustion. The change of sulfur content in PM 0.4 is consistent with the change of AAEM content. [ABSTRACT FROM AUTHOR]

Lignite, a suitable feedstock for direct coal liquefaction (DCL), is usually rich in sodium and calcium species. To better understand chemical transformation of inherent sodium and calcium species during DCL, two lignites rich in sodium and calcium species were liquefied in this work. The results show that both Australia lignite (AU) and Hami lignite (HM) are preferred raw materials for DCL. After DCL, mineral matters were obviously enriched in residues (DCLR). Under all the temperatures, retention ratios of sodium species were lower than those of calcium species. One obvious transformation of calcium species was reflected in changes of organic-bound calcium species (AS-Ca) and hydrochloric acid-insoluble calcium species (HIS-Ca) in HM. During direct liquefaction of HM, the amount of AS-Ca decreased significantly and the amount of HIS-Ca increased sharply. XRD analyses of low temperature ashes of DCLR confirmed that when temperatures reached above 400 °C, kaoline in HM gradually decomposed and came to react with AS-Ca, which resulted in formation of HIS-Ca. Due to the low ash content, transformation of calcium species in AU showed unobvious tendency and only CaCO 3 was detected in DCLR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Barium modified hydroxyapatite is highly effective for glucose isomerization to fructose in ethanol. • Fructose yield of 35.4% with selectivity up to 93.5% was obtained at glucose loading of 10 wt%. • The catalyst was reused with high recovery rate and ultralow leaching of ions. • The composition, structure and activity of catalyst can be completely restored via calcination. The application of synthetic catalysts to displace costly isomerases for glucose isomerization to fructose has been a long-standing goal in biomass valorization, but current catalysts generally suffer from inferior stability and reusability. Here we show that the combination of barium modified hydroxyapatite (Ba/HAP) as catalyst with ethanol as solvent enables highly efficient and selective isomerization of glucose to fructose, affording fructose yield of 35.4% with selectivity up to 93.5% at high glucose loading (10 wt%). Moreover, the Ba/HAP catalyst was reused with high recovery rate and the leaching of ions was greatly inhibited. The composition, structure and catalytic activity of catalyst can be almost completely restored after calcination. Density functional theory simulations revealed that the formation of relatively stable BaCa 6 (PO 4) 4 O phase is beneficial to the improved catalyst stability. Simultaneously achieving high reaction efficiency and good catalyst reusability in green solvent, our study is an important step towards sustainable catalysis. [ABSTRACT FROM AUTHOR]

• The difference in gasification reactivity of digested solid char with and without AAEMs was systematically clarified. • The inherent AAEMs have promoting effect on gasification reactivity of char. • The E a value of the char after pickling increased 115.76 kJ·mol−1. • The maximum instantaneous CO concentration after char pickling was reduced by a factor of about three. Char reactivity usually determines the overall efficiency of the entire gasification process, while the presence of the alkali and alkaline earth metals (AAEMs) has a catalytic effect on char gasification. In this study, the influence of inherent AAEMs in the gasification behaviour of char was investigated. The char sample was prepared through the pyrolysis of solid digestate derived from anaerobic co-digestion of silage and dairy cattle slurry. The raw char and HCl-washed char were characterized by elemental analyzer, ICP-OES, SEM and XRD to explore their structural changes. HCl-char loses weight in the temperature range of 440–620 °C, and the weight loss percentage is significantly higher than that of char. Ash content of char is reduced by half after a pickling process. AAEMs are largely removed after char acid pickling, resulting in an increase in activation energy of the gasification reaction and a decrease in gasification reactivity, resulting in the gasification reaction time of HCl-char longer than char. Water-soluble AAEM and ion-exchange AAEM affect the evolution of carbon structure, which directly lead to char reactivity during the gasification reaction. As the carbon is consumed, the carbon microcrystalline structure of the residual carbon tends to be ordered, resulting in fewer active free carbon sites for the gasification reaction. Kinetic analysis showed that the loss and deactivation of AAEMs after char acid washing increased the average activation energy E a by 115.76 KJ/mol compared with the original char. [ABSTRACT FROM AUTHOR]

