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The plane exposure of support vitally affects the catalytic performance of the catalyst. In this work, CeO2 nanorods ((1 1 0) plane exposure), nano-octahedrons ((1 1 1) plane exposure) and nano-cubes ((1 0 0) plane exposure) were prepared as the supports of Pt/CeO2 samples to investigate the effect of CeO2 plane exposure on total toluene oxidation. Characterizations reveal that the (1 1 0) plane of CeO2 is more helpful to the dispersion of Pt species, followed by (1 1 1) face. The improved dispersion of Pt species can enhance the metal-supports interaction, which promotes the electron transfer of CeO2 carrier to Pt nanoparticles and the adsorption-activation of O2, thereby facilitating the total oxidation of toluene via the Langmuir–Hinshelwood (L-H) mechanism. Therefore, Pt/CeO2-r (nanorods) sample expresses the most excellent catalytic performance of toluene oxidation. Finally, the procedure of toluene total oxidation was studied by in-situ DRIFT. We expect that this work can contribute to the development of an effective sample for the decomposition of volatile organic compounds (VOCs).

Polyoxymethylene dimethyl ether (PODEn, n ≥ 1) is a class of oxygenated fuels containing unique carbon-oxygen chain structure and a promising alternative fuel for diesel engines. In this study, low-temperature oxidation characteristics of PODE3 were studied experimentally and numerically. Experiments were performed in a jet-stirred reactor (JSR) at equivalence ratios of 0.5, 1.0 and 2.0, in the temperature range of 500 to 950 K, and at atmospheric pressure. Mole fractions of PODE3, O2, H2, CO, CO2, CH3OH and C1-C2 hydrocarbons were measured by gas chromatograph (GC). Experimental measurements were compared with the simulation results based on two literature low-temperature oxidation models, denoted as the He model and the Cai model, respectively. Good agreement was obtained between the measured and simulated fuel consumption profiles, while a deviation was observed between the experimental and simulation results on the mole fractions of O2 and intermediate products at medium temperatures. Reaction pathway analyses based on the two models were performed, revealing that the second O2-addition reaction pathway is more significant in the prediction by the Cai model than that by the He model. Sensitivity analyses pointed out that the most important reactions affecting fuel consumption are the H-abstraction reactions of PODE3, and the decomposition of H2O2 and the consumption of CH2O become more sensitive at medium temperatures.

No consensus has been reached on the role of reducible and irreducible supports on the reaction pathway of CO oxidation over supported metal catalysts. Here, colloidal ligand-free Pt nanoparticles were deposited on Al2O3 and CeO2 to investigate the support effect in CO oxidation by in situ diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS) and mass spectrometry (MS). On Pt/Al2O3, the carbonate-like intermediates accumulate and do not decompose to CO2 at the ignition temperature (150 °C) or above; the conversion of CO to CO2 follows classic Langmuir−Hinshelwood (L–H) mechanism with direct reaction of CO and O2 on Pt. Whereas for Pt/CeO2, the CO conversion to bidentate carbonate (b-CO32−) species followed by decomposition to CO2 is a main reaction pathway leading to its high reactivity at low temperature (75 °C). CeO2 facilitates the activation of oxygen to produce the carbonate-like intermediates and further decomposition to CO2, which resulted in a lower ignition temperature.

The fast decomposition of peroxides (M2O2, where M = H+, Li+) at room temperature has gained increased attention given its relevance, from propulsive systems to metal-O2 conversion batteries. This study describes, by a rational design of experiment, the influence of selected parameters such as: pH, initial concentration of K2CO3, precipitate aging, precipitate washing, and thermal treatment for the hydrotalcite co-precipitation, characterizing it for each synthesis variable. The results show that hydrotalcites can efficiently be converted in Co-Mn-Al spinels and as a result, a new highly active Co2Mn0.5Al0.5O4 spinel oxide was synthesized after thermal treatment. Its activity and mechanical resistance were tested in a micro-thruster reactor where it showed total decomposition (> 98%) of H2O2 and in a Li-O2 battery, with increased cyclability, been able to reduce the charging potential in ~200 mV. These encouraging results enhance the importance not only of this class of material, but also, the importance of robust synthesis methodologies for reproducible results.

The cognition of active sites in the Ni-based catalysts plays a vital role and remains a huge challenge in improving catalytic performance of low temperature CO2 dry reforming of methane (LTDRM). In this work, typical catalysts of SiO2 and γ-Al2O3 supported Ni and Ni-Ce were designed and prepared. Importantly, the difference in the chemical speciations of active sites on the Ni-based catalysts is revealed by advanced characterizations and further estimates respective catalytic performance for LTDRM. Results show that larger [ Ni n 0 ] particles mixed with [Ni-O-Sin]) species on the Ni/SiO2(R) make CH4 excessive decomposition, leading to poor activity and stability. Once the Ce species is doped, however, superior activity (59.0% CH4 and 59.8% CO2 conversions), stability and high H2/CO ratio (0.96) at 600 °C can be achieved on the Ni-Ce/SiO2(R), in comparison with other catalysts and even reported studies. The improved performance can be ascribed to the formation of integral ( [ Ni n 0 ] -[CeIII-□-CeIII]) species on the Ni-Ce/SiO2(R) catalyst, containing highly dispersed [ Ni n 0 ] particles and rich oxygen vacancies, which can synergistically establish a new stable balance between gasification of carbon species and CO2 dissociation. With respect to Ni-Ce/γ-Al2O3(R), the Ni and Ce precursors are easily captured by extra-framework Aln-OH groups and further form stable isolated ( [ Ni n 0 ] -[Ni-O-Aln]) and [CeIII-O-Aln] species. In such a case, both of them preferentially accelerate CO2 adsorption and dissociation, causing more carbon deposition due to the disproportionation of superfluous CO product. This deep distinguishment of chemical speciations of active sites can guide us to further develop new efficient Ni-based catalysts for LTDRM in the future.

Reactor performance of bubbling fluidized bed (BFB) and turbulent fluidized bed (TFB) was carefully examined and systematically compared using catalytic ozone decomposition as a model reaction, based on a complete mapping of local flow structures and spatial distributions of ozone conversion and solids holdup. TFB clearly has a higher conversion and shows better reactor performance than BFB as a result of the vigorously turbulent flow and the relatively homogeneous gas–solids mixing in TEB. Besides, the intensive interaction between gas and solids in TFB leads to greater gas–solids contact efficiency of TFB over that of BFB. Due to gas bypassing and backmixing caused by bubbling behaviours and two-phase structure, BFB deviates significantly from a plug flow reactor and sometimes from a continuously stirred tank reactor. The flow structures essentially dictate the reactor performance in the low-velocity fluidized beds.

Phosphogypsum is a solid waste sourced from the wet-process phosphoric acid industry, which causes severe environmental damages. Its utilization was limited by its high decomposition temperature and high energy consumption. Herein, an Fe-P slag, which is a solid waste that mainly comprises iron phosphide (FeP) and diiron phosphide (Fe2P), can dramatically decrease the decomposition temperature of phosphogypsum. It was found that the Fe-P slag and CaSO4 can react as shown in the following reaction equation: 2Fe1.5P+3CaSO4+6CO2→Ca3(PO4)2+Fe3O4+3SO2+6CO. Its reaction mecha-nism was further determined using the thermodynamic method. It was found that CaS was the key intermediate for this reaction. The CaSO4 conversion for this method can reach approximately 97% under the optimized roasting conditions: the molar ratio between Fe1.5P and CaSO4 of 2:3, roasting temperature of 900 °C, a roasting time of 8 h.

