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• Co-gasification of sludge mixture in SCW is studied by MD method. • Reaction order of different components in SCW is revealed. • Presence of alanine improves the gasification efficiency of lignin. • Effects of SCW mass fraction and temperature are studied. The supercritical water gasification (SCWG) technology is a promising method for the disposal and utilization of sewage sludge. As a mixture with various components, detailed studies on the co-gasification mechanism of sewage sludge in supercritical water (SCW) are needed. In this paper, three typical components, namely, α-O-4 structured lignin (C 20 H 24 O 6), triglyceride (C 9 H 14 O 6), and alanine (C 3 H 7 O 2 N) are selected to present the sludge mixture. The detailed SCWG processes of these components under different conditions are simulated by using reactive force field (ReaxFF) molecular dynamics method. The three components first undergo their own cleavage in SCW, and the cleavage order is C-O-C bond breakage of triglyceride, ether bond detachment of lignin and deamination of alanine. The order of further gasification is triglyceride, alanine, and then benzene ring segments of lignin. The presence of alanine improves the gasification efficiency of lignin, and thus increases the overall gasification of the system. The SCW mass fraction increases the production of H 2 but decreases that of CO. SCW mass fraction of 66 %–81 % is suggested for the simulation cases. In addition, the SCWG process is highly temperature-dependent because of the high energy needed for opening the benzene rings of lignin, but a much higher temperature above ring-opening temperature cannot further increase the gasification efficiency. [ABSTRACT FROM AUTHOR]

• Co-gasification of sludge mixture in SCW is studied by MD method. • Reaction order of different components in SCW is revealed. • Presence of alanine improves the gasification efficiency of lignin. • Effects of SCW mass fraction and temperature are studied. The supercritical water gasification (SCWG) technology is a promising method for the disposal and utilization of sewage sludge. As a mixture with various components, detailed studies on the co-gasification mechanism of sewage sludge in supercritical water (SCW) are needed. In this paper, three typical components, namely, α-O-4 structured lignin (C 20 H 24 O 6), triglyceride (C 9 H 14 O 6), and alanine (C 3 H 7 O 2 N) are selected to present the sludge mixture. The detailed SCWG processes of these components under different conditions are simulated by using reactive force field (ReaxFF) molecular dynamics method. The three components first undergo their own cleavage in SCW, and the cleavage order is C-O-C bond breakage of triglyceride, ether bond detachment of lignin and deamination of alanine. The order of further gasification is triglyceride, alanine, and then benzene ring segments of lignin. The presence of alanine improves the gasification efficiency of lignin, and thus increases the overall gasification of the system. The SCW mass fraction increases the production of H 2 but decreases that of CO. SCW mass fraction of 66 %–81 % is suggested for the simulation cases. In addition, the SCWG process is highly temperature-dependent because of the high energy needed for opening the benzene rings of lignin, but a much higher temperature above ring-opening temperature cannot further increase the gasification efficiency. [ABSTRACT FROM AUTHOR]

In China, the generation of municipal solid waste (MSW) incineration solid residues is expected to increase significantly in the future. Because of ever-increasing generation rates and the concentrations of potentially hazardous heavy metals, which may endanger the ambient environment, these solid residues are of particular concern. Thus, such issues have necessitated the study of the characterization of these solid residues. A detailed characterization of five samples of different type of ashes, collected from two types of MSW incinerators located in Shenzhen (southern China), was carried out in terms of chemical composition, morphology, mineralogy and leaching behavior. Results of chemical analysis and leaching tests suggest that the MSW incineration fly ash must be classified as hazardous waste and should be properly managed. Therefore, the results of this characterization would contribute to the development of adequate waste management strategies. [Copyright &y& Elsevier]

[Display omitted] • Quick measurement method of three components was established based on PT-TGA. • The method can be applicated with high heating rates up to 300 °C/min. • The time for three-component content measuring test can be as short as 3 min. • Maximum deviation of relative contents of three components was less than 3.32%. Cellulose, hemicellulose, and lignin are the major components of lignocellulosic biomass, and fast and accurate measurement of the three components' content is beneficial for the efficient application of biomass. However, the current chemical dissolution and titration method was tedious and time-consuming. In this study, a quick determination method of three components in biomass was developed for determining their contents based on a photo-thermal thermo-gravimetric analyzer (PT-TGA). Cellulose was modeled using a single F1 model, while hemicellulose and lignin were fitted with two consecutive processes according to their pyrolysis characteristic with F2 and F1 models. Using the kinetic parameters obtained from the fast pyrolysis of cellulose, hemicellulose and lignin on the PT-TGA, the contents of the three components in biomass samples were calculated by fitting the DTG curves with different peaks. Under the heating rate of 300 °C /min, the relative content deviation of the three components of rice straw was less than 2.00 % with the measurement time within 3 min. Furthermore, coconut shell and pine were used to verify that the maximum difference determined by the kinetic fitting method and the chemical method was only 3.32 %, demonstrating that the method could reliably and rapidly measure the contents of the three components in lignocellulosic biomass. This study provided a fast and effective method for determining the relative content of biomass components. [ABSTRACT FROM AUTHOR]

[Display omitted] • Activation of bio-oil impregnated wood with ZnCl 2 forms more activated carbon (AC) via condensation. • Impregnation of bio-oil hinders infiltration of ZnCl 2 and reduces overall specific surface area. • Activation of bio-oil impregnated wood with K 2 C 2 O 4 generates more pores but diminishes AC yield. • Additional aliphatic structures from impregnated bio-oil facilitate pore formation via intensified cracking with K 2 C 2 O 4. • More mesopores from impregnating bio-oil render AC superior performance of phenol adsorption. Bio-oil contains abundant aliphatic organics, which can be used to impregnate a biomass feedstock for increasing aliphatic content, as aliphatics are important for pore development in activation. Herein, impregnation of homologous bio-oil to spring jasmine wood (SJW) and further activation of the impregnated sample (SJW-oil) with ZnCl 2 or K 2 C 2 O 4 were conducted, aiming to explore another alternative outlet for application of bio-oil. The results showed that the impregnated bio-oil increased yield of activated carbon (AC) by 29.9 % (on SJW basis) in activation with ZnCl 2 , due to promoted condensation of organics from the impregnated bio-oil. Nevertheless, the specific surface area was reduced from 2098.5 m2g−1 in activation of SJW only to 1602.1 m2g−1 from SJW-oil, as the impregnated bio-oil suppressed infiltration of ZnCl 2 to internal structures of SJW. However, more mesopores were generated in AC-Oil-ZnCl 2 (85.9 %) than in AC-ZnCl 2 (92.5 %), originating from activation of organics in impregnated bio-oil. K 2 C 2 O 4 could easily crack organics in the impregnated bio-oil and in SJW, increasing specific surface area from 1152.2 m2g−1 in AC-K 2 C 2 O 4 to 1283.4 m2g−1 in AC-Oil-K 2 C 2 O 4. In-situ IR characterization showed formation of additional aliphatic structures from the impregnated bio-oil and also intensified cracking reactions, favoring pore developing but diminishing AC production. The impregnated bio-oil also rendered the AC with superior performance for phenol adsorption but lowered environmental impact of the activation process. [ABSTRACT FROM AUTHOR]

[Display omitted] • NaOH disrupts entangled structure in Chinese parasol (CP), releasing more volatile. • Activation of CP-NaOH increased permeability and yield of activated carbon (AC). • Activation of CP-NaOH with ZnCl 2 renders AC of more developed pores. • Reduced stability and aliphatic content form less pores in activation with K 2 C 2 O 4. • In-situ IR confirms enhanced condensation by ZnCl 2 and reduced cracking by K 2 C 2 O 4. Pore structures of activated carbon (AC) is determined not only by activation conditions but also by biomass composition. Alkaline treatment removes lignin and hemicellulose structures, which is expected to impact subsequent activation. This was investigated herein by activation of NaOH-treated Chinese parasol (CP) with ZnCl 2 and K 2 C 2 O 4 , respectively. The results indicated that pyrolysis of CP-NaOH (with NaOH treatment) enhanced pyrolysis to form more bio-oil (increase of yield by 39.0 %) but less gases (decrease by 62.5 %), due to increased mass transfer of volatiles via destructing winding structure. Activation of CP-NaOH with ZnCl 2 also generated higher yield of AC than that of activation of CP (40.5 % versus 31.5 %), because of enhanced permeability of ZnCl 2 after the NaOH treatment for catalyzing condensation of cellulose derivatives. The NaOH treatment also rendered AC-NaOH-ZnCl 2 (NaOH treatment followed by activation) with more developed pores than AC-ZnCl 2 (specific surface area: 1531.5 versus 1281.8 m2g−1), with also more abundant micropores (97.1 % versus 94.1 %), due to the higher accessibility of ZnCl 2 to cellulose structure in CP-NaOH. However, activation of CP-NaOH produced AC-NaOH-K 2 C 2 O 4 with less developed pore structure than AC-K 2 C 2 O 4 (863.2 versus1062.9 m2g−1). This was due to the lowered structural stability of AC and consequently merge of micropores from reduced content of lignin and less pores generated from cracking of aliphatic structures from partial hemicellulose removal. The in-situ IR characterization confirmed accelerated dehydration and condensation of unsaturated aldehydes/ketones in activation of CP-NaOH with ZnCl 2 and the reduced abundance of aliphatic structures and decreased intensity for cracking for generating pores with K 2 C 2 O 4. [ABSTRACT FROM AUTHOR]

