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The oxygen carrier (OC) agglomeration is an important factor limiting the development of biomass chemical looping gasification (CLG) technology. However, the agglomeration behavior of OC is not clear under multiple perspectives of reaction conditions. In this study, we investigated the Fe-based OC agglomeration behavior during CLG from three perspectives of biomass species, reaction temperature and steam/biomass (S/B). The results showed that biomass with high ash and K content was easy to form more low melting point substances, causing a lower deformation temperature (DT) and more severe agglomeration of OC after CLG. Moreover, with the increase of reaction temperature from 700 °C to 900 °C, the DT of OC decreased by 6.8 %, while the average particle size and agglomeration degree of OC increased by 26.2 % and 209.5 %, respectively. Although high temperature was beneficial for improving reaction performance and shortening reaction time, the excessive temperature would cause severe agglomeration and inhibit CLG process. In addition, the higher the S/B was, the more severe the agglomeration became. With the increase of S/B from 0 to 1.8, the DT of OC decreased by 3.2 %, while the average particle size and agglomeration degree of OC increased by 28.2 % and 75.5 %, respectively. The excessive S/B would form more KOH and NaOH with lower melting point, exacerbating the OC agglomeration and inhibiting the gasification. [Display omitted] • High ash content in biomass is easy to cause lower DT and severe agglomeration. • High K content in biomass with similar ash content induces more agglomeration. • The higher the temperature is, the more severe the agglomeration becomes. • High S/B causes larger average particle size and lower DT of oxygen carrier. • The excessive S/B will exacerbate the agglomeration and inhibit the gasification. [ABSTRACT FROM AUTHOR]

Biochar chemical looping gasification (CLG) is a novel technology to obtain hydrogen-rich syngas, high gasification efficiency and low carbon deposition. This study investigates the effect of preparation methods, Fe loadings, active components, Ca loadings and steam/biochar (S/C) to achieve the optimal oxygen carrier. The results show that coprecipitation is the best preparation method to gain highest efficiency, redox activity and dispersion. H 2 production increases visibly with the increase of Fe loading, while efficiencies increase firstly and then decrease. There is an evident effect of active component on CLG. Oxygen carrier based on Fe/Ca performs a lower carbon deposition, higher H 2 production and efficiency. With the increase of Ca loading, H 2 production and efficiencies increase firstly and then decrease. S/C has an obvious effect on CLG performance. 1.5 is the optimal S/C to achieve high H 2 concentration of 67.35%, the highest gas production of 1.34 Nm3/kg and gasification efficiency of 96.93%. Image 1 • Fe/Ca-based oxygen carrier performs synergistic catalysis in biochar CLG process. • Coprecipitation method is conducive to dispersion, redox reaction and efficiency. • The optimal Fe loading is 1.5 with the highest efficiency and interaction of carrier. • 1.0 is the best Ca loading to gain highest efficiencies and lowest carbon deposition. • Steam/biochar has an obvious effect on H 2 production and efficiencies. [ABSTRACT FROM AUTHOR]

A novel continuous reactor with shaftless spiral for chemical looping gasification (CLG) of rice husk is expected to propose for application and optimal parameter. Syngas concentration, efficiency, lower heating value of syngas and micromorphology structure were investigated under different conditions of temperature, ratio of OC and rice husk (O/C) and speed. The results indicated that CLG in the shaftless spiral reactor had a better performance. The gas yield, carbon conversion efficiency and gasification efficiency were 73.33%, 63.92% and 98.26% higher than that of fixed-bed reactor, respectively. Further, higher temperature obviously enhanced gas production and efficiency but was easy to cause agglomeration and harmful to OC regeneration. Furthermore, lower O/C would increase the combustible gas production but cause a serious sintering and decrease gas production and carbon conversion efficiency. Moreover, lower speed would promote the gas production and efficiency but cause agglomeration. In addition, lower speed had a greater effect on H 2 yield than CO. As a result, the shaftless spiral reactor was beneficial to CLG. The best performance with gas production of 70.99% and gasification efficiency of 67.80% was obtained in shaftless spiral reactor under the optimal parameters with temperature of 800 °C, O/C of 1.5 and speed of 5.5 r/min. • CLG of rice husk in the shaftless spiral reactor had a better performance. • Higher temperature enhanced gas yield and efficiency but harmed to OC regeneration. • Insufficient OC caused low gas production and deep reduction of Fe 2 O 3 into Fe. • Lower speed would promote the gas production and efficiency but cause agglomeration. • Lower speed had a greater effect on H 2 yield than that of CO. [ABSTRACT FROM AUTHOR]