In this work, six energetic complexes were prepared and used as promoters for the hypergolic reaction of 1-ethyl-3-methylimidazolium cyanoborohydride [EMIM][BH3CN] and 90% H2O2. The structures of these compounds were studied by FT-IR spectroscopy, powder XRD, and single crystal X-ray diffraction. The results revealed that all the compounds were iso-structural and each metal centre was coordinated with four organic ligands and two counter ions. The decomposition temperatures of these compounds ranged from 169.6-255.9 °C. After adding 10 wt.% of prepared complexes to an ionic liquid, [EMIM][BH3CN], the shortest ignition delay time achieved was 94 ms. Moreover, the formed homogenous catalytic fuels had similar densities, thermal stabilities, as well as specific impulses similar to that of pure [EMIM][BH3CN]. The simple preparation method, excellent yield, as well as high performance of these compounds make them promising promoters for use in green hypergolic bipropellants.

Exploring an alternative strategy with high efficiency and low cost to abate formaldehyde (HCHO) in indoor environment, is of increasing significance for people’s health. CeO2 catalysts prepared by hydrothermal, precipitation and calcination methods were investigated for HCHO removal at ambient temperature. It is found that indoor fluorescent light visibly boosts the catalytic performance of CeO2 catalysts for HCHO decomposition at ambient temperature. Among the CeO2 catalysts, CeO2 prepared from hydrothermal method (CeO2-H) exhibits a superior catalytic performance and an excellent durability by eight recycle times. Based on the characterization and analysis, the excellent catalytic performance of CeO2-H is mainly contributed by its abundance of surface oxygen vacancies, and photogenerated electrons and hole activated by fluorescent light. This work shows a potential practicability in HCHO pollution elimination by taking full advantage of the existing lighting in indoor environments.

This study investigated catalytic decomposition and mass transfer of aqueous ozone promoted by Fe-Mn-Cu/γ-Al2O3 (Cat) in a rotating packed bed (RPB) for the first time. The results showed that the value of the overall decomposition rate constant of ozone (Kc) and overall volumetric mass transfer coefficient (KLa) are 4.28×10−3 s−1 and 11.60×10−3 s−1 respectively at an initial pH of 6, β of 40, C O 3 ( g ) of 60 mg·L−1 and QL of 85 L·h−1 in deionized water, respectively. Meanwhile, the Kc and KLa values of Fenhe water are 0.88×10−3 s−1 and 2.51×10−3 s−1 lower than deionized water, respectively. In addition, the Kc and KLa values in deionized water for the Cat/O3-RPB system are 44.86% and 47.41% higher than that for the Cat/O3-BR (bubbling reactor) system, respectively, indicating that the high gravity technology can facilitate the decomposition and mass transfer of ozone in heterogeneous catalytic ozonation and provide some insights into the industrial wastewater.

In recent years, MoS2 catalyzed/cocatalyzed Fenton/Fenton-like systems have attracted wide attention in the field of pollution control, but there are few studies on the effect of H2O2 feeding way on the whole Fenton process. Here, we report a new type of composite catalyst (MoS2-Fex) prepared in a simple way with highly dispersed iron to provide more active sites. MoS2-Fex was proved to possess selectivity for singlet oxygen (1O2) in effectively degrading sulfadiazine with a wide pH adaptability (4.0∼10.0). Importantly, the mechanism of the interaction between H2O2 and MoS2 on the Fenton reaction activity was revealed through the combination of experiment and density functional theory (DFT) calculations. Compared to the traditional “a large amount for one time” feeding way of H2O2, the “small amount for multiple times” of H2O2 feeding way can increase the degradation rate of sulfadiazine from 36.9% to 91.1% in the MoS2-Fex heterogeneous Fenton system. It is demonstrated that the “small amount for multiple times” of H2O2 feeding way can reduce the side reaction of decomposition of H2O2 by MoS2 and effectively improve the utilization rate of H2O2 and the stability of MoS2-Fex. Compared with Fe2O3-based Fenton system, MoS2-Fex can significantly save the amount of H2O2. Compared with nano-iron powder, the formation of iron sludge in MoS2-Fex system was significantly reduced. Furthermore, long-term degradation test showed that the MoS2-Fe75/H2O2 system could maintain the effectiveness of degrading organic pollutants for 10 days (or even longer). This study has a guiding significance for the large-scale treatment of industrial wastewater by improved Fenton technology in the future.

Formic acid is one of the key components in green chemistry being involved in energy storage, production of chemical intermediates and fuel components. Therefore the knowledge of its stability is of crucial importance and a systematic study of its decomposition is needed. The kinetics of formic acid decomposition to hydrogen and carbon dioxide was investigated in a laboratory-scale fixed bed reactor at 150–225 °C and atmospheric pressure. Palladium nanoparticles deposited on porous active carbon Sibunit were used as the heterogeneous catalyst. The catalyst was characterized by nitrogen physisorption and high-resolution transmission electron microscopy. The average palladium nanoparticle size was 5–6 nm. The impacts of mass transfer resistance and formic acid dimerization were negligible under the reaction conditions. Prolonged experiments revealed that the catalyst had a good stability. Hydrogen and carbon dioxide were the absolutely dominant reaction products, whereas the amounts of carbon monoxide and water were negligible. The experimental data were described with three kinetic models: first order kinetics, two-step adsorption-reaction model and multistep adsorption-decomposition model of formic acid. The multistep model gave the best description of the data.

An effective strategy involving a suitable carrier is needed to improve the dispersion, combustion and catalytic performances of catalyst nanoparticles. Herein, a Bi2WO6/g-C3N4 composite employing g-C3N4 as the catalyst carrier was prepared by a one-step in situ hydrothermal method, which was used as the combustion catalyst of solid propellants. The catalyst’s structure, morphology and its catalytic decomposition of several energetic materials were characterized by a series of analyses. The optimal ratio of g-C3N4 and Bi2WO6 was systematically determined. The results demonstrate that Bi2WO6/g-C3N4 (4:6) composite can diminish the decomposition temperatures of ammonium perchlorate (AP), cyclotrimethylenetrinitramine (RDX), dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) and cyclotrimethylenetrinitramine+nitrocellulose (RDX+NC) by 25.0, 5.2, 24.0 and 1.2 (4.9) °C, and reduce their apparent activation energy by 59.5, 116.7, 11.6 kJ·mol-1, respectively. Moreover, the laser ignition tests indicate that Bi2WO6/g-C3N4 can effectively promote the ignition performance of RDX and RDX+NC. A possible mechanism of Bi2WO6/g-C3N4 on AP was proposed. The g-C3N4 catalyst carrier is superior to GO carrier due to its low cost, simple synthesis process, improved combustion and catalytic performances, as well as abundant N content. These make it have broad engineering application prospects in solid propulsion and several other energetic materials.