Fe–Mn–Ce/γ-Al 2 O 3 granular catalyst was synthesized using the sol-gel method and then developed in the low temperature selective catalytic reduction (SCR) of NO with NH 3 . It achieved outstanding SCR activity at low temperature and also showed excellent space velocity tolerance and favorable SO 2 and H 2 O resistance. The addition of Fe obviously increased the surface area and pore volume of the catalyst, and it also strengthened the surface acidity of Brønsted and Lewis acid sites, which was beneficial with the increase of SCR activity. The TPD and DRIFT results showed that the number of Lewis acid sites on the catalyst was much more than Brønsted sites, which could facilitate the formation of coordinated NH 3 and –NH 2 species. NO could be adsorbed in the form of unstable nitrates, which could then react with the adsorbed NH 3 species directly. The most possible reaction pathway was proposed as that NH 3 was firstly adsorbed on the catalyst after the competitive adsorption, and then the formed coordinated NH 3 and –NH 2 species reacted with the gas phase NO and generated N 2 and H 2 O. That is, the SCR reaction route mainly followed the Eley–Rideal mechanism. [ABSTRACT FROM AUTHOR]

• The addition of inorganic sodium inhibits the OH generation and ignition of coal. • High sodium coal exhibits lower PAHs and soot generation during coal early stage combustion. • Pathways of cleavage of coal matrix affected by sodium are studied by DFT. • Sodium in the coal increases the energy barrier of cleavage of coal matrix in the early stage of coal combustion. Inorganic sodium in low rank coal exerts significant influence on the soot generation in the early stage of combustion. The effect of inorganic sodium on the PAHs, soot formation and OH generation of coal particle was investigated on a concentrating light heating platform using Planar Laser Induced Fluorescence (PLIF) of OH radicals and PAHs. The generation characteristics of PAHs during coal particles pyrolysis with the temperature of 500 °C and 800 °C were also investigated. Raw coal, acid-washed (AW) coal and AW impregnated with different mass ratio of NaCl (1 %, 3 % and 5 % NaCl-loaded) were studied. Theoretical calculations using density functional theory was performed to explore the effect of sodium on the conversion of small molecule to macromolecular substances during early coal combustion. The results showed that the NaCl addition inhibited the OH radical and soot generation in the early stage of coal combustion, as demonstrated by the reduced OH intensity, and decreased soot intensity by observing the flame luminosity for the NaCl-loaded coals, compared with AW coal. Simultaneously, the PAHs generation was significantly reduced for NaCl-loaded coals, both at the early stage of coal combustion and under pyrolysis conditions, compared with AW coal. The quantum chemistry calculation revealed that the formed C-Na structure enhanced coal structural stability, making the chemical bonds less prone to cleavage, thereby inhibiting the volatile and PAHs release during the early stage of coal combustion. On the other hand, the released Na+ can catalyze the addition reactions of small ring PAHs (naphthalene, naphthalene derivatives) to larger ring PAHs (phenanthrene, pyrene), which would promote the PAHs and soot generation in homogeneous reactions, explaining the highest PAHs with 3-to-5 rings for 5 % NaCl-loaded coal among NaCl-loaded coals. The above two kings of reaction pathways were related to soot formation, but considering the results of reduced soot yield after NaCl addition, the former dominated. Furthermore, the results from the two pathways also illustrated that the Na inhibit the OH formation, which was corresponding to the decreased OH intensity for NaCl-loaded coals, as detected by OH-PLIF, and thus was detrimental to soot consumption. Therefore, the presence of Na in the early stage of combustion inhibited the release of volatiles and PAHs, which was the main reason for the decreased soot generation amount of NaCl-loaded coal. [ABSTRACT FROM AUTHOR]

• Heavy components in the condensed volatiles from amino acids pyrolysis were characterized. • Stable free radical intensity in char shows positive correlation with tar yields and heavy components average mass. • Heavy components from alanine were developed based polypeptide formation followed by dissociation of small groups. • Phenylalanine and tryptophan prefer to crack into radicals like C 8 H 7 N/C 12 H 10 N 2 ·and then recombine together. • Heavy components from the three amino acids all decreased above 550 °C, but the reasons are different. Heavy components, comprised of molecules with a substantial molecular mass, are essential constituents within volatiles. Within these molecules, nitrogen-containing compounds have a tendency to undergo transformation into coke during thermal treatment, exerting a substantial impact on the efficient and secure utilization of biomass. Three amino acids- alanine with an aliphatic structure, phenylalanine with additional aromatic features, and tryptophan with an extra heterocyclic ring were selected as model compounds, individually subjected to pyrolysis within the temperature range of 450 to 650 °C. The evolution of heavy components and the associated reaction mechanisms were comprehensively explored through extensive characterization and network analysis. The results showed that alanine transformed into heavy components mainly through dehydration followed by dissociation of CH 2 and CH. In contrast, phenylalanine and tryptophan tended to undergo fragmentation into C 8 H 7 N· and C 12 H 10 N 2 · derivatives, subsequently recombining to form heavy molecules. As the temperature increased, heavy components in alanine-derived volatiles monotonously decreased due to elimination reactions and the breaking of C–C bonds. Conversely, heavy components in phenylalanine and tryptophan initially increased and then decreased due to the enhanced cracked fragments, along with the competitive relationship between aromatization and polymerization reactions. For all three amino acids, there is a positive correlation among the average mass of heavy components, tar yield, and the intensity of permanent free radicals in the char. This implies that we may rapidly predict the evolutionary patterns of heavy components and tar through free radical detection. HCN dissociation is mathematically identified as a pivotal reaction in heavy component evolution, irrespective of amino acid type, possibly unveiling an important pathway for NOx formation. This study shows substantial theoretical significance for the eco-friendly and efficient conversion of nitrogen-rich biomass. [ABSTRACT FROM AUTHOR]

[Display omitted] • Application of biochar from food waste pyrolysis in heavy metals adsorption was investigated. • Food waste biochar has excellent Cu(II) and Cr(III) adsorption performance. • The competitive effect of Cr(III) on Cu(II) is obvious in the mixed system. • The leaching toxicity of adsorbed biochar was low. • Multiple reaction mechanisms of heavy metals adsorption by alkaline earth metal ion in biochar. Enhancing biochar's adsorption and solidification performance in compound-polluted aqueous solutions remains a crucial task for achieving the cost-effective removal of heavy metals from water bodies. The study examined the removal performances and mechanisms of Cu(II) and Cr(III) using biochar prepared from food waste at temperatures of 350 °C, 450 °C, and 550 °C (FWB-350, FWB-450, and FWB-550). FWB-450 exhibited the highest overall effectiveness in adsorbing Cu(II) and Cr(III), demonstrating the adsorption capacity (Q e) of 40.283 and 21.456 mg/g in single-solution, respectively. Thermodynamic parameters indicate that the adsorption process involves physical and chemical reactions involving heat absorption. The impact of Cr(III) on the adsorption of Cu(II) is more apparent in the mixed competitive system. The pH, the oxygen-functional groups and carbonate ion quantity of FWB are crucial in improving Cu(II) and Cr(III) adsorption by affect the hydrolysis, complexation, and ion exchange processes. The presence of alkaline earth metal ions in FWB, like Ca(II), aids in the elimination of Cu(II) and Cr(III) through ionic precipitation and ion exchange, correspondingly. Furthermore, FWB adsorbed with Cu(II) and Cr(III) is relatively less hazardous than solid waste. The study validates the resource utilization of FW and its potential application of biochar in heavy metal adsorption. [ABSTRACT FROM AUTHOR]