[Display omitted] • S and Cl in biomass are significantly removed after torrefaction. • AAEMs in biomass tend to transform to less-reactive forms after torrefaction. • Torrefaction inhibits the mineral vaporization in combustion, thus reduces the emission of PM 1. • PM 1-10 increases due to more retention of the metals or decreases by agglomerating into PM 10+. Torrefaction is a promising technology to scale up the utilization of biomass for power purposes. The ash-related issues during biomass combustion and co-combustion are essential to be addressed, however, on which the effects of torrefaction are seldom concerned and need in-depth and comprehensive investigation. To provide useful information related, the authors conducted a series of studies. In the present work, the particulate matter (PM) emission during combustion is focused on. Three biomasses were torrefied at a fixed-bed reactor, and the elemental release and transformation during torrefaction were characterized through chemical fractionation analysis. The combustion tests of the raw and torrefied biomass and their blends with two typical coals were conducted on a drop-tube furnace at 1300℃ in air. The PM 10 (particulate matter with an aerodynamic particle size below 10 μm) collected by a Dekati low-pressure impactor and PM 10+ (particulate matter with an aerodynamic particle size above 10 μm) collected by a Dekati cyclone were characterized by a scanning electron microscope equipped with energy dispersive spectrometer (SEM-EDS). The results indicate that torrefaction effectively reduces S and Cl in biomass while slightly reducing the alkalis. The contents of refractory elements (Mg, Ca, and Fe) are hardly influenced. Torrefaction promotes the transformation of AAEMs (alkaline and alkaline earth metals) into less-reactive forms (HCl-soluble and insoluble). The vaporization of alkalis, S, and Cl during biomass combustion is reduced and the retention of AAEMs into aluminosilicates is promoted after torrefaction. This reduces the emission of PM 1 (particulate matter with an aerodynamic particle size below 1 μm) from biomass combustion. During co-combustion, the PM emission largely depends on the combined effects of elemental vaporization, competing reactions (alkalis against Mg, Ca, and Fe), retention of metals into aluminosilicates, and sulfation of chlorides. The inhibited effect of torrefaction on mineral vaporization reduces the formation of PM 1 by condensation. The emission of PM 1-10 (particulate matter with an aerodynamic particle size between 1 and 10 μm) either increases due to the promoted retention of the metals in coarse particles or decreases by agglomerating into PM 10+. Torrefaction shows a preferable performance concerning its effects on PM emission during biomass combustion and co-combustion with coal. [ABSTRACT FROM AUTHOR]

[Display omitted] • S and Cl in biomass are significantly removed after torrefaction. • AAEMs in biomass tend to transform to less-reactive forms after torrefaction. • Torrefaction inhibits the mineral vaporization in combustion, thus reduces the emission of PM 1. • PM 1-10 increases due to more retention of the metals or decreases by agglomerating into PM 10+. Torrefaction is a promising technology to scale up the utilization of biomass for power purposes. The ash-related issues during biomass combustion and co-combustion are essential to be addressed, however, on which the effects of torrefaction are seldom concerned and need in-depth and comprehensive investigation. To provide useful information related, the authors conducted a series of studies. In the present work, the particulate matter (PM) emission during combustion is focused on. Three biomasses were torrefied at a fixed-bed reactor, and the elemental release and transformation during torrefaction were characterized through chemical fractionation analysis. The combustion tests of the raw and torrefied biomass and their blends with two typical coals were conducted on a drop-tube furnace at 1300℃ in air. The PM 10 (particulate matter with an aerodynamic particle size below 10 μm) collected by a Dekati low-pressure impactor and PM 10+ (particulate matter with an aerodynamic particle size above 10 μm) collected by a Dekati cyclone were characterized by a scanning electron microscope equipped with energy dispersive spectrometer (SEM-EDS). The results indicate that torrefaction effectively reduces S and Cl in biomass while slightly reducing the alkalis. The contents of refractory elements (Mg, Ca, and Fe) are hardly influenced. Torrefaction promotes the transformation of AAEMs (alkaline and alkaline earth metals) into less-reactive forms (HCl-soluble and insoluble). The vaporization of alkalis, S, and Cl during biomass combustion is reduced and the retention of AAEMs into aluminosilicates is promoted after torrefaction. This reduces the emission of PM 1 (particulate matter with an aerodynamic particle size below 1 μm) from biomass combustion. During co-combustion, the PM emission largely depends on the combined effects of elemental vaporization, competing reactions (alkalis against Mg, Ca, and Fe), retention of metals into aluminosilicates, and sulfation of chlorides. The inhibited effect of torrefaction on mineral vaporization reduces the formation of PM 1 by condensation. The emission of PM 1-10 (particulate matter with an aerodynamic particle size between 1 and 10 μm) either increases due to the promoted retention of the metals in coarse particles or decreases by agglomerating into PM 10+. Torrefaction shows a preferable performance concerning its effects on PM emission during biomass combustion and co-combustion with coal. [ABSTRACT FROM AUTHOR]