The chemical looping gasification (CLG) of rice husk was conducted in a fixed bed reactor to analyze the effects of the ratio of oxygen carrier to rice husk (O/C), temperature, residence time and preparation methods of Fe-based oxygen carriers. The yield of gas, H 2 /CO, lower heating value of syngas (LHV), conversion efficiency and performance parameters were analyzed to obtain CLG reaction characterization and optimal reaction conditions. Results showed that when O/C increased from 0.5 to 3.0, the gas production, H 2 /CO, CO 2 yield and carbon conversion efficiency gradually increased, while the yield of H 2 , CO and CH 4 and LHV gradually decreased. At the same time, a highest gasification efficiency was obtained when O/C was 1.5. As increasing temperature, the gas production, CO yield, carbon conversion efficiency and gasification efficiency gradually increased, while the yield of H 2 , CH 4 and CO 2 , H 2 /CO and LHV gradually decreased. Sintering and agglomeration was obvious when the temperature was higher than 850 °C. When the reaction time increased from 10 min to 60 min, the gas production, CO yield, carbon conversion efficiency and gasification efficiency gradually increased, but the yield of H 2 , H 2 /CO and LHV decreased, among which 30 min was the best reaction residence time. In addition, coprecipitation was the best preparation method among several preparation methods of oxygen carrier. Finally, O/C of 1.5, 800 °C, 30 min and coprecipitation preparation method of oxygen carrier were the optimal parameters to obtain a gasification efficiency of 26.88%, H 2 content of 35.64%, syngas content of 56.40%, H 2 /CO ratio of 1.72 and LHV of 12.25 MJ/Nm3. • O/C of 1.5 can obtain a high gasification efficiency and H 2 /CO. • Higher temperature enhances conversion efficiency but decreases H 2 /CO and LHV. • Longer reaction time can improve gas production and conversion efficiency. • Oxygen carrier by coprecipitation method converts to FeAl 2 O 4 after CLG. • Coprecipitation is the optimal preparation method to obtain high CLG performance. [ABSTRACT FROM AUTHOR]

The large-scale application of bio-oil has been restricted due to its high O content, strong acidity and low heat value. Therefore, the hydrodeoxygenation (HDO) of phenols, acids, and ketones as bio-oil model compounds for hydrocarbon fuel via Ni-based catalysts modified by metal oxides (Al, La and Ga) was investigated. The results showed that the hydrocarbon content was over 70.65% when the mixed supported catalysts Ni/HZSM-5-γ-Al 2 O 3 , Ni/HBeta-La 2 O 3 and Ni/HBeta-Ga 2 O 3 were used for the HDO of guaiacol (GUA). Cyclic hydrocarbons and aromatic hydrocarbons were the main products. Among these catalysts, Ni/HZSM-5-γ-Al 2 O 3 was the most effective in the HDO of acetic acid. The conversion and hydrocarbon content were 100.00% and 88.62%, respectively. Long-chain alkanes were the main components of the upgraded liquid. Ni/HZSM-5-γ-Al 2 O 3 was beneficial for the HDO of hydroxyacetone with 100.00% conversion, 80.30% hydrocarbon content and 48.67% yield. The HDO pathways of GUA, acetic acid and hydroxyacetone were as follows: 1) GUA was mainly converted into benzene and its derivatives by transmethylation, isomerization and hydrogenation (HYD). 2) Acetic acid was converted to long-chain alkanes by HYD, self-condensation, saturated HYD and isomerization. 3) Hydroxyacetone was converted into long-chain alkanes by HYD, self-condensation, demethylation, aldol condensation and saturated HYD. This work provides basic data for obtaining renewable hydrocarbon fuel from biomass via HDO with a low-cost catalyst. Three nickel-based catalysts modified by metal oxides (i.e., γ-Al 2 O 3 , La 2 O 3 and Ga 2 O 3) were prepared by the impregnation method.The modified nickel-based catalysts were applied to the HDO of bio-oil model compounds (GUA, acetic acid and hydroxyacetone).The most effective catalyst for the HDO of GUA, acetic acid and hydroxyacetone was the Ni/HZSM-5-γ-Al 2 O 3 catalyst. The upgraded liquid was mainly cyclic hydrocarbons and aromatic hydrocarbons after HDO of GUA, but the upgraded liquid was focused on long-chain alkanes after HDO of acetic acid and hydroxyacetone. Image 1 • HDO of model bio-oil for hydrocarbon fuel. • Ni/HZSM-5-γ-Al 2 O 3 was suitable for HDO of phenols, acids and ketones. • Long-chain alkanes, cyclic hydrocarbons and aromatic hydrocarbons were the main composition. • The HDO of GUA, acidic acid and hydroxyacetone were investigated. [ABSTRACT FROM AUTHOR]