• Effects of ex-/in-situ catalysis on bio-oil pyrolysis were investigated. • Less coke and more gas were accomplished by pyrolysing bio-oil with Ni/Al 2 O 3. • Cross-linkage structures formation in coke are influenced by in-situ catalysis. • Coke formation was suppressed via pre-elimination of oxygen-containing groups. Bio-oil can be converted into syngas, chemicals, and carbon materials via thermochemical and/or catalytic conversion routes. However, coking remains a significant challenge during the heating of bio-oil. In this study, we investigated the influence of pre-blending Ni/Al 2 O 3 and bio-oil in an in-situ catalytic pyrolysis process on the coking behaviours of bio-oil. Our results indicate that the presence of Ni/Al 2 O 3 significantly reduces coke yield and increases gas yield (for example, by a 14.2 % reduction in coke and a 44.1 % increase in gas at 700 °C). This is attributed to the suppression of the cross-linking reactions responsible for coke formation through the pre-elimination of O-containing groups into CO and CO 2. Additionally, pre-blending of Ni/Al 2 O 3 is highly desirable for transforming or stabilising the highly reactive substances in the early pyrolysis stage of bio-oil, minimising their tendency to polymerise. Furthermore, the presence of Ni/Al 2 O 3 facilitates the cracking of C–H bonds and self-reforming of bio-oil, increasing H 2 production (which is increased by 42.3 % at 700 °C), thereby promoting the breakage of side chains of lignin-derived aromatics and the hydrogenation of unsaturated structures, suppressing the formation of small aromatic systems in coke (<6 rings). Nevertheless, enhanced formation of alkyl-aryl C–C bonds during aromatisation leads to more condensed coke structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Much more coke forms in upper-layer Ni/KIT-6 in steam reforming of acetic acid. • Used Ni/KIT-6 is more effective to inhibit coking than fresh counterpart Ni/KIT-6. • More O-containing species form over used catalyst via influence from original coke. • O-containing species pass down to lower layer and promote polymeric coke formation. • Used catalyst in upper layer reduces the stability and crystallinity of coke. Deactivated or coked catalyst from steam reforming may not always be treated as a solid waste, which might be potentially used as a sacrificial or protective layer of catalyst for reducing coke formation of catalyst in the lower bed in the same steam reforming process. In this study, steam reforming of acetic acid over Ni/KIT-6 at 600 °C was conducted with used Ni/KIT-6 in upper layer and freshly reduced Ni/KIT-6 in lower layer (dual-bed system). The results suggested that significantly more coke (3 to 4 times) formed on upper-layer catalyst (used or fresh catalyst) than on lower-layer fresh catalyst. The upper-layer used catalyst was more effectively than counterpart of fresh catalyst for mitigating coking in lower-layer catalysts. The in-situ IR technique suggested that carbonaceous species on the used catalyst impacted or reacted with the intermediates newly formed, generating more oxygen-containing species with functionalities like C O C and C O of anhydride or ketones/aldehyde form. These oxygen-containing species could polymerize/condense and pass down to the lower bed, forming more polymeric coke of lower thermal stability. Differently, more unsaturated hydrocarbon species formed on the upper-layer fresh catalyst, making the coke of highly aromatic nature with a higher thermal stability and crystallinity. Additionally, modification of reaction intermediates with the used catalyst in upper layer also formed carbon nanotubes of irregular structures with coarse surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • Formation and evolution process of PFRs during biomass pyrolysis was investigated. • Effect of biomass property and pyrolysis temperature on the PFRs was clarified. • Relationships between PFRs characteristics and chemical structure were established. • Three-stage evolution mechanism of PFRs in biochar during pyrolysis was revealed. The persistent free radicals (PFRs) in biochar can play a crucial role during biochar's utilization, but the formation and evolution mechanism of PFRs in biochar are poorly understood because of biochars' element specificity and chemical structure complexity. In order to further understand the formation and evolution mechanism of PFRs, the PFRs characteristics, chemical structure and element composition of six types of biomasses were investigated. The results revealed that the changing trend of the PFRs types, concentration and line width with pyrolysis temperature is similar for all six feedstocks. The difference in the feedstocks' properties just affects the absolute value of PFRs' characteristic parameters. The arrangement and combination of elements and carbon skeleton structure in biochar determine the evolution of PFRs in the pyrolysis process. Additionally, the (H + O)/C atomic ratio of the biomass feedstock and the content of substitutional groups on aromatic rings were found to influence the types of PFRs in biochar. When biochar has a similar O/C atom ratio, a higher H content can reduce the carbon-centered PFRs in biochar. Besides, the reduction in O element content contributes to a decrease in line width due to the reduction in the effect of heteroatoms. The good correlation between O/C atomic ratio, H/C atomic ratio, chemical structure and PFRs characteristics can be used to predict the PFRs characteristics. Combining the changing characteristics in PFRs concentration and carbon skeleton structure of biochar, a three-stage model of PFRs formation and evolution was constructed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Identifying ZnOx interfacial migration and synergies with active alloyed Cu 5 Zn 8. • Methanol induction resulted in abundant CuZn-ZnO electronic modulation interfaces. • The CuZn-ZnO synergy enhanced dissociation of H 2 O and dehydrogenation of CH 3 O. A highly durable non-noble metal catalyst like copper for high-temperature methanol steam reforming is necessary for a compact hydrogen reactor. Herein, deactivation of copper-based catalysts with strong metal-support interaction is extremely sluggish even at 550 °C when using a selective chemical reduction approach paired with various induced activation procedures. The adsorbate methanol could enhance the migration of ZnOx onto the Cu and increase the number and electronic modulation of high-activity CuZn alloy sites. The Zn pre-deposited on the Cu surface induces continuous morphology and structural reorganization of the catalytic surface, which constantly refreshes the catalyst surface. The adsorbate methanol led to abundant CuZn alloy-ZnO synergism, which sped up the dissociation of·H 2 O and the dehydrogenation of *CH 3 O in accordance with the density functional theory and, ultimately, exhibited the highest methanol conversion (99.55 %) and hydrogen yield (97.73 %) compared to the hydrogen induction. [ABSTRACT FROM AUTHOR]

Abstract: When predicting the variation of pore structure during O2/CO2 combustion of coal chars using the random pore model (RPM), it is impossible to calculate exactly the structure parameter ψ from the pore characteristics. The values of structure parameter ψ, which were calculated based on its fractal feature at various carbon conversions, should be almost constant. However, this investigation exhibited a drastic increase of ψ at the end of combustion reaction. In this work, structure parameter ψ of the RPM was modified according to the experimental analysis and a new model, fractal random pore model (FRPM), was constructed. Compared with other models such as RPM, discrete random pore model (DRPM), the Struis model (Model I) and the Liu model (Model II), it was found that fractal random pore model was more accurate to describe coal chars combustion, especially at higher conversions. Using the FRPM, O2/CO2 isotherm combustion of coal chars were analyzed at different temperatures. [ABSTRACT FROM AUTHOR]

• The presence of CO in flue gas inhibited the NH3-SCR performance of the MnSm/Ti catalyst. • Carbonate, bicarbonate, and bridged formate were formed over the MnSm/Ti catalyst. • The introduction of Co suppressed the adsorption of CO over the MnSmCo/Ti catalyst. • Carbonate formed over MnSmCo/Ti catalyst was readily decomposed with a low energy barrier. The existence of carbon monoxide (CO) in industrial boilers flue gas can suppress the performance of the selective catalytic reduction with NH 3 (NH 3 -SCR) for NO x removal at low temperatures over the Mn-based catalyst, and the related mechanism is needed to be revealed for improving the NH 3 -SCR performance. In this work, the effects of CO on the NH 3 -SCR performance over MnSm/Ti catalyst were studied, and the CO tolerance of the catalyst with cobalt (Co) modification at low temperatures was evaluated. The DFT calculations were performed to reveal the mechanism for the modification of Co over the MnSm/Ti catalyst. The NO x conversion for MnSm/Ti catalyst decreased by 15.2%-21.4% at 150–300 ℃ due to the presence of CO in the NH 3 -SCR reaction atmosphere. After introducing Co into MnSm/Ti catalyst, the NO x conversion for MnSmCo/Ti catalyst only decreased by 8.9%-13.8% at 150–300 ℃ with the presence of CO. It was evidenced that the CO tolerance of the MnSm/Ti catalyst was enhanced with the Co modification. The characterizations of catalysts revealed that the adsorptions of NH 3 and NO over the MnSm/Ti catalyst were inhibited by the presence of CO in the mixed atmosphere. Furthermore, the presence of CO in the flue gas resulted in the formation of carbonates, bicarbonates, and bridging formate on the surface of the MnSm/Ti catalysts, which would cause a decrease in the content of Mn4+ and O α on the surface of the catalyst surface. Introducing Co into MnSm/Ti catalyst could enhance the adsorption of NH 3 by forming more Lewis acid sites over the MnSmCo/Ti catalyst. The contents of Mn4+ and O α over MnSmCo/Ti catalyst were increased via the strong electronic interaction between Co ions and Mn ions. DFT calculations proved that the adsorption of CO over the catalyst was suppressed by the modification of Co with the change of the adsorption energy of CO from −167.25 kJ/mol to −53.82 kJ/mol. Additionally, the Co modification facilitated the decomposition of the carbonate formed over the catalyst with the energy barrier of related reactions decreasing from 214.67 kJ/mol to 24.45 kJ/mol, thus improving the CO tolerance of the catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Derivatives of cellulose/lignin interact in HTC, pyrolysis and activation. • Co-HTC lowers hydrochar yield as acids formed aid depolymerization. • Cross-polymerization of volatiles-biochar forms more π-conjugated organics. • Volatiles-char interaction creates additional pores in co-activation. • Interactions impact functionality, hydrophobicity and morphologies of the chars. Cellulose and lignin co-exist in agroforestry biomasses and their distinct structures lead to the formation of varied derivatives in their thermal conversions. This might induce interaction of these derivatives and shape the properties of resulting products. In this study, potential interaction of the derivatives from cellulose and lignin was investigated in three scenarios: hydrothermal carbonization (HTC) at 250 °C, pyrolysis at 550 °C and activation with CO 2 at 800 °C. The results indicated interactions among volatiles and between volatiles and char, influencing properties of varied chars. The co-HTC of cellulose/lignin reduced the yield of hydrochar, due to the enhanced depolymerization of feedstocks and heavy organics with the aid of carboxylic acids derived from cellulose. In converse, cross-polymerization reaction between volatiles and biochar in pyrolysis/activation formed additional carbonaceous solids, increasing the yield of biochar (by 5.5%) and activated carbon (by 12.4%) as well as large π-conjugated organics in the bio-oils. Aromatization reaction was enhanced during the co-pyrolysis of lignin/cellulose, making the biochar thermally more stable, while co-activation of mixture significantly increased the specific surface area of resulting activated carbon (889.0 m2g−1 versus 691.5 m2g−1 in theoretical average), as the volatiles of varied origins involved in activation of the biochar. Additionally, the co-HTC, co-pyrolysis and co-activation also significantly affected evolution of functionalities, hydrophobicity and morphologies of the hydrochar/biochar/activated carbon. [ABSTRACT FROM AUTHOR]

[Display omitted] • HTC of GP in SM liquid enhances hydrochar production via cross-interactions of intermediates. • Nitrogen from SM transfers to hydrochar via condensation with aldehydes/ketones. • HTC of GP in SM forms hydrochar of higher carbon content. • HTC at 260 °C promotes aromatization, minimizing mesopore in activating hydrochar. • Retained aliphatic structures in hydrochar are keys in creating developed pores. Grapefruit peels (GP) and swine manure (SM) are solid wastes that can be transformed into carbonaceous materials via hydrothermal carbonization (HTC). Nevertheless, how to effectively utilize liquid residual from HTC remains an issue. Herein, HTC of grapefruit peels (GP) in the liquid from HTC of SM was conducted at 220 to 260 °C, aiming to probe influence of SM liquid on evolution of property of hydrochar and activated carbons (AC) from subsequent activation of hydrochar. The results indicated that organics in SM liquid reacted with hydrochar, enhancing yield of hydrochar by 9.6 % at 260 °C via forming additional solid deposits. Such cross-interactions involved transfer of nitrogen-containing organics from SM liquid to the GP-derived hydrochar, consuming aldehydes/ketones and aromatization at especially 260 °C. This produced hydrochar of higher aromatic nature, thermal stability, and C/O ratio. The HTC in SM liquid at 220 °C retained abundant aliphatic structures in hydrochar and produced AC with developed pore structures (1056.7 m2/g). The superior porosity of the ACs with micro-mesopores texture rendered the good removal efficiencies (91.4 %) of Cr (VI) in aqueous solution. The ACs electrodes also showed good specific capacitance, reaching 356F g−1 at 1 A g−1 and 178F g−1 at 2 A g−1. [ABSTRACT FROM AUTHOR]