• The effect of AAEMs on char combustion characteristics in O 2 /CO 2 was studied. • Coal char combustion reaction kinetics were analyzed by different models. • The effect of O 2 content and heating rates on the K catalytic effect was studied. • The ignition and burnout of coal char were advanced by alkali metal potassium. The oxy-fuel combustion technology has attracted widespread attention because of its relatively low-cost and large-scale CO 2 capture. During the oxy-fuel combustion process, the low diffusivity of O 2 in CO 2 brings several difficulties on coal char combustion due to N 2 replacement with CO 2. Catalytic combustion by adding alkali and alkaline earth metals (AAEMs) is an effective way to improve the coal char combustion performance. In this work, the catalytic effects of AAEMs on coal char combustion characteristics under different conditions were studied. Besides, the kinetic parameters of char combustion were obtained by Kissinger-Akahira-Sunose, Starink, and Flynn-Wall-Ozawa methods. Results showed that compared with other AAEMs (Na, Ca, and Mg), K showed better catalytic effects on ignition, burnout, and comprehensive combustion characteristics of coal char. The promotion effect of K on the combustion performance was gradually saturated when addition ratios exceeded 1 wt%. At low O 2 concentrations or heating rates, K exhibited a strong catalytic effect on coal char combustion. Besides, K could accelerate the decrease in activation energy (E a) of coal char combustion as char conversion (α) increased. When α was 0.9, the reduced effect of K on the E a value was 13%. These results are expected to provide new insights into the improvement of coal char oxy-fuel combustion catalyzed by AAEMs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wash pretreatment can remove alkaline earth metals from biomass to improve bio-oil quality. • The different mechanisms of catalysts in catalytic cracking and hydrotreating summarized. • Analyzed the technical difficulties of bio-oil upgrading technology towards industrialization. • Hydrotreating processing can remove many heteroatomic compounds. • The removal mechanisms of sulfur and chlorine from bio-oil reviewed. This paper reviews the research progress of heteroatomic compound treatment technology in bio-oil. Bio-oil fuels are expected to be a renewable energy source instead of fossil fuels. However, the heteroatomic compounds such as oxygen, nitrogen and sulfur compounds in bio-oil can affect the combustion performance and cause environmental impact during the combustion process, so the heteroatomic compounds need to be removed. The heteroatom removal techniques are widely used in the preparation of bio-oil from biomass, including biomass washing treatments, catalytic cracking, catalytic hydrotreating, and other techniques such as adsorption denitrification and adsorption dichlorination and co-pyrolysis. And the catalytic mechanism is discussed. The removal effects of different catalysts and different methods are also compared. Many researchers are using various techniques to treat heteroatomic compounds in bio-oil, so it is necessary to summarize and analyze them to provide a reference for future research directions. [ABSTRACT FROM AUTHOR]

• Olivine and feldspar exhibit similarities regarding their ash layer formation. • Formation of ash layers is more pronounced on convex areas of bed particles. • A layer of Mn and Fe causes the particles to exhibit an oxygen carrying ability. • Alkali and alkaline earth metals are present on the surface of the bed particles. Olivine and alkali-feldspar were utilized in separate campaigns in an indirect dual fluidized bed gasification campaign with woody biomass as fuel. After three days, both bed materials were reported to be active towards tar removal and exhibited oxygen-carrying abilities and had formed an ash layer consisting of an outer ash deposition layer and an inner interaction layer. X-ray microtomography analysis concluded that a preferred deposition of ash happens onto convex regions of the bed particles, which results in an increase in thickness of the ash layer over convex regions. This effect is most pronounced for the outer layer which is a product of ash deposition. The inner layer exhibits a homogeneous thickness and is probably formed by interaction of Ca from the outer layer with the particles. Transmission electron microscopy revealed the presence of Fe and Mn on the surface of the particles in a solid solution with Mg. The oxygen-carrying effect which is found for aged particles is therefore attributed to the presence of Fe and Mn on the surface of aged particles. Alkali were found on the surface of both particles which are likely contributing to the catalytic activity of the material towards tar removal. [ABSTRACT FROM AUTHOR]