CO2 hydrogenation to methanol was investigated over CuZnIn/MZrOx (M = La, Y or Ti) catalysts at 20 bar and at 225 °C with the purpose to elucidate the effects of the metal oxide promoter for ZrO2 and InOx for CuZnOx on reaction scheme of product formation, catalyst activity and product selectivity. Although the additives do not affect the overall scheme of product formation, they are relevant for the rates of direct CO2 conversion into methanol or CO and of methanol decomposition to CO and H2. This is due to their influence on dispersion of CuOx and the strength of basic sites for CO2 adsorption. Highly dispersed CuOx species are essential for CO2 conversion but not for methanol selectivity. The selectivity is improved over polymerized CuOx with strong basicity. This catalyst property can be controlled through promoting of (i) ZrO2 with La2O3/Y2O3 or (ii) CuZnOx with InOx. The latter promoter is crucial for hindering the undesired methanol decomposition to carbon monoxide.

Compared with hydrogen, ammonia has the advantages of high gravimetric hydrogen densities (17.8 wt.%), ease of storage and transportation as a chemical hydrogen storage medium, while its application in small-scale on-site hydrogen production scenarios is limited by the need for complex separation equipment during high purity hydrogen production. Therefore, the study of PEMFC, which can directly utilize ammonia decomposition gas, can greatly expand the application of fuel cells. In this paper, the output characteristics, fuel efficiency and the variation trend of hydrogen concentration and local current density in the anode channel of fuel cell with the output voltage of PEMFC fueled by ammonia decomposition gas were studied by experiment and simulation. The results indicate that the maximum output power of the hybrid fuel decreases by 9.6% compared with that of the pure hydrogen fuel at the same inlet hydrogen equivalent. When the molar concentration of hydrogen in the anode channel is less than 0.12, the output characteristics of PEMFC will be seriously affected. Employing ammonia decomposition gas as fuel, the efficiency corresponding to the maximum output power of PEMFC is approximately 47%, which is 10% lower than the maximum efficiency of pure hydrogen.

In this study, a graphitic carbon nitride (g-C3N4) based ternary catalyst CuO/CuFe2O4/g-C3N4 (CCCN) is successfully prepared thorough calcination method. After confirming the structure and composition of CCCN, the as-synthesized composites are utilized to activate persulfate (PS) for the degradation of organic contaminant. While using tetracycline hydrochloride (TC) as pollutant surrogate, the effects of initial pH, PS and catalyst concentration on the degradation rate are systematically studied. Under the optimized reaction condition, CCCN/PS is able to give 99% degradation extent and 74% chemical oxygen demand removal in assistance of simulated solar light, both of which are apparently greater than that of either CuO/CuFe2O4 and pristine g-C3N4. The great improvement in degradation can be assignable to the effective separation of photoinduced carriers thanks to the integration between CuO/CuFe2O4 and g-C3N4, as well as the increased reaction sites given by the g-C3N4 substrate. Moreover, the scavenging trials imply that the major oxidative matters involved in the decomposition are hydroxyl radicals (•OH), superoxide radicals (•O2−) and photo-induced holes (h+).

Alumina supported Pd catalyst (Pd/Al2O3) is active for complete oxidation of methane, while often suffers transient deactivation during the cold down process. Herein, heating and cooling cycle tests between 200 and 900°C and isothermal experiments at 650°C were conducted to investigate the influence of NOx on transient deactivation of Pd/θ-Al2O3 catalyst during the methane oxidation. It was found that the co-fed of NO alleviated transient deactivation in the cooling ramp from 800 to 500°C, which was resulted from the in situ formation of NO2 during the process of methane oxidation. Over the Pd/θ-Al2O3, thermogravimetric analysis and O2 temperature programmed oxidation measurements confirmed that transient deactivation was due to the decomposition of PdO particles and the hysteresis of Pd reoxidation, while the metal Pd entities were less active for methane oxidation than the PdO ones. CO pulse chemisorption and scanning transmission electron microscopy characterizations rule out the NO2 effect on Pd size change. Powder X-ray diffraction and X-ray photoelectron spectroscopy characterizations were used to obtain palladium status of Pd/θ-Al2O3 before and after reactions, indicating that in lean conditions at 650°C, the presence of NO2 increases the content of active PdO on the catalyst surface, thus benefits methane oxidation. Homogeneous reaction between CH4, O2, and NOx may be partially responsible for the alleviation above 650°C. The interesting research of alleviation in transient deactivation by NOx, the components co-existing in exhausts, are of great significance for the application.

A highly efficient and stable hydrotalcite-derived Cu-MgAlO catalyst was developed for the partial oxidation of cyclohexane with molecular oxygen. The physical-chemical properties of Cu-MgAlO catalysts were studied, and the results indicated that the copper component had been successfully introduced into the hydrotalcite unit layer structure. The catalytic reaction results showed that copper as the active species could activate C-H bond and effectively promote the decomposition of cyclohexyl hydroperoxide (CHHP) to KA oil. 8.3% of cyclohexane conversion and 82.9% of selectivity for KA oil were obtained over 9%Cu-MgAlO catalyst at 150 °C with 0.6 MPa of oxygen pressure for 2 h. Especially, its catalytic performance was still stable after five runs.

Cold-drawn pearlitic steel wire is irreplaceably used in industry owing to its outstanding mechanical property which is dominated by the cementite/ferrite (Fe3C/Fe) interfaces in the material. However, the fine structures of the Fe3C/Fe interfaces in the deformed wires are less known to date. In this work, transmission electron microscopic investigation was performed on the atomic structures of the interfaces with the Isaichev orientation relationship (OR) in the wires with progressive deformation strains. In addition to the effect of the dislocation/interface interactions, this work revealed that the deformation-induced partial decomposition of cementite plays an important role in the interface reconstruction during deformation. The interfacial carbon vacancies generated by cementite decomposition and particularly, the amorphization of cementite layers in the sample with e > 1 could effectively annihilated the interfacial dislocations and consequently relaxed the interfacial stress. The correlations between the interface structure changes and the mechanical properties of the wires were discussed.

Summary Conventional aqueous electrolytes suffer from a narrow voltage window due to water decomposition. Highly concentrated electrolytes expand the voltage window; however, they are limited by high cost and potential toxicity. Here, we develop a hydrogen bond-anchored electrolyte by introducing sulfolane as hydrogen bond acceptor to limit water activity. The designed electrolyte expands the voltage window to 3.4 V (1.3–4.7 V versus Li+/Li) and forms a hierarchical anode-electrolyte interphase to suppress the hydrogen evolution reaction. An aqueous Li4Ti5O12/LiMn2O4 full cell achieved 141 W h kg−1 for 300 cycles at 1 C and 125 W h kg−1 for 1,000 cycles at 5 C with a high Coulombic efficiency of 99.5%–99.9%. On-line electrochemical mass spectroscopy shows negligible hydrogen/oxygen gas evolution upon cycling, further confirming the stability of the designed electrolyte. This work demonstrates a rational and effective approach to suppress the hydrogen evolution reaction and achieve stable high-voltage aqueous batteries.