• The blending of spent SCR catalyst with coal was proposed. • Spent catalyst blended with coal could promote coal combustion. • The V and As could well solidify in the bottom ash. • The leaching of V and As in bottom ash was very low. The spent SCR catalyst as the hazardous waste would seriously affect the ecological environment and human life. In this study, a new method of spent SCR catalyst harmless treatment was proposed by blending the spent SCR catalyst with coal for combustion. The combustion characteristics of coal blending with spent SCR catalyst, melting solidification characteristics of V/As in spent catalyst, and leaching characteristics of V/As in bottom ash were explored by TG, ICP-MS, XRD, SEM analysis. The results show that the proper amount of spent catalyst blending with coal could promote coal combustion by reducing the ignition and burnout temperature of coal particles due to the catalytic effects of TiO 2. The co-combustion of spent SCR catalyst with coal could well solidify the V/As in the bottom ash. In this process, the solidification rate of V decreased but the solidification rate of As increased with the increasing of temperature. Both of V and As solidification rate decreased with the increasing of spent catalyst blending ratios. The leaching concentration and leaching rate of V and As in the bottom ash were lower than the emission standards. The leaching concentration of As and V of the bottom ash significantly decreased due to melting of bottom ash when the temperature reached to 1300 °C. When the blending ration of catalyst blending amount increased, the leaching concentration and leaching rate of V and As increased slightly due to the decreasing of the relative amount of CaO in bottom ash, which played an important roles in the solidification of V and As. [ABSTRACT FROM AUTHOR]

[Display omitted] • Micro-Raman mapping was developed to study coal heterogeneous structure. • The heterogeneity of chemical structure of coal and its pyrolytic char was revealed. • Effects of AAEMs on coal average and heterogeneous structure in pyrolysis were clarified. • A detailed influence mechanism of AAEMs on coal pyrolysis was proposed. The effects of alkali and alkaline earth metallic species (AAEMs) on the heterogeneous evolution of coal/char structure during pyrolysis are rarely investigated. In this study, micro-Raman mapping technology was developed to characterize the effects of AAEMs on the distribution and heterogeneous evolution of the chemical structure of coal/char particles on micro-scale during pyrolysis. The pyrolysis chars from raw coal, leached coal and loaded coal samples were prepared by using a thermogravimetric analyzer, and more than 300 Raman spectra for each sample were analyzed by micro-Raman mapping technology. The results indicate that the water-soluble AAEMs inhibit the release of volatiles during the whole pyrolysis process. The ion-exchangeable AAEMs promote the release of volatiles at the early stage of pyrolysis and then inhibit the release. For integral char structure evolution, water-soluble and ion-exchangeable AAEMs enhance the average relative amount of small aromatic rings obviously at the devolatilization stage and aromatization polymerization stage, respectively. Besides, both water-soluble and ion-exchangeable AAEMs firstly decrease the average relative amount of active structures obviously and then slightly. For heterogeneous evolution, at the devolatilization stage, the water-soluble AAEMs promote the crack of polyolefin and substitutional groups from active components, and the transformation of these species to small aromatic rings. Meanwhile, water-soluble AAEMs promote the breakdown of the cross-linked structures of the large aromatic ring system from inert components and decrease the heterogeneity of the chemical structure of char particles obviously. Besides, the ion-exchangeable AAEMs promote the breakdown of chemical bonds between aromatic rings and the release of the active components. At the aromatization polymerization stage, the ion-exchangeable AAEMs inhibit the condensation of small aromatic rings and increase the heterogeneity of the chemical structure of char particles. In the later stage of pyrolysis, char chemical structure tends to be stable and AAEMs have little effect on the chemical structure of char particles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni based carbon aerogel prepared from waste pomelo peel was used to crack ethanol. • High-yield H 2 was acquired over biomass based carbon aerogel with less Ni loading. • The mechanism of ethanol catalytic cracking for H 2 over Ni/CA catalyst was revealed. Hydrogen, a clean energy, has been widely used, whose preparation methods is significant for developing. Herein, carbon aerogel (CA) was prepared via hydrothermal-carbonization from waste pomelo peels to support Ni catalyst, and cracked ethanol for hydrogen production. When the reaction temperature reached 700 °C and the Ni loading rate was 2 wt%, the most effective catalytic conditions were achieved. In this situation, H 2 yield can reach 76.01 wt%. The mechanism of Ni/CA catalyst performance during ethanol cracking was revealed: The catalysts' evolution during the reaction of ethanol catalytic cracking can be divided into three stages: enhancement stage, stabilization stage, and deactivation stage. During the first stage (Enhancement stage), the pores of the catalysts developed and more Ni was exposed because of the functional group breaking and the polycondensation of carbon, which enhanced the H 2 generation. The Ni on the catalyst surface was slightly promoted in the preliminary period of the second stage (Stabilization stage) and ordered graphite fibrous carbon started to grow. These two processes kept in balance, which led to the generation of hydrogen kept increasing. As the reaction proceeded further, graphite carbon gradually blocked the pores and covered the catalytic active substances loaded on the surface. During the last stage (Deactivation stage), the performance of the catalyst had been greatly reduced by carbon deposition, and the generation of H 2 was thus inhibited. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the homogeneous formation and reduction of NO from the oxidation of CH 4 /NH 3 to understand the effect of the high concentrations of H 2 O on NO emissions. The experimental results about the effects of excess oxygen ratio, gas compositions including H 2 O, CO 2 , NH 3 and recycled NO, on NO formation and reduction were presented. The mechanism about the effects of high concentration of H 2 O and combined effect of H 2 O/CO 2 on NO formation and reduction has been discussed. The results indicates that NO formation was markedly enhanced at high concentrations of H 2 O, which were mainly attributed to the increased OH radicals with steam addition at oxygen-rich conditions. By contrast, the radicals were consumed by reduction radicals, such as CO, H, and CH i radicals, under oxygen-lean conditions. NO concentrations followed the sequence of H 2 O/Ar > H 2 O/CO 2 > CO 2 /Ar under both the oxygen-rich and oxygen-lean conditions, which meant that the highest and lowest NO emissions were recorded in Ar/H 2 O and CO 2 /Ar respectively. The combined H 2 O/CO 2 concentration accordingly exerted an effective impact on NO reduction. The results about the effect of NH 3 concentration in fuel on NO emission showed that NO emission increased with increasing NH 3 concentration. Furthermore, NO reburning results implied that with increasing NO concentration, the total NO reduction increased, whereas the reduction ratio decreased. [ABSTRACT FROM AUTHOR]

Abstract To understand the potential leaching toxicity of V in spent SCR catalysts for human and environment, the leaching behavior of V in spent V 2 O 5 -WO 3 /TiO 2 SCR catalysts before and after cement stabilization/solidification (S/S) process was investigated. The results showed that the cement mixing ratio, curing time and solidifying agents (Na2S and sodium diethyl dithiocarbamate (DDTCNa)) obviously affect the leaching ability of V in spent SCR catalysts. The leaching amount, leaching concentration and leaching rate of V in original spent SCR catalyst are 137.98 mg/kg, 13.79 mg/L and 1.82%, respectively. After the spent SCR catalyst was solidified with cement and cured for 28 days, the leaching concentrations of V in catalyst-cement solidified waste are 2.27 mg/L for 30% of cement addition and 0.14 mg/L for 70% of cement addition, respectively. Increasing cement mixing ratio and curing time could decrease the leaching concentrations of V in the cement solidified waste by affecting the generation of V5+-bearing species, which was identified by XRD, BET, SEM and FTIR. The heavy metal V could be immobilized through the formation of VO 4 3--bearing compounds in hydrating cement matrix. Evaluation on the leaching concentrations of V after adding Na 2 S and DDTCNa in cement solidified waste revealed that Na 2 S and DDTCNa are capable of reducing leaching concentrations of V from 6.25 mg/L to 5.74 mg/L and 4.65 mg/L, respectively. DDTCNa showed a better solidification performance for V compared to Na 2 S. [ABSTRACT FROM AUTHOR]

Highlights • Effect of pre-reforming by Fe/bio-char catalyst on bio-oil reforming was studied. • Fe/bio-char pre-reforming increases the H 2 and CO yields from bio-oil reforming. • Fe/bio-char catalyst promotes the transformation of aromatics into light compounds. • Less coke was formed on Ni-based catalyst due to Fe/bio-char catalyst at 550–600 °C. • Pre-reforming promotes the formation of NiO and NiAl 2 O 4 on Ni-based catalyst. Abstract Ni-based catalyst is prone to the deactivation by coke deposition during the catalytic steam reforming of bio-oil. In order to optimize catalytic activity of the Ni-based catalyst, a two-stage catalytic reforming scheme was proposed whereby a low-temperature (350–600 °C) pre-reforming process with a less expensive catalyst was introduced prior to the Ni-based catalyst. To study this scheme, the reforming experiments with different combinations of Fe/bio-char (in the first stage) and Ni-Ca/γ-Al 2 O 3 (in the second stage) were conducted. In addition to the quantification of product yields, the tar and gas were characterized with an ultraviolet (UV) fluorescence spectroscopy, a gas chromatography/mass spectrometer (GC/MS) and a gas chromatography (GC). The results indicate that significant proportions of naphthalenes and polycyclic aromatics in the intermediate volatiles turned into furans, phenols and non-aromatics, which are easier to be reformed on Ni-based catalysts, via the Fe/bio-char pre-reforming, resulting in the increase of the final H 2 and CO yields of the overall process. At high pre-reforming temperatures (550–600 °C), the coke formation on Ni-based catalyst was significantly inhibited due to the Fe/bio-char pre-reforming. In addition, the results indicate that the spent Ni-based catalyst had more free NiO and NiAl 2 O 4 spinel than the fresh one, suggesting that the increase in the catalytic activity of Ni-based catalyst during the reforming process was promoted by Fe/bio-char pre-reforming. [ABSTRACT FROM AUTHOR]