The simulations of combustion and NO X emissions process are conducted by computational fluid dynamics method with comprehensive physical and chemical models in a municipal solid waste incinerator. This study focused on the effects of primary NO X control methods (different loads, over fire air, the ratios of secondary air and over fire air) and secondary NO X control methods (selective non-catalytic reduction process) on NO X emission and combustion characteristic. Results showed that the moisture evaporation rate, volatile release rate, char burning rate, temperature and the strength of flow velocity decreased as decreasing the operating load. However, the NO X emission of furnace outlet increased from 273.18 mg/Nm3 to 602.10 mg/Nm3. 100% operating load was the best condition to obtain a lowest NO X emission and a best combustion characteristic among different loads. In addition, the combustion strategy combining secondary air and over fire air could improve the combustion performance and reduce NO X emission. Further, a higher over fire air ratio was conducive to the formation of strong swirl flow and the enhancement of flow velocity strength in the flue. The optimal over fire air ratio was 31%–35% with NO X emission of 267.05 mg/Nm3 to 273.18 mg/Nm3 and residence time of 2.75 s–3.03 s. Moreover, ammonia based selective non-catalytic reduction process, better than urea, achieved a NO X emission of 132.41 mg/Nm3, a NO X removal efficiency of 51.50% and NH 3 slip of 11.08 mg/Nm3 or 6.71 ppm. The study indicated that the optimal NO X control method was a condition of 100% load, combining with over fire air and 31% and 35% over fire air ratio. Moreover, the best secondary NO X control method was the ammonia based selective non-catalytic reduction process. • The NO X emission of furnace outlet increased as decreasing the operating load. • Operating load, OFA, OFA ratio and SNCR did have an impact on flow velocity strength. • OFA affected the combustion characteristics and NO X emission. • The optimal OFA ratio was 31%–35% with NO X emission of 267.05–273.18 mg/Nm3. • Ammonia based SNCR, with a NO X removal efficiency of 51.50%, was better than urea. [ABSTRACT FROM AUTHOR]

Highlights • Injection positions did have a strong impact on NO X removal efficiency and NH 3 slip. • SNCR injection speed had an optimal speed but not the higher the better. • 13.80 m/s was the optimal SNCR injection speed. • SNCR injection ratios clearly affected the NO X removal efficiency and NH 3 slip. • The best SNCR injection ratio was the ratio (SNCR-1:SNCR-2:SNCR-3) of 6:3:1. Abstract The combustion of municipal solid waste and ammonia based selective non-catalytic reduction (SNCR) process in a moving-grate incinerator was simulated based on the computational fluid dynamics method. The combustion characteristics, overall temperature level, NO X emission, NO X removal efficiency and NH 3 slip were analyzed to determine the optimal SNCR injection positions, injection speeds and injection ratios. Results showed that there was no difference in the furnace temperature and O 2 concentration under different SNCR injection positions, speeds and ratios. Moreover, the temperatures of SNCR injection zones were in the SNCR reaction temperature range of 800 °C–1100 °C under different SNCR injection positions, speeds and ratios. Further, injection positions strongly affected NO X removal efficiency and NH 3 slip. Ammonia should be injected in layer and in the front region within the suitable temperature range as much as possible. Furthermore, SNCR injection speed had an optimal speed, which was 13.80 m/s with NO X removal efficiency of 51.50% and NH 3 slip of 11.08 mg/Nm3. In addition, there was a strong impact on NO X removal efficiency and NH 3 slip under different SNCR injection ratios. Increasing the ratio of SNCR-1 (the first row of SNCR) was conducive to the improvement of NO X removal efficiency. The best injection ratio was the ratio of 6:3:1 (SNCR-1:SNCR-2 (the second row of SNCR):SNCR-3 (the third row of SNCR)), where NO X removal efficiency was 53.10% and NH 3 slip was 8.43 mg/Nm3. [ABSTRACT FROM AUTHOR]