Simulated solid waste was incinerated in a fixed bed, while continuously collecting volatized Pb and Cd to investigate the dynamic volatilization behavior. The dynamic data revealed the reducing atmosphere generated by the fixed bed as the main reason for the lower initial volatilization temperatures of Pb and Cd compared to PbO and CdO melting points during chlorine-free incineration. CdO was easier to reduce than PbO; consequently, Cd volatilized stronger than Pb in the chlorine-free fixed bed. However, CdO volatilization was expected to be weaker than PbO volatilization in an air atmosphere. In contrast to the reduction in a fixed bed, the addition of PVC led to indirect chlorination of Pb and Cd at 300–400 °C and 400–500 °C, respectively and their volatilization was significantly enhanced via chlorination. NaCl directly chlorinated Pb and Cd at comparatively high temperatures of 800–900 °C and 700–800 °C, respectively via involvement of SiO 2 and Al 2 O 3 . Moreover, CaO absorbed HCl from PVC, resulting in volatilization inhibition of Pb and Cd at a temperature below 700 °C. However, chlorine was released at a higher temperature. Furthermore, CaO had no effect on NaCl-induced volatilization enhancement of Pb and Cd. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxygen vacancies in δ-MnO 2 were regulated by alkaline earth metal doping. • The oxygen vacancy formation energy of δ-MnO 2 is reduced due to Ba doping. • The lattice oxygen is activated by the formation of oxygen vacancies. • Ba doped δ-MnO 2 has more oxygen vacancies and better toluene catalytic activity. Oxygen vacancy engineering is a proven method to promote catalytic performance. In this paper, a series of alkaline earth metal-doped layered MnO 2 catalysts were prepared to modulate the oxygen vacancies in MnO 2 and applied to catalytic oxidation of toluene at low-temperature. Various characterizations and DFT calculations show that the alkaline earth metals enter the MnO 2 lattice, leading to the distortion of the lattice and the formation of oxygen vacancies, which eventually lead to the activation of the lattice oxygen. Ba-doped MnO 2 shows the highest content of oxygen vacancies and the highest lattice oxygen activity, thus exhibiting the best low-temperature catalytic performance for toluene (T 90 = 182 °C). This work provides an innovative approach for the construction of oxygen vacancies on high-performance catalysts for toluene oxidation. [ABSTRACT FROM AUTHOR]

[Display omitted] • HTC-derived algal hydrochar was recovered via filtration with and without a solvent. • The two recovery methods greatly affect the yields and properties of hydrochar. • Under identical conditions, filtration without a solvent gives higher hydrochar yield. • The higher hydrochar yield is attributed to the biocrude retained on its surface. This contribution reports the effects of product recovery methods on the yields and properties of hydrochars produced from hydrothermal carbonization (HTC) of algal biomass. A slurry of Chlorella vulgaris with 10 wt% of solid loading was hydrothermally carbonized at 180 – 220 °C with holding time of 15 and 60 min. The resulting hydrochars were recovered by two prevailing methods, namely direct filtration and dichloromethane (DCM)-aided filtration. The results indicate that, under identical HTC conditions, compared with DCM-aided filtration, direct filtration always results in higher hydrochar yield because of the biocrude retained on its surface. The presence of residue biocrude in the hydrochars from direct filtration further leads to considerable differences in their properties, as compared with their counterparts from DCM-aided filtration. Specifically, under identical HTC temperature and holding time, DCM-aided filtration yields hydrochars of lower volatile matter contents but higher fixed carbon and ash contents, as compared with the hydrochars from direct filtration. Direct filtration generally recovers hydrochars of greater higher heating values and energy-based yields as compared to DCM-aided filtration. The product recovery methods show considerable impacts on the concentrations of Na, K, Mg, and Ca and their retentions in the hydrochars at 220 °C for 60 min, with higher concentrations and retentions of these elements being observed in the hydrochars from DCM-aided filtration. The hydrochars at 220 °C for 15 and 60 min from DCM-aided filtration show higher specific reactivity of 0.040 – 0.058 min−1 and 0.066 – 0.096 min−1 at hydrochar conversions of ≤ 82 % and ≤ 78 %, respectively, as compared with their direct-filtration counterparts, due to their higher concentrations of catalytic alkali and alkaline earth metals. These findings highlight the importance of considering product recovery methods when comparing the yields and properties of hydrochars from HTC of algae reported in the literature. [ABSTRACT FROM AUTHOR]