Highlights • This study focuses on the evolution of heavy component of bio-oil during pyrolysis. • Temperature and heating rate influence the evolution of heavy components obviously. • O-containing species are prone to be enriched in the heavy components. • Polymerization of heavy components and breakage of O-species are simultaneous. • Molecular weight and O numbers of heavy components are not in linear relationship. Abstract The knowledge about the formation of the heavy tars of bio-oil during pyrolysis is of great importance for the further utilization of bio-oil. This work focuses on the formation of the heavy tars during pyrolysis of bio-oil at various temperatures and heating rates in a fixed-bed reactor. In order to investigate the detailed composition of the heavy tar, the bio-oil and tars were characterized with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). Our results indicate that low temperature promotes the formation of heavy tars via the polymerization of bio-oil components, especially at slow heating rates, therein the condensed aromatics are formed via the polymerization of small aromatics with one or two rings. High temperature promotes the breakage of the oxygen-containing functional groups, meanwhile the highly condensed aromatics with more than 4 rings are formed at 800 °C via the strong secondary reactions (e.g. recombination), especially at fast heating rates. [ABSTRACT FROM AUTHOR]

Abstract Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are an important group of components produced from the thermal conversion of cellulose. Through using gas chromatography mass spectrometry (GC–MS), Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) and ultraviolet fluorescence spectroscopy (UV-F), the information for the evolution of OPAHs is obtained in this study. The tar produced at low temperature mainly contains light components such as homologues of pyran and furan, while the components in the tars at 700 °C and 900 °C show high double bond equivalent (DBE) values, indicating the existence of large aromatic structures. High temperature promote condensation reactions during cellulose thermal conversion, thus leading to a higher percentage of OPAHs in the tar at higher temperature process. According to Density Functional Theory (DFT) calculation, the energy barrier of Diels-Alder reaction (302.65 kJ/mol) is lower than the dehydration (583.26 kJ/mol), which means that Diels-Alder reaction could be the main route for OPAH formation rather than dehydration reaction. High reaction temperature is calculated to be favorable for the formation of naphthol during the cellulose thermal conversion because of the high energy barrier of dehydration between phenol and furan. It is consistent with the ESI FT-ICR MS result that there is a higher content of naphthol in the tar at 700 °C than that at 500 °C. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • KOH led to collapse of porous structure of alumina and aggregation of nickel. • KOH addition to alumina introduced abundant weak, medium and strong basic sites. • Formate intermediate formed over KOH/Al 2 O 3 , while carbonates formed over Al 2 O 3. • Formate strongly absorbed on Ni-KOH/Al 2 O 3 , leading to low activity for methanation. • Ni-KOH/Al 2 O 3 promoted CO formation in steam reforming via promoting RWGS reaction. Abstract In this study, strong basic sites were introduced into Ni/Al 2 O 3 catalysts via modification of the catalysts with the strong base like KOH. Effects of the basic sties on physiochemical properties of the catalysts and the reaction intermediates formed in methanation and reverse water gas shift reaction (RWGS) were investigated. The KOH added to the catalyst reacted with alumina, leading to the collapse of the porous structure, the decreased surface area and the aggregation of metallic nickel. The addition of KOH also introduced abundant weak, medium and strong basic sites, which helped to absorb/activate CO 2 and further converted CO 2 to CO through RWGS reaction via a formate intermediate formed. In the absence of KOH, carbonates were the main intermediates, decomposition of which to CO was relatively difficult. The in-situ DRIFTS study showed that the formate intermediates strongly absorbed on surface of Ni-KOH/Al 2 O 3 catalyst, preventing the further hydrogenation of CO intermediates to CH 4. However, the catalyst had high activity for the RWGS reaction to form CO. CO is a major by-product in steam reforming reactions. The superior activity of Ni-KOH/Al 2 O 3 for RWGS reaction contributed to CO formation when the catalyst was applied in steam reforming reactions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • H 2 O and CO 2 have a nonlinear effect on the generation of SO 3. • High concentration of H 2 O decreases SO 3 generation by inhibiting SO 2 adsorption. • High concentration of CO 2 decreases of SO 3 generation by decreasing Oα proportion on catalyst. Abstract The understanding of the generation mechanism of SO 3 on V/W/Ti catalysts provides needed information for the achievement of ultra-low emission of pollutants and effective control of SO 3 generation. This study predominantly investigates the catalytic oxidation mechanism of V/W/Ti catalysts for SO 3 generation under H 2 O and CO 2 conditions. Ion Chromatography (IC), X-ray Fluorescence (XRF), Brunauer–Emmett–Teller (BET) specific surface area, Scanning Electron Microscopy image (SEM), Energy Dispersive X-ray (EDX), SO 2 Temperature-Programmed Desorption (SO 2 -TPD), X-ray Photoelectron Spectroscopy (XPS) experiments, and Fourier Transform Infrared spectroscopy (FT-IR) were used to characterize catalyst properties and the catalytic oxidation generation mechanism of SO 3. Results show that Catalyst V content was more influential than physical property on the generation of SO 3. In this study, when H 2 O or CO 2 was added into the reaction atmosphere, the generation amount of SO 3 would increase firstly, and then gradually decrease with the further increase of H 2 O or CO 2 concentration. Through further mechanistic analysis, it was found that the influence mechanism of H 2 O and CO 2 on the generation of SO 3 was different. Various kinds of intermediate species such as [OH] and HOSO 2 were introduced by the addition of H 2 O, resulting in the increase of lattice oxygen (Oα) proportion and SO 3 generation path. However, the inhibition effects of high concentration of H 2 O on SO 2 adsorption and sulfur oxides migration were the main reason for the decrease of SO 3 generation under high H 2 O containing conditions. Conversely, although the adsorption SO 2 was promoted by CO 2 , high CO 2 addition leads to the apparently reduction of Oα proportion on catalyst resulting in the decrease of SO 3 generation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Furan can be converted to methyl levulinate in dimethoxymethane. • 2-methoxymethylfuran is an intermediate formed via electrophilic substitution. • Methanol in reaction medium suppresses the polymerisation to some extent. • Dimethoxymethane can react with methyl levulinate, which is a key side reaction. • DRIFTS study shows structures of coke from furan or methyl levulinate is different. Abstract This study developed a method for the direct conversion of the biomass-derived furan to the methyl levulinate, a platform molecule, via acid-catalysis in dimethoxymethane/methanol. Dimethoxymethane acted as the electrophile to transform furan into 2-methoxymethyl-furan (the ether of furfuryl alcohol). The following step of acid catalysis converted 2-methoxymethyl-furan to methyl levulinate. No hydrogenation catalyst or hydrogen was used in the process, which was the new reaction route for the conversion of furan to the value-added levulinic acid/ester. Polymerization was the main challenge in this reaction route, which could be suppressed but to some limited extent with methanol as a co-reactant/solvent in the reaction medium. The polymerization of furan and cross-polymerization reactions between dimethoxymethane (the reactant) and methyl levulinate (the targeting product) via Aldol condensation were the important reasons for the decreased production of methyl levulinate. The DRIFTS and TG-MS studies showed that the coke formed from the polymerization of furan contained more aliphatic structure, more carboxylic groups and methyl groups, while the coke from methyl levulinate contained more carbonyl groups and more conjugated π-bonds, projecting the structural difference of furan and methyl levulinate. [ABSTRACT FROM AUTHOR]

This study focuses on the effects of interactions among bio-oil components on the formation of aromatic structures of bio-oil during its thermal treatment processes at various temperatures and heating rates. A bio-oil sample and its extracted fractions were pyrolyzed in a fixed-bed reactor at 300–800 °C at different temperatures and heating rates. The results show that the pyrolytic products (including the yields and aromatic structures) from raw bio-oil and its extracted fractions are significantly different, which proves the existence of the interactions between the aromatic components and light components of the bio-oil. Additionally, those interactions are determined by the pyrolysis temperature and heating rate to different extents, which further leads to the evolution of aromatic structures during the pyrolysis of bio-oil. For example, owing to the presence of the aromatic-poor fraction, the aromatic compounds (especially ≥ 2 rings) from the pyrolysis of bio-oil are less than that of the aromatic-rich fraction at relatively low temperatures (≤ 500 °C), especially at slow heating rates. This is because the polymerization, as the main interactions, promotes the transformation of more aromatic compounds (over wide range of ring sizes) into coke at these conditions. At fast heating rates, among the complex interactions, the self-gasification of bio-oil is intensified at high temperatures (≥ 700 °C), resulting in lower secondary coke yields and tar yields as well as the concentration of aromatic compounds (especially ≥ 2 rings). [ABSTRACT FROM AUTHOR]

[Display omitted] • The evolution of nitrogen in pyrolysis oil and pyrolysis gas during the pyrolysis of food waste was investigated. • NH 3 mainly comes from the detachment of amino groups. • HCN is mainly derived from the dehydrogenation of amino acids and the cleavage of N -containing heterocycles and nitriles. • N -containing heterocycles are the main N -containing substance in pyrolysis oil. • N -containing heterocycles are generated by de-H 2 O or intermolecular de-H 2 O of amino acids or condensation reactions of amino acids with small molecules. Pyrolysis technology is an effective way to realize the reduction and recycling of food waste (FW), but the generation of N -containing substances has a great impact on the quality of pyrolysis products and the environment. The present study mainly focused on the migration and transformation mechanism of N during the pyrolysis process of FW, which was investigated by TG-FTIR, GC–MS, and DFT calculation. The experimental results show that NH 3 and HCN are the main N -containing gas products, and the N -containing substances in the pyrolysis oil are mainly N -containing heterocycles (21.82%), nitriles (6.43%), and amides (4.00%) at 500 ℃. The proteins in food waste are cleaved into various amino acid molecules at temperatures above 300 ℃. Some amino acid molecules generate NH 3 and HCN by removing various groups. Some other amino acid molecules generate N -containing heterocycles, nitriles, amides, and various other N -containing substances by intramolecular de-H 2 O or intermolecular de-H 2 O reactions of amino acids or condensation reactions of amino acids with small molecules and transfer to the pyrolysis oil. As the temperature increases, most of the N -containing heterocycles and nitriles will be cleaved and generate HCN. [ABSTRACT FROM AUTHOR]