The study of the effect of oxygen carrier content and temperature on chemical looping gasification (CLG) of Chlorella vulgaris was carried out in a fixed bed reactor. In order to obtain the characterization and optimal conditions of CLG for syngas production, this paper analyzed the product fractional yields, gaseous yields, conversion efficiency, SEM, XRD and composition analysis of oxygen carriers. The results indicated that CLG had a greater performance on gasification characteristics. When O/C increased from 0.5 to 3.0, gas yield, CO 2 yield and carbon conversion efficiency increased gradually, but LHV, H 2 and CH 4 yields decreased. Meanwhile, CO yield and gasification efficiency increased firstly and then decreased. Oxygen carrier Fe 2 O 3 exhibited the characteristics of step-wise reduction (Fe 2 O 3 → Fe 3 O 4 → FeO) in CLG process. More FeO were generated at O/C of 0.5 and then caused serious sintering and agglomeration. High temperature was helpful to improve gas yield, carbon conversion efficiency and gasification efficiency. However, higher temperature would cause sintering and then weaken the activity of oxygen carrier. Moreover, under the experimental condition, O/C of 1.0 and 800 °C were the optimal parameters to obtain a high conversion efficiency of biomass, high products yield, good LHV and great reducibility of oxygen carrier. Image 1 • CLG has a greater performance on gasification characteristics than the blank test. • Temperature and oxygen carrier content affect greatly the characteristics of CLG. • Higher temperature will cause sintering and weaken the activity of oxygen carrier. • O/C of 1.0 and 800 °C are the optimal reaction parameters in CLG to produce syngas. • Oxygen carrier exhibits the characteristic of step-wise reduction in the CLG process. [ABSTRACT FROM AUTHOR]

The torrefaction performance and properties of torrefied CS (Camellia shell) bio-char obtained via dry and hydrothermal torrefaction have been compared as well as pyrolysis and combustion properties. And making of torrefied pellets and their properties such as pellet density, Meyer hardness, and energy consumption are also investigated. The results showed that dry torrefied bio-char had higher energy and density at 220 °C and decreased significantly with temperature, while hydrothermally prepared bio-char had stable energy and mass yield with temperature. The coalification status of hydrothermally bio-char is similar to that of sub-bituminous coal. The pellet formed from dry terrified bio-char via quart tube in 220 °C with high pellet density (1048 kg/m 3 ) and low energy consumption (17.6 KJ/kg) in spite of low the Meyer hardness (6.8 N/mm 2 ). As for the process kinetics, the activation energy via dry torrefection with auger showed lower activation energy 43.26 KJ/mol as well as lowest ignition temperature (290 °C), compared to hydrothermal torrefaction. [ABSTRACT FROM AUTHOR]