Uranium is one of the typical naturally occurring radioactive materials in coal. The release and speciation transformation of uranium was investigated at various combustion temperatures, and the thermodynamic modelling was performed to complement the experimental work. The results showed that the uranium release ratio did not increase consistently with the combustion temperature increasing, where the highest release ratio occurred at 500 °C. At the temperature range of 500–900 °C, the uranium release ratio obviously decreased, which could be attributed to the formation of uranate with the interaction of alkaline/alkaline-earth metal compounds in coal. However, some of the thermal unstable uranate was decomposed and released at the temperature above 1000 °C, while part of them remains stable in the combustion product even when the sample was heated at 1200 °C. Further, the interaction mechanism of uranium and alkaline/alkaline-earth metals during coal combustion was proposed based on the experimental and modelling results. This study will provide valuable information for understanding the primary factors and processes that affect the release of uranium during coal combustion. [ABSTRACT FROM AUTHOR]

Zhundong coal is one of the most important coals in China due to its huge reserve, but it causes severe fouling and slagging problems when it is burnt in boilers for its high AAEMs (alkali and alkaline earth metal species) contents. Accurately determination of the occurrence modes and contents of AAEMs in Zhundong coals is a necessary step to overcome the ash-related problems. Nowadays, different researchers used different methods or procedures to determine AAEMs in Zhundong coals, and the data were scattering. Based on a series of experiments on the effects of extraction conditions, an improved extraction method with clearly defined conditions for each extraction step was proposed. 0.1 mol/L NH 4 Cl (pH = 8.5) instead of 1 mol/L NH 4 OAc (pH = 7) was used to extract the exchangeable AAEMs in Zhundong coals to avoid the high solubility of carbonates in the extraction solution. The improved method was more accurate and took much less time than the conventional one. With the proposed extraction method, the occurrence modes and contents of AAEMs in three Zhundong coals were measured. The results revealed that Na is mainly water soluble (Na w /Na total = 50–85%) which is halite or in the form of surface bound Na + , while Ca and Mg are mainly acid soluble (Ca ac /Ca total = 60–90%, Mg ac /Mg total = 45–90%) which are carbonates together with a little amount of sulfates. Exchangeable AAEMs organically bonded to the coal matrix are not the main occurrence mode of AAEMs. Acid insoluble Ca-species could be rankinite. The amounts of AAEMs in the same occurrence mode could be remarkably different among coals from different Zhundong district. The improved sequential extraction method can be extended to determine AAEMs in high carbonate-containing coals. [ABSTRACT FROM AUTHOR]

[Display omitted] • Global kinetic parameters were determined using isoconventional, generalized master plot, model based, and Frazer-Suzuki deconvolution methods. • Lumped kinetic model applied to Organosolv lignin pyrolysis, and calculated kinetic parameters showed lignin to liquid was predominant pathway. • Effect of AAEMs on kinetic, and product characterization on Organosolv lignin pyrolysis analyzed systematically. • 2.0 wt% Mg loading was the strongest effect on Organosolv lignin pyrolysis. The pyrolysis characteristics and kinetics of Organosolv lignin from pine trees were investigated using isoconventional, generalized master plot, model-based, and Frazer-Suzuki deconvolution methods. With these approaches, the activation energies of Organosolv lignin pyrolysis were determined to be in the range of 70.11–385.58 kJ/mol. In addition, the activation energies of 3 pseudo-reactions were calculated to be 15.71, 204.49, and 32.76 kJ/mol, respectively, by the Frazer-Suzuki deconvolution method. The experimental data of Organosolv lignin pyrolysis were best fitted with the 4th power-law model (P 4) with an absolute error of 3.24 %. Entropy (ΔSo), Gibbs free energy (ΔGo), and enthalpy (ΔHo) were also calculated to understand the reaction pathways from a thermodynamic point of view. Based on the pyrolysis mechanisms proposed in this study, the reaction rate constants of different steps were determined. The primary reaction route was identified to be the pyrolysis of Organosolv lignin to liquid products such as bio-oils. Among the alkali and alkaline earth metals (AAEMs) tested, 2.0 wt% Mg showed the most effective on Organosolv lignin pyrolysis, decreasing the mean activation energy (E a) from 181.67 to 156.55 kJ/mol in the range 0 ≤ X ≤ 0.85. The compositions of gaseous and liquid products formed by pyrolysis were analyzed using a micro-tubing reactor. CO, CO 2 , and CH 4 were observed as the main gaseous products, while Organosolv lignin was primarily decomposed into phenol and guaiacol derivatives. The Organosolv lignin was also depolymerized into lower-molecular-weight (LMW) components during the pyrolysis process. [ABSTRACT FROM AUTHOR]