A series of Mn x O y /Al 2 O 3 sorbents with different tissue and chemical structures were prepared by repeated incipient wet impregnation method with different calcination conditions, including calcination temperature from 500 °C to 900 °C and calcination time from 3 h to 9 h. The H 2 S absorption performances of the prepared sorbents were investigated by a model synthesis gas containing 2000 mg/m 3 H 2 S at 850 °C. The chemical and physical structures of the samples were characterized by Brunauer–Emmett–Teller, X-ray diffraction and scanning electron microscopy techniques to obtain fundamental information about the deactivation of Mn x O y /Al 2 O 3 sorbents during desulfurization–regeneration cycles. Results showed that the structural features of the sorbents at high reaction temperature played an important role in the stability of desulfurization performance. The analysis of the characteristics of the sorbents indicated that the sorbents obtained stabilized chemical and physical structures during desulfurization–regeneration cycles when the calcination temperature was 900 °C and the calcination time was above 6 h. The sorbent suffered serious deactivation during five successive desulfurization–regeneration cycles when the calcination temperature of sorbents was below 850 °C. The sulfur capacity decreasing of Mn x O y /Al 2 O 3 sorbents may probably be attributed to a part of Mn x O y covered by Al 2 O 3 , which can un-sulfide during adsorption process. The coverage of active phase Mn x O y may be caused by the shrinking and disappearing of some micropores, and phase transformation of Al 2 O 3 , as well as the transformation of MnAl 2 O 4 lead to a part of Mn x O y on the sorbents being covered by alumina. [ABSTRACT FROM AUTHOR]

In this study, steam reforming of acetic acid over the Ni/γ-Al 2 O 3 catalysts with varied nickel contents (from 2.5 to 40 wt%) was performed, aiming to investigate the effects of nickel loading on properties and catalytic behaviors of the catalysts. The results show that the interaction of nickel species with alumina varies with varied nickel loading. At lower nickel loadings, the nickel strongly interacting with alumina are the main species, while with the saturation of the reactive sites of alumina via loading more nickel, the proportion of the nickel species weakly interacting with alumina increased remarkably. Excess nickel on alumina can fill the pores, decreasing the reduction degree of nickel oxides, the specific area (from ca. 277 to 132 m 2  g −1 with the increase of nickel loading to 40 wt%), the pore volume, and the pore diameters. Nickel loading also significantly affects the catalytic activity, stability of the catalyst and the resistivity towards coking. With the increase of nickel loading to 10 wt%, the activity of the catalyst reached a plateau. The further increase of nickel loading did not further increase the activity, but increased the stability and the tolerance towards the deactivation induced by coking. In addition, with higher nickel loadings, the coke formed has more large aromatic ring system. [ABSTRACT FROM AUTHOR]

Four types of biomass-derived organics (toluene/1-methylnaphthalene/phenol/ethanol) were catalytically decomposed and steam reformed over Ni/α-Al 2 O 3 for co-production of hydrogen and carbon nanotubes (CNTs). In the decomposition reaction, the oxygen functional group in phenol and ethanol promoted the co-production of hydrogen and CNTs, while a small amount of toluene and 1-methylnaphthalene were cracked to hydrogen and amorphous carbon. In the reforming reaction, the yields of hydrogen and CNTs sharply increased. More than 2000 mmol/(g-cata∗h) of H 2 and 260 mg/(g-cata∗h) of CNTs were produced after the reforming of toluene and ethanol. However, 1-methylnaphthalene was difficult to be reformed and small amount of CNTs were formed. The organics with low molecular weight and low degree of unsaturation conduced to the formation of hydrogen and CNTs. The growth of CNTs on Ni/α-Al 2 O 3 mainly follows the tip-growth mechanism. The diameter distribution of CNTs is not only influenced by Ni particle size, but also related to the different organics and steam addition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon nanotubes (CNTs) with tip-growth mechanism were generated at 600 °C. • More amorphous carbon and carbon nanofibers (CNFs) were formed at 700 °C. • H 2 yield exhibited the "N" type trend as temperature increasing from 500 °C to 800 °C. • H 2 yield at 600 °C was higher than that at 700 °C due to the self-activation of CNTs. • Self-assembled CNTs@Ni foam at 600 °C performed best electrochemical performance. The H 2 production and self-assembly CNTs over Ni-Fe/Ni foam catalyst were investigated at different temperatures during steam reforming of bio-oil model compound. The formation of CNTs, CNFs and amorphous carbon and their different effects on catalytic activity were analyzed. With the temperature increasing from 500 °C to 800 °C, the amount of carbon deposition firstly increased and then decreased. It showed the highest amount of carbon deposition and largest proportion of CNTs (over 60 %) at 600 °C. The average diameter of CNTs was 15.18 nm. By contrast, more than 70 % of carbon deposition was amorphous carbon, and the CNFs with larger diameter (over 100 nm) were formed at 700 °C, which attributed to the agglomeration of metal particles at high temperature. The high reaction temperatures increased H 2 yield and pyrrole conversion, but differently, those at 600 °C was remarkably higher than that at 700 °C. It revealed that tip-growth of CNTs at 600 °C performed the self-activation effect to increase the catalytic activity, while the amorphous carbon generated at 700 °C deactivated the catalyst. After the reaction at 600 °C, the self-assemble of CNTs@Ni foam material showed the highest electrochemistry performance. [ABSTRACT FROM AUTHOR]

• Interaction between the sewage sludge and coal slime during their co-combustion was found. • SO 2 formation and release mechanism during co-combustion of sewage sludge and coal slime was revealed. • AAEMs play a key role on the evolution of S-functional groups. The production of sewage sludge (SS) and coal slime (CS) is increasing year by year, which affects the ecological environment and human daily life, and it is urgent to deal with them reasonably. This study investigated the SO 2 release characteristics and the evolution of S functional groups and minerals during the combustion of SS, CS and their blends. The results showed that the co-combustion of SS and CS had an interaction on desulfurization. When the temperature was 800 ℃ and the blend ratio of SS was 20%, it was most beneficial to suppress the emission of SO 2. The types of S functional groups in SS and CS were similar but the relative content was different. The evolution of some S functional groups showed various laws. In the early stage of co-combustion, Sulfate (S1) reached maximum value earlier and decreased at the end of co-combustion, and Sulfide (S5) were more likely to be converted to aromatic-S (S4). According to XRD and SEM-EDS results, Ca (mainly CaCO 3) in the fuels had a significant effect on SO 2 release characteristics during the co-combustion. CaO formed by thermal decomposition of CaCO 3 could react with SO 2 to form intermediate solid products (CaS and CaSO 3). These intermediates further reacted with O 2 to generate CaSO 4 , thus retaining SO 2 in the ash. Some CaSO 4 was decomposed in the later stage of combustion, leading the re-release of SO 2. Excessive combustion temperature and reductive gases would lead to the decomposition of CaSO 4 , which reduced the ability of Ca to absorb SO 2. [ABSTRACT FROM AUTHOR]

The behaviour of mercury is investigated in a 35 MW th large pilot boiler of oxyfuel combustion with dry and wet flue gas recycle (FGR). The mercury species in fly ash particles as well as the involved reaction mechanism are systematically investigated. The results suggest that higher concentration of gas–phase mercury (Hg g ) is contained in oxyfuel combustion flue gas. The conversion of Hg g to particulate associated mercury (Hg p ) is enhanced in oxyfuel combustion. Different mercury species are presented in fly ash collected from air and oxyfuel combustion: trigonal red HgS is the main mercury species in air combustion; mercury bound to organic matter (Hg–OM) and trigonal red HgS are both dominant in the samples from oxyfuel combustion. The prominent difference is the significantly increase of Hg–OM in oxyfuel combustion atmosphere. The oxyfuel combustion atmosphere would favor the formation of oxygen–rich functional groups, especially the C O group, which is responsible for the adsorption of mercury and formation of Hg–OM in fly ash. [ABSTRACT FROM AUTHOR]