BTX (benzene, toluene, and xylene) was gained from anisole by gas-phase hydrodeoxygenation (HDO) at ambient pressure with zeolite catalysts. The role of supports such as HBeta, ZSM-5, HY, and γ-Al 2 O 3 was investigated. The effect of temperature and 1/WHSV on the product distribution was also evaluated. The results show that the content of BTX with Fe/Ni/HBeta catalysts, peaked at 24.87%. Fe/Ni/ZSM-5 promoted transalkylation and Fe/Ni/γ-Al 2 O 3 exhibited the lowest anisole conversion of 30%. N 2 -adsorption, XRD and NH 3 -TPD analysis of Fe/Ni/supports suggested that BET surface, pore size, amount and intensity of acid sites significantly influenced products distribution. BTX and phenol were mainly products, indicating that hydrogenolysis focused on C aromatic -OCH 3 and O-CH 3 skeletons, not on π-bone in the anisole ring at ambient pressure. The products such as toluene, xylene, and other multi-methylated aromatics were from transalkylation of benzene and phenol. Fe/Ni supported catalysts were not only beneficial for HDO to remove oxygen but also for transalkylation, mining carbon loss. [ABSTRACT FROM AUTHOR]

Ester products, obtaining from guaiacol and octanoic acid which were the degeneration products of lignin, were tested over sulfonic acid-functionalized SiO 2 materials. The results showed that the functionalized mesoporous SiO 2 had a high activity and stability, resulting in ester yield of 62%. The ratio of S/phenyl played an important role in the activity and stability of SiO 2 -Phenyl-SO 3 H. Moreover, the optimal guaiacol to octanoic acid molar ratio is 8:1. The physicochemical, structural, textural and thermal stability characteristics of the synthesized mesoporous catalysts were investigated by X-ray diffraction (XRD), surface area analysis (Brunauer–Emmett–Teller equation), FT-IR and thermogravimetric analysis (TGA). The result of catalyst characterization and experiment of filtering catalysts from mixture showed that the SO 3 H- group incorporated with functionalized silica precursors. Moreover, the catalytic results indicated that SO 3 H-phenyl- group was the active part and the phenyl group increased the hydrophobicity of the catalyst surface, which accelerated the mobility of water, shifted the equilibrium, protected the acid sites and enhanced the activity of catalysts. [ABSTRACT FROM AUTHOR]

A new improvement of chemical looping gasification (CLG) process is based on microwave pretreatment, which is expected to obtain the kinetics analysis of CLG process for the utilization of microalgae. Thermo-gravimetric characteristics of CLG on Chlorella vulgaris are studied in a thermo-gravimetric analyzer under different heating rates and pretreatment conditions. TG characteristics, weight loss rate, reactivity rate, Homogeneous Model (HM) and Shrinking Core Model (SCM) were investigated in order to study the influence of microwave pretreatment on the CLG kinetics for the utilization of microalgae. The results indicated that microwave pretreatment would improve the TG characteristics and reactivity of microalgae. Moreover, the reactivity rate of CLG increased by 5.77% compared with SiO 2 : Chlorella and it would increase by 6.79% after microwave pretreatment. Furthermore, the higher the heating rate was, the greater the reactivity and weight loss rate of microalgae were. Further, HM could simulate CLG better than SCM. Microwave pretreatment could reduce the activation energy of Chlorella vulgaris and promote CLG. As a result, microwave pretreatment was beneficial to CLG reaction. [ABSTRACT FROM AUTHOR]

To better understand pyrolysis mechanism and further develop selective pyrolysis technology, characteristics of volatile products in the pyrolysis of three main components (cellulose, hemicellulose and lignin) were investigated and compared by amplifying experiments in a tube furnace at 300–700 °C. Distribution of volatile products (including bio-oil and bio-gas), the influence of temperature and contributions of each single component were discussed in depth. It was found that, for each sample pyrolysis, pyrolysis temperature and their own chemical structures played an important role in the yields, composition of bio-oil and bio-gas. The optimal temperatures for production of bio-oil from cellulose, hemicellulose and lignin focused at 500 °C, 450 °C and 600 °C, respectively, and cellulose made greater contribution to bio-oil formation, and hemiellulose was the major contributor for bio-gas. Moreover, the more bio-gases from the three components generated at the higher temperature, but compositions of volatile products were different depending on their unique chemical structures. In the three components, cellulose produced the highest CO, hemicellulose owned the highest CO 2 , and lignin generated the highest CH 4 characterized by the largest HHV. As for bio-oil, cellulose bio-oil displayed unique saccharides and higher furans, hemicellulose bio-oil contained higher acids and ketones, while phenols were the dominant composition of lignin bio-oil. [ABSTRACT FROM AUTHOR]