S-nitrosothiols (RSNOs) are an important group of nitric oxide (NO)-donating compounds with low toxicity and wide biomedical applications. In this paper, we, for the first time, demonstrate that the concentration of buffer remarkably affects the stability of RSNOs including naturally occurring S-nitrosoglutathione (GSNO) and synthetic S-nitroso-N-acetylpenicillamine (SNAP). For a solution with a high concentration of GSNO (e.g., 50 mM) and an initial near-neutral pH, the optimal buffer concentration is close to the GSNO concentration under our experimental conditions. A lower buffer concentration does not have adequate buffer capacity to resist the pH drop caused by GSNO decomposition. The decreased solution pH further accelerates GSNO decomposition because GSNO is most stable at near-neutral pH according to our density functional theory (DFT) calculations. A higher-than-optimal buffer concentration also reduces the GSNO stability because buffer ingredients including phosphate, Tris base, and HEPES consume NO/N2O3. In contrast to GSNO, the highest SNAP stability is obtained when the starting solution at a neutral pH does not contain buffer species, and the stability decreases as the buffer concentration increases. This is because SNAP is more stable at mildly acidic pH and the SNAP decomposition-induced pH drop stabilizes the donor. When the RSNO concentration is low (e.g., 1 mM), the buffer concentration also matters because any excess buffer accelerates the donor decomposition. Since the effect of buffer concentration was previously overlooked and suboptimal buffer concentrations were often used, this paper will aid in the formulation of RSNO solutions to obtain the maximum stability for prolonged storage and sustained NO release.

Developing low-temperature SO2-tolerant catalysts for the selective catalytic reduction of NOx is still a challenging task. The sulfation of active metal oxides and deposition of ammonium bisulfate deactivate catalysts, due to the difficult decomposition of the as-formed sulfate species at low temperatures ( 300°C); however, the SO2-tolerant mechanism of metal sulfate catalysts is still ambiguous. In this study, Fe2(SO4)3/TiO2 and Ce2(SO4)3/TiO2 catalysts were prepared using the corresponding metal sulfate salt as the precursor. These catalysts were tested for their low-temperature activity and SO2 tolerance activity. Compared to Ce2(SO4)3/TiO2, Fe2(SO4)3/TiO2 showed significantly better low-temperature activity and SO2 tolerance. It was demonstrated that less surface sulfate species formed on Fe2(SO4)3/TiO2 and Ce2(SO4)3/TiO2. However, the presence of NO and O2 could assist the decomposition of NH4HSO4 over Fe2(SO4)3/TiO2 at a lower temperature, endowing Fe2(SO4)3/TiO2 with better low-temperature SO2 tolerance than Ce2(SO4)3/TiO2. This study unraveled the SO2-tolerant mechanism of Fe2(SO4)3/TiO2 at lower temperatures (

DBD-catalytic system has been widely studied for volatile organic compounds abatement, whereas how to obtain high mineralization rate and low zone emission synchronously remains a challenge. In view of this, a new type of multi-stage DBD-catalytic system (MS1) was established to abatement toluene in this study. The mineralization rates of reactors IPC (63.81%) and MS1 (61.14%) were much higher than MS2, PPC1 and PPC2 reactors, which were 48.36%, 46.84%, and 5.8% at 33.8 (Vp-p) kV, respectively. For export ozone concentration, IPC reactor had the highest concentration of 160 ppm, and the values of reactors MS1, MS2, PPC1, and PPC2 were 79, 34.2, 34.25 and 29 ppm, respectively. The catalyst filled in zone II can be utilized to further decompose the residual toluene and intermediates and also promote the decomposition of ozone, which lead to the superior performance of the MS1 reactor. The influence of applied voltage, adsorbed amount, and discharge time on the toluene removal performance was investigated to optimize the operation parameters of MS1 reactor, their appropriate values were 28.3–31.1 (Vp-p) kV, 0.179–0.223 mmol, ∼1 h, respectively. Lastly, the contribution of disparate zones in multi-stage DBD-catalytic system to the toluene degradation were elucidated on the basis of the GC–MS results.

Porous carbon fibers catalysts have been prepared by electrospinning of Alcell lignin, a green carbon precursor, which could be obtained as by-product in wood-to-ethanol biorefineries. The addition of H3PO4, a well-known chemical activation agent, to the electrospinning lignin solutions, at different mass ratios and the use of different carbonization temperatures, between 500 and 1600 °C, were analyzed in order to obtain carbon fibers with a large variety of porosity and chemical surface properties. Isopropanol decomposition was used as a catalytic test. Phosphorus-containing carbon fibers showed acid character and high catalytic activity, achieving propylene selectivity of 100 % under inert atmosphere. However, the use of air atmosphere increases the isopropanol conversion but produces the formation of acetone, via oxidative dehydrogenation, at low temperatures (∼20 %). Ethanol and methanol decomposition were also evaluated in air stream for the most active phosphorus-containing carbon catalyst, showing improved alcohol conversions with minimal gasification of the carbon fibers. These results confirmed that phosphorus-containing carbon fibers prepared by electrospinning of lignin solutions were excellent catalysts for alcohol dehydration reactions.

Three different types of starch based bioplastic blends were synthesized. The FTIR spectra, XRD spectra and biodegradability test were used to characterize them. The FTIR spectra have shown the bands attributed to the stretching vibrations of hydroxyl groups (O-H) and carbonyl groups -CH, -CH2, C=O, C=C, C-O-C etc. The FTIR spectra confirmed the plastic nature of the samples by tracing the different functional groups of regular plastics. The XRD spectra have depicted the short range periodicity of the samples. Two samples have exhibited feeble diffraction peaks at 15.5°, 18.2°, 21.5° and 23.2°. The decomposition test found that these samples have appreciable percentage of volume degradability in the soil.

This work used CO2 as a co-reaction gas to realize in-situ deoxygenation of the bio-oil produced from microwave pyrolysis of biomass, and the mechanisms were thoroughly analyzed. Results showed that the bio-oil obtained at 550 °C (N2 atmosphere) had the highest yield of 29.24 wt.% with the higher heating value (HHV) of 20.27 MJ/kg. The introduction of CO2 atmosphere reduced the oxygen content of the bio-oil by 12.68 wt.% and increased the HHV by 26.43%. The oxygen mass balances demonstrated that the oil-O decreased by 31.45%, and the gas-O increased by 29.28% at CO2 atmosphere. The specific components in the bio-oil and pyrolytic gas were characterized. Furans in the bio-oil could react homogeneously with CO2 to generate CO at CO2 atmosphere, which was the main route to realize in-situ deoxygenation of the bio-oil. Meanwhile, stearic acid was selected as a model compound of the bio-oil to verify the action mechanisms of CO2 atmosphere. CO2 inhibited the decomposition of stearic acid to reduce the polycyclic aromatic hydrocarbons (PAHs) content in the bio-oil and promoted the generation of alkenes and CO. This study provides a novel perspective for the production of low-oxygen and high-quality bio-oil from biomass using CO2 reaction atmosphere.