The existence form and structure properties of mobile phase (MP) in low-rank coals (LRCs) can significantly influence the initial stage of thermal conversion. In the present work, three Chinese LRCs, namely, Shenfu, Zhundong and Hongshaquan, were extracted with tetrahydrofuran using the microwave-assisted heating. The tetrahydrofuran-microwave-extracted (TME) portion as the representative of MP was further separated to four fractions defined as oil, resin, asphaltene and preasphaltene, respectively. Diffuse reflectance Fourier transform-infrared spectroscopy (DRIFT), gas chromatography/mass spectrometer (GC/MS), matrix-assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOF-MS) and X-ray photoelectron spectroscopy (XPS) were used to comprehensively investigate the molecular characteristics of the derived materials. The results indicated that the studied TME portions were mainly consisted of asphaltenes and rich in highly branched aliphatic hydrocarbons due to the relatively low CH 2 /CH 3 and H ar /H al ratios. Para -alkyl substituted aromatic structures with 1–2 rings were the main aromatic structures in the TME portions. C O bonds were the main oxygen-containing structures in the TME portions and could be more likely seen in aliphatic compounds. Combining the MALDI-TOF-MS and DRIFT analyses, the ratio of aliphatic side chains and aromatic hydrogens (3000–2800 cm −1 /900–700 cm −1 , I 2 ) derived from IR spectra seemed to be a suitable parameter for assessing the average molecular weight (AMW) of the specific fraction in TME portion of LRCs when the ratio of C O/C O was at very low level. The results made a further explanation for the detailed chemical structure of mobile phase in coal and could be helpful for studying the formation mechanism of volatiles during pyrolysis process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-pyrolysis was performed in a photothermal TG system under high heating rates. • Activation energy relative difference was used to quantify the synergistic effect. • Thermo-kinetic properties were significantly affected by high heating rates. The heating rate would significantly impact the pyrolysis process, especially for the reactions containing synergistic effects between two different feedstocks. Co-pyrolysis of two widely available biomass (CC–corncob and PS–peanut shell) with plastic (PET–polyethylene terephthalate and PVC–polyvinyl chloride) was studied in a concentrating photothermal thermogravimetric analysis (CP-TGA) system at three heating rates (100, 500, 1000℃/min). The TG and DTG curves of CC and PS differ due to their polymeric components (holocellulose and lignin); two pronounced levels at 100 and 500 ℃/min heating rates were present in PVC. With increasing heating rate, the lateral shift towards higher temperature regions in the TG and DTG curves exceeded 100 °C. The synergistic effects on the blend samples were concentrated in the main decomposition region (250–580℃) due to rapid volatiles release, and the discrepancy values further stabilized at the final decomposition stages. The activation energy (Ea) was assessed using a comparative study of isoconversional methods, namely Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Starink. The isoconversional methods demonstrated that the co-pyrolysis process required about 30 % less activation energy than the pyrolysis of plastic (PET/PVC) alone. Coats-Redfern's (CR) model-fitting approach was used to identify the kinetic triplet of the devolatilization stage. The CR models revealed that biomass–PET blends belong to two to four-dimensional diffusion models, whereas biomass–PVC blends are dominated by chemical reactions of 1.5 and 2 orders. The energy barrier between activation energy (Ea) and change in enthalpy (ΔH) for all the blend samples was lower (∼5–6 kJmol−1), which slightly increased at higher heating rate. [ABSTRACT FROM AUTHOR]

• A novel photothermal pyrolysis system was successfully built to treat waste tire. • High-yield limonene can be acquired with the photothermal pyrolysis of waste tire. • Waste tire photothermal pyrolysis and limonene generation mechanisms were found. Waste tire is a typical solid municipal waste with large production capacity. Developing new low carbon-emission method to pyrolyze waste tire and produce high-value limonene is promising. Herein, a novel photothermal pyrolysis system was successfully built, and waste tire was firstly pyrolyzed by photothermal at different temperatures (400 °C, 500 °C, 600 °C, and 700 °C). The photothermal pyrolysis can assist in achieving high yield of limonene, of which the yield can high up to 8.98 wt% at 600 °C and the relative peak areas of Gas Chromatography-Mass Spectrometer (GC–MS) results were all about 30 A.%. cis-1,4-polyisoprene in waste tire partly decomposed into some free radicals and they further reacted to generate limonene by intramolecular cyclization, dimerization, and isomerization. Parts of limonene aromatized to 1-methyl-4-(1-methylethenyl)-benzene and converted to triolefins that formed diene rings, the diene rings further aromatized to xylene and toluene, which were partly combined to generate 1,6,7-trimethyl-naphtalene. The photothermal pyrolysis mechanisms of waste tire were revealed: At higher pyrolysis temperature, waste tire partly decomposed and others polymerized to form amorphous carbons. The small aromatic rings and alkyl-aryl C C bonds further polymerized to be large aromatic rings system. The pores in char further formed and limonene generation was strengthened, because the limonene formation/decomposition was mainly limited in the pores. Subsequently, some pores were blocked at 700 °C, the generation of limonene was thus inhibited. [ABSTRACT FROM AUTHOR]

[Display omitted] • Double-green of purifying electroplating Ni wastewater and producing H 2 was realized. • Surface complexation and ions exchange mechanisms of biochar promoted Ni2+ removal. • The recycled Ni on biochar increased the H 2 yield by 15 times. • Two-step activation of steam and H 2 greatly improved double-green performance. • Steam activation increased surface area, Ni dispersion and surface Ni amount. The new method of using biochar to purify nickel-simulated electroplating wastewater and subsequent preparation of a Ni-based catalyst to produce H 2 in bio-oil reforming reaction is proposed. This process aims to realize the double-green of wastewater treatment and H 2 production. Different types of biochar (rice straw, rice husk and cotton stalk) were used. The results indicated that rice straw char (RSC) performed the highest Ni2+ removal efficiency due to ash components' high ion exchange capacity and high complexation ability of oxygen-containing functional groups. Then the adsorbed RSC was reduced and recycled to prepare Ni/RSC catalyst. Compared with the unadsorbed RSC, the recycled metal Ni remarkably improved the catalytic activity. The average carbon conversion of acetic acid at 600 °C was increased to 76.26% and H 2 yield was increased by 15 times. To further enhance the double-green performance, a two-step activation process was implemented. The biochar was firstly corroded by steam addition (5%, 15% and 25%) and then the adsorbed biochar was reduced by H 2. After that, the surface area, oxygen-containing functional groups and exchangeable cations of biochar were remarkably enhanced, which increased the Ni removal efficiency to reach 100%. Besides, the formed metal Ni with the higher metal dispersion and smaller Ni particle size improved the reforming of acetic acid. The activation by adding 25% steam further improved carbon conversion by 13.34% and H 2 yield by 60.47%. [ABSTRACT FROM AUTHOR]

[Display omitted] • The MnFeW/Ti catalyst exhibited high activity for simultaneous removal of NO and Hg0. • NO significantly enhanced the catalytic activity for Hg0 oxidation in the presence of O 2. • NH 3 did not affect the Hg0 removal over MnFeW/Ti catalyst. • HgO, resulted from the reaction of NO 2 and Hg0, is liable to desorb. The MnFeW/Ti catalyst was synthesized and used for simultaneously removing NO and Hg0 from flue gas at low temperature and its catalytic performance has been tested. The MnFeW/Ti catalyst showed over 80% NO x conversion and 88% Hg0 removal between 180 and 300 °C at a high GHSV of 100000 h−1. NO obviously enhanced the catalytic capability for Hg0 removal and NH 3 had almost no effect on Hg0 removal because NH 3 did not affect the adsorption of NO and Hg0. Hg balance results revealed that Hg0 removal over MnFeW/Ti catalyst proceeded via both chemisorption and catalytic oxidation, which is attributed to the different bonding strength between Hg0 and active sites. The Hg0 oxidation process was also investigated through transient reaction experiments along with Hg-TPD and XPS characterization. Hg0 oxidation over MnFeW/Ti catalyst obeys both Mars–Maessen mechanism in which active oxygen reacts with adsorbed Hg0 and Langmuir − Hinshelwood mechanism comprising the reaction of formed NO 2 with adsorbed Hg0. HgO, resulted from the reaction between NO 2 as an active intermediate and adsorbed Hg0, is liable to desorb from MnFeW/Ti catalyst. [ABSTRACT FROM AUTHOR]

• Char structure was investigated via characterization of its extraction and residue. • Effects of pellet sizes on char structure were weakened by temperatures. • Polymerisation of extract is account for the structural difference of pellet chars. • Aromatisation degree of pellet char is related to its surface-area-to-volume ratio. Char structure can reflect the pyrolysis characteristics and affect the efficiency of gasification and combustion processes, while biomass pellet size and shape are critical for the heat and mass transfer, which in turn influence greatly char structure. The aim of this study is to experimentally study and compare the effect of aspect ratio (diameter/length) on char structure during the pyrolysis of sawdust pellet. Cylindrical sawdust pellets with similar masses and volumes but different diameters (6, 8, 12, 16 mm) were pyrolysed at various temperatures. The chars were separated into two phases (liquid extraction, solid residue) via microwave-assisted extraction. Experimental results show that the pellet with a low aspect ratio had a large char yield because of intra-particle volatile-char interaction especially at low temperature, while there was an optimum aspect ratio due to the change of residence time. The pellet with a high aspect ratio had an intense polymerisation, resulting in the formation of fused aromatic rings in char and residue. By increasing aspect ratio, there was a lowest surface area. This means that less heat entered from surface, and low thermal conductivity caused a slow decomposition. Due to large heat and mass transfer residence, more aromatic molecules with small weight formed in extracts of char, especially at high temperature. Besides, an increase in temperature weakened the differences in structural features of the pellet char caused by different aspect ratios. [ABSTRACT FROM AUTHOR]