This study investigated the effects of different pre-treatments on structural changes in Phyllostachys edulis . Samples were pretreated with water, 15% ammonia water, 2% sulfuric acid, hydrothermal carbonization, and ball milling. Moreover, ultrasound was introduced. The influence of pre-treatment on the physiochemical property and composition of P. edulis were studied. Moreover, torrefaction characterization was performed and the distribution of torrefaction products of pretreated samples was determined. Results showed that pre-treatment effectively modified physiochemical structure and the torrefaction property of P. edulis . The pretreatment reduced the ash content and increased the bio-oil content of the torrefaction products. Compared with that of the raw material, the residual bio-char content of the pretreated samples decreased by 2–8%, and degradation temperature of bio-char fluctuated between 365 °C and 321 °C. The distribution of bio-oil contents, bio-char, and bio-gas in the torrefaction products significantly varied with pretreatments methods. [ABSTRACT FROM AUTHOR]

Urban sludge was treated by Hydrothermal carbonization (HTC). The effect of hydrothermal carbonization temperature, mixing with or without catalysts on solid products yield, heavy metal contents, turbidity and COD value was evaluated. The result showed solid products yield decreased from 92.04% to 52.65% when the temperature increased from 180 to 300 °C. And the Cu, Zn, and Pb contents under exchangeable states decreased and reached discharge standard. Addition of FeCl 3 or Al(OH) 3 resulted in a significant increase in the exchangeable states of Zn, Pb, Cr, and Cd and decrease in their residual states. The turbidity and COD value of hydrothermal liquid decreased from 450° to 175°, and 13 to 6.8 g/L, with increasing hydrothermal temperature. Comparison with HTC, solid productivity from low-temperature pyrolysis is higher. The exchangeable states of Cu, Zn, and Cr exceeded the limiting values. Our results show HTC can facilitate transforming urban sludge into no-pollution and energy-rich products. [ABSTRACT FROM AUTHOR]

Biosourced aromatics (benzene–toluene–xylene (BTX) and phenols) could be obtained by catalytic hydrodeoxygenation (HDO) coupled with transmethylation at atmospheric pressure in a fixed-bed reactor. We choose guaiacol as a model compound to investigate the catalytic HDO over Fe/Ni/HBeta catalyst. The active amount (5%–15%), temperature (250–400 °C), and 1/WHSV (1.5–4.0) significantly influenced the hydrogenolysis of the C aromatic O bond and transmethylation. The mechanism showed that feed and intermediate products formed the “surface pool” on the catalyst surface, which enabled the HDO reaction by the reduced intermediate species (Z-FeH 2+ and Z-NiH + ). Fe/Ni/HBeta exhibited good activity for both methyl transfer and HDO. Moreover, the aromatic ring did not undergo catalytic hydrogenation, and most methyl or methoxyl molecules transferred onto the phenolic or benzene ring and remained after deoxygenation. Consequently, carbon loss was minimized, and hydrogen consumption was reduced. [ABSTRACT FROM AUTHOR]

Biomass pyrolysis gas (including H 2 , CO, CH 4 , CO 2 , C 2 H 4 , C 2 H 6 and etc.) reforming for hydrogen production over Ni/Fe/Ce/Al 2 O 3 catalysts was presented in this study. This study investigated how the operating conditions, such as the calcinations temperature of catalysts, the reaction temperature, the gas hourly space velocity (GHSV) and the ratio of H 2 O/C, affect the conversion of CH 4 and CO 2 and the selectivity of hydrogen from dry and steam reforming of pyrolysis gas. The experimental results indicated that, under the conditions: the reaction temperature of 600 °C, the GHSV of 900 h −1 and H 2 O/C of 0.92, the reaction efficiency is the optimal. Especially, the concentration of H 2 , CO, CH 4 , CO 2 , and C 2 H n (C 2 H 4 and C 2 H 6 ) were 36.80%, 10.48%, 9.61%, 42.62%, 0.49% respectively. The conversion of CH 4 and CO 2 reached 45.9% and 51.09%, respectively. There were all kinds of reactions during the processing of reforming of pyrolysis gas. And the main reactions changed with the operation condition. It was due to the promoting or inhibiting interaction among different constituents in the pyrolysis gas and the different activity of catalysts in the different operation condition. [ABSTRACT FROM AUTHOR]