• The presence of AAEMs reduces the maximum weight loss rate of lignin. • The S/G ratio of lignin determines the phenolic distribution from pyrolysis. • Pyrolysis temperature also significantly impacts the phenolic distribution. • Demethoxylation and dehydroxylation of phenols occur at high temperature. The complex and diverse chemical structures of lignins pose huge challenges in understanding their pyrolysis behavior and mechanism. Herein, five representative lignins, including three organosolv lignins (corncob lignin, pine lignin, eucalyptus lignin), alkali lignin, and dealkalized lignin, were used as feedstocks in this study. Comparison of their pyrolysis behaviors, product evolutions, and mechanisms at different temperatures was investigated by using thermogravimetric analyzer coupled with mass spectrometer (TG-MS) and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The chemical structure of lignin before and after pyrolysis at different temperatures was characterized by Fourier transform infrared spectrometry (FTIR). The results show that alkali lignin and dealkalized lignins provide relatively lower maximum weight loss rates and relatively higher amounts of char, CH 4 , H 2 O, CO, and CO 2 due to the presence of alkali and alkaline earth metals. The distributions of phenolic compounds from lignin pyrolysis are related to the chemical structure of lignin, especially its S/G ratio. Moreover, the pyrolysis temperature also exerts significant effects on the distribution of phenolic compounds. Pyrolysis of corncob lignin at 300 °C achieves the effective breakage of ester linkage between p-Coumarates/ferulates and phenylpropane moieties of S units to form 4-vinylphenol and 2-methoxy-4-vinylphenol. The optimal temperature for the breakage of interunit linkages of S and/or G units in lignin is 500 °C. The syringol-type compounds can be converted into guaiacol-type compounds via demethoxylation reactions at 500 °C. The syringol-type and guaiacol-type compounds can be further converted into phenol-type compounds and aromatics by demethoxylation and dehydroxylation reactions at 900 °C. These findings can guide the development of novel pyrolysis processes of lignin for the selective production of specific phenolic compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • KCl, NaCl and CaCl 2 affects the catalytic activity of V 2 O 5 -WO 3 -TiO 2 in NH 3 -SCR. • KCl has the greatest effect on surface acidity, V5+/(total V) and O 2 2− surface ratio. • The replacement of WO 3 by Nb 2 O 5 enhanced the activity and KCl tolerance. • VNbTi exhibits higher surface acidity than VWTi before and after KCl poisoning. V 2 O 5 -WO 3 /TiO 2 catalysts are widely used to reduce NO x emissions from municipal solid waste incineration. However, the flue gas always contains different alkali and alkaline earth metal chlorides. In this work, we compared the effect of KCl, NaCl and CaCl 2 on V 2 O 5 -WO 3 /TiO 2 catalyst for the NH 3 Selective Catalytic Reduction of NO x , and we aim to improve the tolerance of the catalyst by replacing WO 3 with Nb 2 O 5. It was found that KCl has the greatest poisoning effect, resulting in a severe decrease in the surface acidity, redox performance, V5+/V4+ ratio and surface adsorbed oxygen. The replacement of WO 3 with Nb 2 O 5 improved the activity and KCl tolerance of the catalyst owing to the improvement of surface acidity, redox performance, V5+ ratio and surface adsorbed oxygen. This may be due a more favorable interaction of K+ with Nb 2 O 5 than with V 2 O 5. In-situ DRITFS experiments showed that alkali (and alkaline earth) metal ions favor the transformation of adsorbed NO 2 species into stable nitrates and nitrites. However, the replacement of WO 3 with Nb 2 O 5 would inhibit the formation of these stable species owing to an electronic effect of the promoter. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste activated carbon was recycled for H 2 production. • Synergistic effects of coke properties and reaction temperature were investigated. • Coke samples pyrolyzed at 400 °C and 500 °C exhibited higher gasification reactivity. • Increasing the gasification temperature is beneficial to H 2 production to an extent. • Coke pyrolyzed at 500 °C showed the highest degree of disorder and carbon activity. The gasification of coal water slurry represents a promising way to recycle waste activated carbon. Here, the synergistic effects of physico-chemical properties and reaction temperature on the gasification of coal-waste activated carbon-slurry coke for H 2 production were investigated. The results showed that the coke samples pyrolyzed at 600 °C and 700 °C exhibited larger crystallite sizes and lower gasification reactivity, while those pyrolyzed at 400 °C and 500 °C showed higher gasification reactivity. In addition, the coke sample pyrolyzed at 500 °C achieved the highest H 2 yield of 3051 mL, at a gasification temperature of 1200 °C. Overall, increasing the gasification temperature is beneficial to H 2 production to an extent, but that too high a temperature may also inhibit the reaction. The alkali and alkaline earth metal elements present in the coke samples pyrolyzed at 400 °C and 500 °C showed stronger catalytic activity towards gasification, with the sample pyrolyzed at 500 °C exhibiting the highest degree of disorder and carbon activity, as its disordered carbon lattice increases the defects in the microcrystalline structure, which facilitates contact between carbon and steam molecules. [ABSTRACT FROM AUTHOR]