[Display omitted] • The deposition and transformation of ammonium bisulfate (ABS) on fly ash under variable temperature conditions was investigated. • Fly ash enhanced ABS deposition by trapping and absorbing effects. • ABS deposition is positively correlated with the product of SO 3 and NH 3. • Along the flow direction of flue gas in the air preheater, the deposited products will gradually convert from ABS to the mixture of ABS and H 2 SO 4. • ABS will convert into sulfate with higher decomposition temperature on fly ash. Ammonium bisulfate (ABS) aggravates the corrosion and plugging of air preheaters, resulting in unplanned outages and expensive cleaning. Understanding its deposition and transformation process is important for the development of ABS control strategies. A multistage temperature control system was built to simulate the temperature gradient in the air preheater and the deposition and transformation of ABS in the presence of fly ash were studied using Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetry. The presence of fly ash increases both the deposition amount and the temperature of ABS in the 25–200 ppm SO 3 concentration range; the initial ABS deposition temperature is between 202 and 290 ℃ and most likely occurs in the 230–250 ℃ range. The main product was ABS, and its formation temperature was much higher than the deposition temperature observed in the experiment. In the 224–180 ℃ range, the products gradually changed from ABS to sulfuric droplets. Fly ash has trapping and adsorbing effects on the gas-phase ABS in flue gas, and more ABS is captured at high temperatures owing to the higher concentrations of reactants. ABS deposition leads to the accumulation and adhesion of fly ash particles and reacts with the fly ash to convert it into a variety of ammonium salts and sulfates with higher decomposition temperatures. Compared with the sulfate formed after the deposition of sulfuric acid droplets, the sulfate formed by ABS conversion had a lower relative decomposition temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of minerals in sewage sludge (SS) on coal slime (CS) combustion were studied. • The minerals in SS are the main factor for the interactions between CS and SS. • Fe 2 O 3 exhibits the best catalytic effect for CS-fixed carbon among single minerals. • Fe 2 O 3 and CaO synergistically catalyzed CS combustion. • Fe 2 O 3 reacted with Fe 3 (PO 4) 2 to form the dense products that inhibit the burnout. The co-combustion of sewage sludge (SS) and coal slime (CS) is a promising approach to realize the harmless disposal of these two solid wastes. Aiming at the effects of the minerals in SS on CS combustion during the co-combustion, the combustion characteristics and kinetics of CS under the action of CaO, Fe 2 O 3 , and Fe 3 (PO 4) 2 were investigated by a thermogravimetric analyzer. The effects of the single and the composite minerals on CS combustion were quantified, and the synergistic or inhibitory effects between the minerals were also analyzed. Furthermore, Flynn-Wall-Ozawa (FWO) method and the master plots method were used to calculate the combustion kinetics. The results revealed that the catalysis of the minerals in SS was an important factor for the interaction between SS and CS during the co-combustion. For the single minerals, Fe 2 O 3 exhibited the best catalytic effect, which reduced the ignition temperature (T i) and burnout temperature (T b) by 8.2 °C and 42.2 °C, respectively, and increased the comprehensive combustion characteristic index (S) by 10.7%. For the composite minerals, Fe 2 O 3 and CaO synergistically catalyzed CS combustion through a cascade chain catalytic mechanism, resulting in a 15.9% increase in S compared with CS combustion alone. However, the interaction between Fe 2 O 3 and Fe 3 (PO 4) 2 at high temperatures produced dense products that inhibit the burnout process. The kinetic results showed that the minerals in SS led to a decrease in the apparent activation energy of CS during the combustion stage of the fixed carbon, and the order of decreasing degree was Fe 2 O 3 + CaO > Fe 2 O 3 > Fe 2 O 3 + CaO + Fe 3 (PO 4) 2. In addition, the combustion of CS was a multi-step kinetic process, and the mechanism function changed from f(α)= (1-α)4 to f(α)= (1-α) as the combustion progressed. The composite mineral Fe 2 O 3 + CaO participated in the combustion reaction of fixed carbon in CS, changing the reaction mechanism from F1 to F1.3. [ABSTRACT FROM AUTHOR]

• A concentrating photothermal TGA with wide range heating rate was developed. • The maximum mass loss rate of coal pyrolysis increased linearly with heating rate. • The mean activation energy decreased exponentially with the increase of heating rate. • The transformation rates of functional groups were accelerated with the heating rate. • The activation energy was binomially correlated with the I (Gr+Vl+Vr) /I D. Coal pyrolysis is the initial reaction of vast utilization technologies, and the quantitative description of pyrolysis characteristics and accurate kinetic parameters under the wide range of heating rates are of significant challenges. The effect of heating rate from 5 ℃/min to 1000 ℃/min on coal pyrolysis in a novel concentrating photothermal thermogravimetric analyzer was systematically investigated. A new temperature control scheme especially for the ultra-fast heating process was proposed, guaranteeing the absolute temperature control error was less than 4 ℃ throughout the whole heating process. As the heating rate increased from 5 ℃/min to 1000 ℃/min, the absolute value of maximum mass loss rate increased linearly from 4.18 wt%/min to 66.06 wt%/min, and the specific reaction rate for coal conversion at 20% and 50% also increased linearly by 15.4 times and 16.4 times, respectively. The mean activation energies exhibited the exponential decrease tendency from 235.41 kJ/mol to 28.37 kJ/mol. The transformation rates for functional groups of chars were accelerated with the heating rate, and the char with same conversion rate would be more condensed. The activation energy of coal during pyrolysis under heating rate of 1000 ℃/min was binomially correlated with the ratio of small aromatic rings to large ones in char. [ABSTRACT FROM AUTHOR]

• The evolution of heavy volatile during cellulose steam reforming was revealed. • Heavy components were formed by polymerization accompanied with deoxygenation. • Steam simultaneously accelerated cracking and polymerization of heavy components. • KCl facilitated the generation of heavy phenols below 700℃. • Molecules below 300 Da significantly increased in the presence of KCl. Biomass sources could transform into green chemicals and energy through steam reforming but heavy components of the resulting volatile, which are the precursors of undesirable coke, would also be formed. In the current study, the evolution of heavy components from cellulose is investigated. The effects of an inorganic potassium salt KCl on the heavy component evolution during steam reforming are firstly revealed in the homogeneous steam-volatile reforming process. The results suggest that heavy components were formed by polymerization reactions accompanied with dehydration and decarboxylation. Steam and alkali metal both promoted the cracking and secondary polymerization of heavy components. In the presence of steam and alkali metal, the percentage of molecules with low weight (<250 Da) and high weight (>500 Da) both improved. KCl significantly promoted the polymerization of oxygen-containing compounds, increasing the average oxygen number of the heavy components by 1.4 to 2.2 times depending on the reaction temperatures. Heavy phenols are also promoted in the presence of alkali metal below 700℃. [ABSTRACT FROM AUTHOR]

A series of novel magnetic Cu 0.3 Fe 2.7− x Ti x O 4 composites was synthesized and used as recyclable heterogeneous Fenton-like catalysts for gaseous elemental mercury (Hg 0 ) removal from simulated flue gases. The technique of inductively coupled plasma-atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM), and X-ray photoelectron spectrometry (XPS) were used, and Brunauer Emmett Teller (BET) analysis was achieved to determine the chemical composition, pore structure, and surface chemistry of the catalysts. The performance of heterogeneous Fenton-like reactions for Hg 0 removal was investigated in a bench-scale bubbling reactor under neutral condition. Some main parameters such as Cu/Ti ratio in the catalysts, H 2 O 2 concentration, solution pH, and gas flow were systematically studied to establish optimal reaction conditions. The effects of SO 2 and NO on Hg 0 removal were also analyzed. Vibrating sample magnetometer (VSM) analysis suggested the Cu 0.3 Fe 2.7− x Ti x O 4 catalysts can be manipulated by an external magnetic field, and have potential advantages in terms of separation and recovery. Hg 0 removal remained efficient after five repeated experiments with only a slight decrease. Electron spin resonance (ESR) was applied to confirm the active hydroxyl radical ( OH) generated during heterogeneous Fenton-like reactions. [ABSTRACT FROM AUTHOR]

• Inorganic sodium inhibits coal combustion in early stage under fast-heating rate. • Ignition delay time of NaCl-loaded coal increases visibly under fast-heating rate. • Evolution pathways of condensation reactions catalyzed by Na are studied by DFT. • Na in studied coal reduces energy barrier of condensation reactions in early stage. The combustion characteristics of raw (RAW), acid-washed (AW) and inorganic sodium impregnated (NaCl-loaded) Zhundong (ZD) coals were researched in a fast-heating rate combustion system and thermal gravimetric (TG) analyzer, aiming to exhibit the effect of inorganic sodium on coal combustion processes under different heating rates. The results showed that the ignition delay time decreased in the order: NaCl-loaded coal > AW coal > RAW coal in the early stage with fast-heating rate. The surface temperature of NaCl-loaded coal increased the slowest, while with the highest T is , reflecting that the ignition and combustion behavior became more difficult after adding NaCl in the early stage. However, in the later stage, the fastest increase in temperature and the shortest t b , together with the shorter extinction time of volatile flame, were observed on NaCl-loaded coal. The size of NaCl-loaded coal decreased faster than that of AW coal. Thus, it can be concluded that inorganic sodium will inhibit coal combustion in the early stage, while promotes coal combustion in the later stage under fast-heating rate. In the TG experiment, the T i-TG and T b-TG of NaCl-loaded coal were lower than that of AW coal, and the T m-TG of NaCl-loaded coal moved to the low temperature area, revealing that inorganic sodium can promote coal combustion with low-heating rate during the whole combustion process. The quantum chemistry calculation at M06-2X/6-31G(d,p)//CBS-QB3 level reveals that inorganic sodium can catalyze the addition and cyclization reactions of small chain molecules in the early stage with fast-heating rate, thereby inhibiting coal combustion in the early stage, which was different from that in the later stage. Inorganic sodium will promote the formation of OH radical, and the organic sodium obtained from sodium-containing surface compounds of the char can be beneficial for the oxidation reaction of the carbon residue, thereby promoting coal combustion in the later stage with fast-heating rate, which was consistent with the references. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coke formation during bio-oil pyrolysis was inhibited via Ni/Al 2 O 3 mixing. • Influence of Ni/Al 2 O 3 mixing on aromatic structures of products was investigated. • Interaction among AF, LDO and Ni/Al 2 O 3 during bio-oil pyrolysis was revealed. • Mechanism for bio-oil pyrolysis with Ni/Al 2 O 3 mixing was proposed. Bio-oil can be converted to chemicals, carbon material, or syngas by various thermochemical processes which are always preceded with the pyrolysis step. In bio-oil pyrolysis, coke formation is almost inevitable, causing difficulties for further processing. In this study, bio-oil was mixed with Ni/Al 2 O 3 before it was fed for pyrolysis. Interesting results were observed whereby the effect of Ni/Al 2 O 3 mixing on coke formation shifted from promoting to inhibiting with increasing pyrolysis temperature. When the temperature was higher than 700 °C, contrary to the cases without mixing, the apparent decreases in coke yield were observed (e.g., the coke yield decreased by 10% at 800 °C). Comparative studies on bio-oil and its lignin-derived oligomer fraction indicated that the catalytic cracking of small molecules could enhance the formation of hydrogen radicals, which promoted thermal decomposition of lignin-derived oligomers, thus inhibiting coke formation via polymerization. [ABSTRACT FROM AUTHOR]