Ferroelectric BaTiO3/ZnO heterojunction catalysts synthesised via the sol–gel method present obvious enhancements in spontaneous polarisation-driven Fenton-like catalytic activity. In this study, the oxidative decomposition of methylene blue (MB) dye was used as a model reaction. Pure BaTiO3-activated potassium monopersulphate (PMS) could decompose up to 48% of MB dye in an aqueous solution after 40 min. MB degradation rate firstly increased and then decreased as the ZnO content of the ferroelectric BaTiO3/ZnO heterojunction materials was increased. The maximum degradation rate of 100% and good cycling stability were observed when the BaTiO3:ZnO molar ratio was 1:1. Three active species, namely, holes (h+), sulphate radicals (SO4•−) and hydroxyl radicals (OH•), were produced following the spontaneous polarisation-driven catalytic degradation of the dye. Amongst these species, h+ and SO4•− were the main active species. Enhancements in the Fenton-like catalytic activity of BaTiO3/ZnO may be attributed to the formation of semiconductor heterojunctions, which could improve the spontaneous polarisation strength of ferroelectric BaTiO3, promote the effective separation of e−–h+ pairs and accelerate PMS activation. In summary, a novel PMS activation method was developed to provide a nontoxic, efficient and environmentally friendly technology for the degradation of organic pollutants.

GIS plays an irreplaceable role in the modern electrical system. However, partial discharge will inevitably occur under insulation defect conditions and may lead to serious insulation malfunction. The online monitoring method based on gas sensor is a feasible method to diagnose the severity of partial discharge in GIS. In this paper, metal oxide (TiO2, Fe2O3, NiO) cluster-modified single-layer graphene was proposed as a novel gas sensor to detect the characteristic components of SF6 decomposition products, SOF2 and SO2F2. Density functional theory calculations were carried out to study the gas adsorption and sensing mechanisms. The adsorption structures of gas molecules and the metal oxide cluster-modified single-layer graphene were built and optimized. Then, the most stable structure was selected to analyze the corresponding adsorption parameters. Calculation results showed that metal oxides decoration reduces the energy gap, improving the electrical conductivity and enhancing the adsorption activity of the graphene surface. According to DOS and CDD analyses, TiO2 modification obtained the best adsorption effect. Calculation results show that the metal-oxide-modified graphene sensor provides an effective method for effectively estimating the operating state of GIS by detecting SF6 decomposition products.

The design and fabrication of efficient catalysts for ammonium perchlorate (AP) decomposition is crucial for the performance of composite solid propellants. Herein, a novel hierarchical structure material of Cu-WO3 nanowire arrays on a nanoflower flake (Cu-WO3 NANF) was synthesized by a facile hydrothermal reaction. The negatively charged (001) polar facets of hexagonal WO3 and the action of Cu2+ induced growth were two important factors for the formation of hierarchical structures. The Cu-WO3 NANF exhibited remarkable catalytic activity for the thermal decomposition of AP. The temperature and activation energy of high temperature AP decomposition were significantly decreased to 378.3 °C and 147.01 kJ mol−1, respectively, which are attributed to the more oxygen vacancies and lower band gap energy of the Cu-WO3 NANF. Thus, it was excited at a lower heat to produce activated species. Under the strong adsorption of Cu-WO3 NANF surface Lewis acid, the activated species can react with NH3 quickly and deeply to produce N2, N2O, NO2 and NO gases, accompanied by a heat release of up to 1118 J g−1. The proposed catalytic mechanism was further corroborated by the in situ TG-MS result. This facile strategy provided a new idea for the design of hierarchical catalysts, and our research opened up a new field for WO3 applications.

Cellulose accounts for the largest proportion of lignocellulosic biomass. Herein, experimental and simulation studies are used to deeply understand the kinetic characteristics of the thermal decomposition of α-cellulose. The simulated data is in good agreement with the experimental data in the aspects of the conversion and the conversion rate versus temperature. The decomposition of α-cellulose, mainly occurring at 270–420 °C, induced an apparent activation energy ranging from 175.42 kJ/mol to 197.73 kJ/mol at a conversion of 10–90%. With 0.1–0.2 wt% K or Ca impregnation into the α-cellulose, the mean activation energy for pyrolysis was lowered (from 181.47 kJ/mol (for α-cellulose) to 141.11 kJ/mol (for 0.2 wt% K/α-cellulose) and 159.46 kJ/mol (for 0.1 wt% Ca/α-cellulose)) and higher amounts of liquid and gas products were produced. Furthermore, the addition of potassium and calcium increased the production of lower molecular weight components, such as furfural and its derivatives. The kinetic parameters of the α-cellulose pyrolysis were determined based on a nonlinear least-squares regression of the experimental data assuming first-order kinetics and correlated with the simulated result. The kinetic rate constants indicate that the predominant reaction pathway is from α-cellulose into a liquid product, rather than from α-cellulose into a gas product.

An effective decontamination method for soils remediation is a long-standing challenge. Herein, hydrogen peroxide (H2O2) was spontaneously produced in thin films generated by evaporating almost all the water. H2O2-sensitive test strips and oxidation of 2-hydroxybenzophenone to 2-hydroxyphenyl benzoate confirmed the generation of H2O2. Experiments in which reaction time and temperature were varied and established dependence of H2O2 production on the long-lasting thin films. H2O2 production was independence of irradiation and oxygen from air or dissolved oxygen. Spin-trapping probe experiments suggested that electric fields at the thin interfacial films enabled OH- to hydroxyl radicals and further recombination to H2O2. As a proof-of-principle experiment, perfluorooctanoic acid (PFOA) was effectively degraded on the thin films without catalysts and UV irradiation could further facilitate the degradation. A degradation mechanism was proposed involving the PFOA radicals on thin interfacial films and the subsequent decomposition of the radicals with successive loss of CF2. These findings have important implications for the development of decontamination method for soils remediation based on thin films, because thin film formats are ubiquitous at the surface of soils and when aerosols falling onto a substrate.

On-site produced hydrogen from ammonia decomposition can directly fuel solid oxide fuel cells (SOFCs) for power generation. The key issue in ammonia decomposition is to improve the activity and stability of the reaction at low temperatures. In this study, proton-conducting oxides, Ba(Zr,Y) O3-δ (BZY), were investigated as potential support materials to load Ni metal by a one-step impregnation method. The influence of Ni loading, Ba loading, and synthesis temperature, of Ni/BZY catalysts on the catalytic activity for ammonia decomposition were investigated. The Ni/BZY catalyst with Ba loading of 20 wt%, Ni loading of 30 wt%, and synthesized at 900 °C attained the highest ammonia conversion of 100% at 600 °C. The kinetics analysis revealed that for Ni/BZY catalyst, the hydrogen poisoning effect for ammonia decomposition was significantly suppressed. The reaction order of hydrogen for the optimized Ni/BZY catalyst was estimated as low as −0.07, which is the lowest to the best of our knowledge, resulting in the improvement in the activity. H2 temperature programmed reduction and desorption analysis results suggested that a strong interaction between Ni and BZY support as well as the hydrogen storage capability of the proton-conducting support might be responsible for the promotion of ammonia decomposition on Ni/BZY. Based on the experimental data, a mechanism of hydrogen spillover from Ni to BZY support is proposed.