• High biocoal mass (∼80%) and carbon (˃88%) yield can be were obtained at 260 °C. • Biocoals atomic ratios and calorific values were close to those of sub-bituminous and high volatile matter coals. • High removal rates were achieved for Na, K, Mg and Ca. • Liquid phase contains phenolics. • Low gas yield of mainly CO 2. Lignin from pulping is recovered in a wet form, making it ideal for hydrothermal carbonisation (HTC). This study investigates the effects of temperature (200–280 °C), residence time (1–6 h), and water to biomass mass ratio (2:1–6:1) on the composition of the resultant biocoal and the extent of alkaline and alkaline metal removal during HTC of pine Kraft lignin (PKL). Consistent with studies on other biomass materials, temperature exhibited the most significant effect on biocoal yield and properties, followed by residence time showing a marginal effect and varying the water to lignin mass only affecting alkaline and alkaline earth metals removal. Biocoal yields were in the range of 76–95 % (80–97 % on a carbon basis) and, compositionally, the biocoal obtained corresponded to sub-bituminous (220–260 °C) and high volatile bituminous coals (280 °C). Gas yields are low with the gas comprising mainly CO 2 (98 v/v). The optimum temperature, time and biomass to water ratio for alkaline and alkaline earth metals removal was 260 °C, 3 h and 5:1 under which 93–95 % for sodium (Na) and potassium (K) and 75–80 % for magnesium (Mg) and calcium (Ca) removal were achieved. Solid-state 13C Nuclear Magnetic Resonance (NMR) revealed that during HTC, the oxygen-containing bonds of esters, ethers, and carboxylic groups were dissociated to produce lower-molecular weight including phenolic compounds dissolved in the process water. These findings have shown that the HTC is a promising alternative thermochemical route for coalification of wet PKL to a low ash coal-like fuel similar to sub-bituminous coal in rank that has potential applications for carbonisation. [ABSTRACT FROM AUTHOR]

• Biochar samples produced from biomass and lignocellulosic components were studied. • The gasification activation energy of biochar ranged from 109.8 to 196.1 kJ/mol. • Lignin was the most active biomass component determining the biochar reactivity. • Modelled Biochar with 16% cellulose, 24% xylan and 52.5% lignin had the best performance. Biochar can become a renewable substitute to coal in the future's energy mix. This work aims to investigate the optimization of reactivity of biochar samples derived from biomass (Miscanthus) and its lignocellulosic components (i.e. cellulose, hemicellulose and lignin) by studying the material characteristics, composition, thermal behavior and interaction during the CO 2 gasification process. For biochar production, the yield increased with lignin content in the biomass, but high lignin content reduced biochar's porous structure. The conversion characteristic was gradually stimulated by increasing the gasification temperature and heating rate, and the lignin biochar (LB) reactivity was the most promoted. High lignin content was favorable for improving the biochar reactivity. The reactivity of the xylan biochar (XB) was attributed to the high content of alkali and alkaline earth metals, while the activity of the cellulose biochar (CB) was due to the rich porous structure. The activation energy of biochar samples gasification reaction ranged from 109.8 to 196.1 kJ/mol, and the values decreased with the increase of carbon conversion rate. Modelled biomass with 32.5% cellulose, 15% xylan and 52.5% lignin was considered the optimal feedstock to make biochar because of the its low activation energy and high gasification reactivity. [ABSTRACT FROM AUTHOR]