2,4,6-Trinitroresorcinol (TNR), one main by-product in the dinitrobenzene (DNB) production process, is self-reactive substance and has led to tragic explosion incidents in China. In this article, the formation mechanism of TNR during the DNB production process was studied employing HPLC and HPLC-MS technique. Thermal decomposition behavior of TNR was also systematically studied by differential scanning calorimeter (DSC). The decomposition kinetics of TNR were investigated employing both iso-conversional (Friedman and Ozawa method) and model-fitting method. The formation mechanism of TNR during the dinitrobenzene (DNB) production is confirmed: The two by-products of dinitrophenol (DNP) and trinitrophenol (TNP) produced in the benzene mononitration stage are further nitrated to form tetranitrophenol (TTNP) in the mononitrobenzene (MNB) nitration stage. Then most of TTNP will be hydrolyzed to form the TNR during the water washing process. The decomposition process of TNR has been proven to follow three consecutive steps (A→B1→B2→B). The former two steps present autocatalytic behavior while the last step obeys N-order reaction model. The accuracy of the developed decomposition model and the obtained model parameters have been demonstrated by the comparison of the simulated and experimental DSC data and the activation energy obtained by both the iso-conversional method and model-fitting method. The same trend of experimental and simulated results about isothermal reaction further verify the building model.

Facilitating polysulfide conversion by electrocatalysis is a promising strategy to suppress shuttle effect in lithium-sulfur (Li-S) batteries, yet the active sites in electrocatalysts are gradually passivated by continuous formation of Li2S passivation layer over cycling, making it challenging to achieve steady conversion of sulfur species. Herein, a strategy of reactive Li2S collaborated with dual-directional Fe3C electrocatalyst is proposed to achieve fast and continuous conversion of sulfur species for drastically boosting the performance of Li-S batteries. During the reduction process, reactive Li2S with unique three-dimensional porous structure is precipitated on Fe3C surface, which not only shortens ion/electron diffusion path but also exposes and retains more active sites in Fe3C. While for the following oxidation process, Fe3C also promotes the decomposition of reactive Li2S to refresh electrocatalyst surface. Therefore, the high catalytic activity of Fe3C is well retained during the entire electrochemical process, as verified by comprehensive experimental and theoretical calculation results. Eventually, Fe3C enables stable operation of high-areal-capacity Li-S batteries (> 6.0 mAh cm−2) under a wide-temperature range (-10 to 40 °C). Our strategy of coupling reactive Li2S with a bidirectional electrocatalyst provides a new avenue for developing high-energy and wide-temperature Li-S batteries.

Conversion of waste lipid biomass into renewable fuels using sub- and supercritical water provides an alternative green approach in contrast with the current treatment methods. However, the reaction network of unsaturated lipids in sub- and supercritical water has not been clarified. Unsaturated lipids are found abundantly in waste lipid biomass, making the establishment of their reaction network essential. In this study, the reaction of crotonic acid (CA) as a model unsaturated lipid in sub- and supercritical water was clarified through an in-depth study of its reaction pathways and kinetics. The experiments were conducted at temperatures from 300 to 415 °C, a pressure of 25 MPa, and residence times from 30 to 150 s in a continuous flow process. The main products in the initial stage of the reaction were butyric acid (BA) and propene. Based on the temperature dependence experiments, the CA conversion increased along with temperature and residence time. Based on the product distribution, two main decomposition pathways were identified in the initial stage of the CA reaction. The first is CA direct decarboxylation and the second is CA hydrogenation followed by BA decarbonylation. Examination of the kinetic rates revealed that the reaction mainly proceeds via CA direct decarboxylation, contrary to the results reported in previous studies. The findings demonstrated that the role of water can change according to the conditions and reactions employed. This was proven by the evident variation of kinetic rate constants under sub- and supercritical conditions and is reflected in the Arrhenius plot.

Hydrogen peroxide is a green propellant which apart from space propulsion is used in various industrial applications. Though hydrazine was used initially, the nature of hydrazine which is a toxic, carcinogenic and hazardous fuel resulted in various space agencies’ interest in green propellants. The essential step for high test peroxide (HTP) as a green mono propellant realization is on development of a reliable, effective, long life catalytic beds which are not affected by catalytic poisoning and impurities. In the present study, a 3D model is developed using COMSOL Multiphysics software to know the catalytic decomposition of 30% hydrogen peroxide flowing inside a 3 mm diameter 300 mm length channel. The effect of annular silver catalyst (I.D – 1.6 mm, O.D. – 2 mm, length 10 mm) on decomposition rate is studied in detail. The positioning of silver catalyst bed and number of beds increased the reaction rate with varying pressure drop. Among the variations simulated, the 4 catalyst model gives the better performance and gets decomposed to a greater extent. This model will help in the design of a micro thruster which can operate efficiently with low pressure drop.

In this study, the effect of unintentional nitrogen incorporation on n-type doping of β-Ga2O3 films grown by plasma-assisted molecular beam epitaxy has been demonstrated. The nitrogen atoms, with a concentration as high as 2×1019 cm-3, are confirmed to originate from the decomposition of the pyrolytic boron nitride (PBN) crucible in the plasma source. These atoms act as acceptors in β-Ga2O3 and severely compensate the Si-donors, thus, hindering the generation of n-type β-Ga2O3. Instead, a quartz (SiO2) crucible free of nitrogen atom can overcome this issue, leading to the successful generation of n-type β-Ga2O3 with tunable electron concentration in the range 5.0×1016-2.6×1019 cm-3.

The objective of this work is to study the coupling power of hydrogen peroxide and ozone (Peroxone) on the decontamination of soil contaminated by Total Petroleum Hydrocarbons (TPH). The oxidation takes place simultaneously by the exchange of electrons, which will activate the decomposition of hydrogen peroxide into OH radicals. In this study, we examined the effect of various parameters (level of contamination, type of soil, and age of contamination). The results obtained showed the potential of chemical oxidation on the cleaning of soils contaminated by hydrocarbons and that the structure of this chemical has a crucial impact on the elimination kinetics.

Traditional hard/soft template approaches to hollow structures suffer from tedious procedures and time-consuming. Compare to these methods, self-template approaches usually gain advantages of step-economy. Herein, solid spherical Ni-glycolate/Ni microspheres were initially synthesized by reacting nickel (II) with ethylene glycol at high temperature. The source of nickel (II) has determinable impact on the formation of Ni-glycolate/Ni. Specially, nickel acetate as sources yielded Ni-glycolate/Ni, while nickel nitrate as precursor cannot. The plausible reason for this result can be attributed to the different acidity of the system caused by the dissolution of nickelacetate and nickel nitrate. By reacting with thioacetamide (TAA) under solvothermal condition and heat treatment, the Ni-glycolate/Ni microspheres were further employed as self-template for direct the formation of hollow NiS microspheres. The driving force for converting Ni-glycolate/Ni into hollow NiS could be attributed to Kirkendall effect resulted from the different diffusion rates of nickel ions (from Ni-glycolate/Ni) and sulfur ions from the decomposition of TAA. When applied as electrode material of supercapacitors, the formed hollow NiS microspheres exhibited a specific capacitance of 1674 F/g at 1 A/g with excellent rate capability and cycling performance. The corresponding asymmetric device of NiS//AC delivered a high energy density of 43.3 Wh/kg at the power density of 850.3 W/kg. These achievements pave innovative synthetic approach to hollow structures for many other practical applications.

Selective catalytic reduction (SCR) of NOx with NH3 has been widely used for NOx emission control, but commercial catalysts inevitably suffer severe deactivation in SO2-containing stack gases at low temperatures because the ammonium bisulfate (NH4HSO4, ABS) formed in SCR blocks the surface active sites. We resolve this issue by developing a TiO2-supported single-atom Mo catalyst (Mo1/TiO2) that decomposes ABS at ∼225 °C, far lower than the dew point of ABS (∼260 °C). Single Mo atoms paired with the neighboring surface Ti atoms function as Mo–Ti acid–base dual sites, which respectively adsorb the NH4+ and HSO4− of ABS. After the oxidation of NH4+ by surface lattice oxygen on the Mo sites, electrons left behind on the dual sites are localized around the Fermi level, which allows them to transfer to the adsorbed HSO4− on the Ti sites, thus releasing SO2 at low temperatures. The Mo1/TiO2 catalyst with Mo–Ti acid–base dual sites enables the decomposition of ABS at low temperatures, and thus this work provides a way to effectively control NOx emission particularly from industrial boilers.

Benzoyl peroxide (BPO) is a common cross-linking agent and initiator that is widely used in the chemical industry. The instability of a substance may be influenced by the presence of impurities; therefore, the thermal hazard of organic peroxides under contamination has always been a topic of interest. In this study, the effects of hexanoic acid (HAA) on the thermal decomposition of BPO were investigated using differential scanning calorimetry (DSC; 2.0, 4.0, 6.0, 8.0, and 10.0 °C/min) experiments. By using the Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa kinetic models, the progress of the obtained DSC curve was fitted linearly, and the thermokinetic parameters of BPO in the presence of HAA were further calculated. The two apparent activation energy calculations consistently indicated that HAA increased the thermal hazard of BPO. In addition, the Coats-Redfern model was adopted to compute the decomposition mechanism function of each phase of the material, and Gaussian 16 was used to determine the atomic bonding levels between the molecules to discover the thermal decomposition reaction path of BPO under the effect of HAA. The study results can be used as a reference for the loss prevention and control of BPO in practical engineering applications.

Metal oxide/hydroxide-based nanocomposite adsorbents with porous supporting matrices have been recognized as efficient adsorbents for phosphorus recovery. Aiming at satisfying increasingly restrictive environmental requirements involving improving metal site utilization and lowering metal leakage risk, a glycol-solvothermal confined-space synthesis strategy was proposed for the fabrication of FeOOH/anion exchanger nanocomposites (Fe/900s) with enhanced metal site utilization and reduced metal leakage risk. Compared to composites prepared using alkaline precipitation methods, Fe/900s performed comparably, with a high adsorption capacity of 19.05 mg-P/g with an initial concentration of 10 mg-P/L, a high adsorption selectivity of 8.2 mg-P/g in the presence of 500 mg-SO42−/L, and high long-term resilience (with a capacity loss of ~14% after five cycles), along with substantially lower Fe loading amount (4.11 wt.%) and Fe leakage percentage. Mechanistic investigation demonstrated that contribution of the specific FeOOH sites to phosphate adsorption increased substantially (up to 50.97% under the optimal conditions), in which Fe(III)-OH was the dominant efficient species. The side effects of an excessively long reaction time, which included quaternary ammonium decomposition, FeOOH aggregation, and Fe(III) reduction, were discussed as guidance for optimizing the synthesis strategy. The glycol-solvothermal strategy provides a facile solution to environmental problems through nanocrystal growth engineering in a confined space.

The direct nonoxidative conversion of methane (CH4) to valuable chemicals has attracted increasing interest. However, the carbon deposition will inevitably occur due to CH4 decomposition at high temperature. Here, we report the conversion of CH4 assisted by non-thermal plasma into olefins and H2 over a Pd/CeO2 catalyst. The addition of the plasma could effectively enhance the anti-coking performance of the catalyst, facilitating the conversion of CH4. The interaction between plasma and catalyst was explored in detail. The energized electron and ions generated by plasma could interact with the adsorbed CH3 species to efficiently suppress the consequent dehydrogenation of the adsorbed CH3, accelerating the desorption of the CH3 species from the surface of the catalyst, thus reducing the amount of carbon deposition on the catalyst surface. The highly efficient catalyst assisted by plasma is effective in enhancing the CH4 conversion and suppressing the carbon deposition, which deserves to be widely applied in catalysis.

Caprolactam is the main compound of nylon 6 waste fishing nets (WFNs) and its recovery conserves natural resources, maximizes WFNs economic performance, and closes the circular economy loop of the fishing net industry. Within the framework and as a part of the Healthy Seas’ initiative to clean the oceans from waste fishing nets (WFNs), and to valorise it, this research aims to study the catalytic pyrolysis behaviour of the WFNs extracted from oceans in order to study their potential applications in the energy conversion field. The catalytic pyrolysis experiments of WFNs over ZSM-5 Zeolite catalyst (2.5, 5, 10, 20, 50 wt%) were conducted using thermogravimetry (TG) coupled with Fourier-transform infrared spectroscopy (TG-FTIR) and gas chromatography–mass spectrometry (GC-MS) at different heating rates (5–30 °C/min). Also, the kinetics of ZSM-5/WFNs catalytic pyrolysis was studied by model-free methods (KAS, FWO, and Friedman). In addition, the distributed activation energy model (DAEM) and the independent parallel reaction kinetic model (IPR) combined with the optimization algorithm were used to fit the TGA-DTG experimental data and to calculate the parameters that can achieve the minimum deviation. The TGA results showed that the main decomposition zone was located in the range 342–476 °C with a total weight loss 83-75 wt% (based on the amount of catalyst). Meanwhile, FTIR and GC-MS results manifested that alkyl C–H stretch functional group, carbonyl functional group (C O), and caprolactam (83.15%; at 20 wt% of ZSM-5) are the main groups and volatile compounds in the decomposed WFNs samples. The model-free kinetics analysis showed that all activation energies were estimated at 112 kJ/mol (WFNs) and 158, 230, 197, 201, and 220 kJ/mol for ZSM-5/WFNs samples (2.5, 5, 10, 20, 50 wt%). At the same time, DAEM and IPR models proved a high prediction to fit TG curves at all heating rates. Based on these results, catalytic pyrolysis using 20 wt% of ZSM-5 can be used as a promising technology for extracting caprolactam from WFNs with high yield (83%). The recovered caprolactam can be used in the production of nylon fibres, nylon thin films, carpets, textiles, resins, etc.

In the first step of this study, the hydrothermal carbonization (HTC) of cellulose was performed at 225 and 250 °C for 4, 8 and 12 h. The effect of temperature and residence time on hydrochar (HC) yields and characteristics was investigated, and the highest hydrochar yield had a heating value of 21.06 MJ/kg. In the second step, cellulose and hydrochar-derived cellulose was subjected to fast online pyrolysis at 500, 600 and 700 °C, using a pyrolysis-gas chromatography-mass spectrometry system. The HTC process significantly affected the pyrolysis products. The major decomposition product resulting from the fast pyrolysis of cellulose was levoglucosan, but at all tested temperatures, 2-methylfuran was the major product from hydrochars. Increasing the pyrolysis temperature caused a decrease in the relative yield of 2-methhyfuran. Another prominent compound observed in pyrolyzates was 2,5-dimethylfuran. The relative yields of these two compounds decreased when the residence time of the HTC process was increased. The highest 2-methylfuran selectivity was 67.4%, while the highest 2,5-dimethylfuran selectivity among the furanic compounds was 24.0%. This study demonstrated that, by combining HTC and pyrolysis processes, fine chemicals can be produced from cellulose.

We have shown previously that exposing bacteria to tetrachlorocatechol (TCC) and sodium azide (NaN3) together causes synergistic cytotoxicity in a biphasic mode. However, the underlying chemical mechanism remains unclear. In this study, an unexpected ring-contraction 3(2H)-furanone and two quinoid-compounds were identified as the major and minor reaction products, respectively; and two unusual azido-substituted chloro-O-semiquinone radicals were detected and characterized as the major radical intermediates by complementary applications of direct ESR, HPLC/ESI-Q-TOF and high-resolution MS studies with nitrogen-15 isotope-labeled NaN3. Taken together, we proposed a novel molecular mechanism for the reaction of TCC/NaN3: N3- may attack on tetrachloro-O-semiquinone radical, forming two transient 4-azido-3,5,6-trichloro- and 4,5-diazido-3,6-dichloro-O-semiquinone radicals, consecutively. The second-radical intermediate may either undergo an unusual zwitt-azido cleavage to form the less-toxic ring-contraction 3(2H)-furanone product, or further oxidize to form the more toxic quinoid-product 4-amino-5-azido-3,6-dichloro-O-benzoquinone. A good correlation was observed between the biphasic formation of this toxic quinone due to the two competing decomposition pathways of the radical intermediate and the biphasic synergism between TCC and NaN3, which are dependent on their molar-ratios. This is the first report of detection and identification of two unique azido-substituted chloro-O-semiquinone radicals, and an unprecedented ring-contraction mechanism via an unusually mild and facile zwitt-azido rearrangement.

Using molten NaNO3–KNO3–NaNO2 for biowaste pyrolysis provides a promising way to synergize the utilization of biowaste and fluctuating solar energy. However, the diversity of lignocellulosic biowaste and violent decomposition complicated the interactions between natural constituents. In this study, the pyrolysis behavior of woody and agricultural herbaceous lignocellulosic biowaste in molten salts was comprehensively investigated at 300 °C. Through the selective removal of partial hemicellulose or lignin, the specific role of the original structure on the products formation characteristics was further estimated. The results showed that more volatiles were released from the hemicellulose-enriched agricultural herbaceous biowaste than cellulose-enriched woody biowaste. The yields of water and organic liquids from hemicellulose or lignin removal were higher than that of raw biowaste. Specifically, hemicellulose dominated the generation of nitrogenous substances in the liquid products. As for the gas product, its yield from the hemicellulose removal sample was higher than raw biowaste but it decreased after removing lignin. Lignin was the primary contributor to the combustible CO, H2, and CH4, while the production of CO2 was more affected by hemicellulose. The lignin would compete with hemicellulose and be superior to the latter in the reaction with molten salt.

Biochar addition can enhance soil quality and sequester carbon. However, changes in soil organic matter (SOM) molecular compositions in response to long‐term biochar addition have rarely been studied. Therefore, we quantified soil organic carbon fractions, carbon‐cycling enzyme activities, and a range of organic compounds and lignin‐derived phenols in the rhizosphere and bulk soils in different rice growth stages in the 8‐year field trial with biochar application rates of 0 (BC‐0), 4.5 (BC‐L), and 13.5 t ha−1 year−1 (BC‐H). We found that higher amounts of biochar addition (BC‐H) increased labile organic carbon (LOC), dissolved organic carbon (DOC) and particulate organic carbon (POC), and promoted activities of α‐1,4‐glucosidase, β‐D‐cellobiohydrolase and β‐1,4‐xylosidase; in contrast, BC‐L treatment reduced activities of these enzymes. The concentrations of dichloromethane/methanol‐extractable plant‐ and microbial‐derived organic compounds in the rhizosphere and bulk soils at tillering decreased significantly in the treatment with low amount of biochar addition. BC‐L also significantly altered the concentrations of extracted compounds in the rhizosphere soil at tillering and harvest. Concentration of lignin in the bulk soil was significantly reduced in BC‐L at tillering (by 19%) and harvest (by 28%). The concentrations of extracted compounds (e.g., n‐alkanols, n‐alkanoic acids, steroids, and carbohydrates) and lignin were generally significantly higher in the bulk than the rhizosphere soil at tillering and harvest. Long‐term biochar application (BC‐H) promoted lignin decomposition in the bulk soil (at tillering) and the rhizosphere soil (at harvest). Hence, biochar decreased stability of lignin in paddy soil. Our study provided evidence that long‐term biochar application changed the molecular composition and dynamics of degradation of SOM. These results deepen our understanding of the mechanisms governing SOM stability in agricultural ecosystems.

The performances of heterogeneous catalysts can be effectively tuned by changing the catalyst structures. Here we report a controllable nitrile synthesis from alcohol ammoxidation, where the nitrile hydration side reaction could be efficiently prevented by changing the manganese oxide catalysts. α-Mn2O3 based catalysts are highly selective for nitrile synthesis, but MnO2-based catalysts including α, β, γ, and δ phases favour the amide production from tandem ammoxidation and hydration steps. Multiple structural, kinetic, and spectroscopic investigations reveal that water decomposition is hindered on α-Mn2O3, thus to switch off the nitrile hydration. In addition, the selectivity-control feature of manganese oxide catalysts is mainly related to their crystalline nature rather than oxide morphology, although the morphological issue is usually regarded as a crucial factor in many reactions.

Catalytic ammonia (NH3) decomposition has been identified as a COx-free, sustainable hydrogen production method for fuel cell applications. In this study, the performance of plasma–catalyst-based NH3 decomposition over ruthenium (Ru/Al2O3) and soda glass (SiO2) catalytic materials at atmospheric pressure and ambient temperature was investigated. NH3 decomposition reactions were conducted in a dielectric barrier discharge plasma plate-type reactor. NH3 was fed into the plate catalytic microreactor at flow rates of 0.1–1 L/min and plasma voltages of 12–18 kV. Compared to plasma NH3 decomposition without a catalyst, plasma–catalyst-based NH3 decomposition showed a significant enhancement of the hydrogen production rate and energy efficiency. Furthermore, the hydrogen concentration results obtained over the Ru/Al2O3 catalyst were higher than those over the SiO2 catalyst because Ru/Al2O3 possesses good electronic properties and exhibits high sensitivity to NH3 decomposition. In addition, the resulting plasma heat enhanced the activation of the catalytic material, subsequently leading to an increase in the hydrogen production rate from NH3. The maximum conversion rates were 85.65% and 84.39% for Ru/Al2O3 and SiO2, respectively. Moreover, the energy efficiency of NH3 decomposition over the Ru-based catalyst material was higher than that over the SiO2 material. The presence of the catalyst active sites and plasma enhanced the mean electron energy, which could enhance the dissociation of NH3. It can be concluded that the SiO2 material can be utilised as a catalyst and that its combination with plasma accelerates the decomposition process of NH3 and incurs a lower cost compared to Ru materials.