Highlights: [•] Wood vinegar was chosen as the raw material to produce H2. [•] With Ni/γ-Al2O3, H2 yield and concentration can reach 73.94mg/g sample and 69.01%, respectively. [•] With Ni/Ce/γ-Al2O3, carbon deposited decreased from 3.45% to 2.64% and shifted to the lower temperature area. [ABSTRACT FROM AUTHOR]

[Display omitted] • Temperature greatly influences the formation of agglomeration. • Mechanisms, detection methods and countermeasures of agglomeration were reviewed. • The agglomeration mechanism of chemical looping technology was speculated. • The directional design can improve the sintering resistance of OC. • Coating-induced and melt-induced together lead to the ash-related agglomeration. This review discusses the influence of three key factors on agglomeration of chemical looping technology from the aspects of reaction conditions, the oxygen carrier and biomass composition. In addition, the existing agglomeration mechanisms are extended, and the technologies of detection and prevention of the agglomeration is reviewed. In the process of chemical looping reaction, high reaction temperature, the oxygen carrier materials with poor anti-sintering ability and the reaction system containing more alkali metals and silicon-based materials will easily cause agglomeration. Previous literatures have summarized the agglomeration produced by two mechanisms, and both of them pointed out that the alkali metal in the biomass ash is the main component to induce the agglomeration. For the SiO 2 -based oxygen carrier material, it is speculated that the alkali metal will react with the support to inactivate the active metal component through the inclusion of the molten material. However, the oxygen carrier without SiO 2 -based material is mainly produced through the mechanism of melt-induced, but not the coating-induced agglomeration. The predication of agglomeration focuses on the biomass ash test before the reaction and the monitoring of some variables during the reaction process, such as temperature and pressure analysis. Moreover, the agglomeration can be prevented or controlled by condition adjustment, reactor design, oxygen carrier design and biomass pretreatment. In addition, the use of additives is also a reliable method to reduce the agglomeration. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen production from wood vinegar was investigated by catalytic reforming with Ni/M/γ-Al2O3 (M=Co, Cr, Fe) as the catalysts. The maximal H2 yield rate and concentration were 22.03mg/g sample and 64.33% respectively. And the selectivity sequence for hydrogen is Fe, Cr, Co. After catalytic reforming, the content of the compounds was decreased from 16% to 6%. Especially, the content of the acetic acid was decreased from 5.599% to 1.859%, while the content of the phenol was increased from 0.998% to 1.904% due to the demethylation or the demethoxyation of the phenolic compounds. The characteristic analysis showed that the metals of Fe and Ni were the active centers. The amount of carbon deposit was decreased from 5.53% to 2.66%. The distribution of carbon was also shifted to the lower temperature area. [Copyright &y& Elsevier]

• High yield self-N-O doped hydrochar was from microalgae in the aqueous bio-oil. • Hydrochar had a high solid yield (199.33%) and nitrogen content (7.84%). • Amino acids in chlorella, acetol, furfural in bio-oil were main reactants. • Polymer was formed via aldol condensation, esterification and repeated polymerization. • The CO 2 absorption was 5.57 mmol/g and specific capacitance was 216.6F/g (at 0.2 A/g). In this work, the high yield self-N-O doped hydrochar had been prepared through the hydrothermal carbonization of microalgae in the aqueous bio-oil. The effects of temperature, residence time and the ratio of Chlorella and bio-oil on the solid yield were investigated. The results showed that the hydrochar had excellent thermal stability and abundant nitrogen and oxide functional groups, its solid yield reached 199.33%. After activated by KOH at high temperature, the hydrochar was transformed into a porous carbon material with high nitrogen content. The porous carbon showed high CO 2 absorption of 5.57 mmol/g at 0 °C and 1 bar. It also exhibited a high specific capacitance of 216.6F/g at 0.2 A/g and a good electrochemical stability with 88% capacitance retention after consecutive 5000 cycles. [ABSTRACT FROM AUTHOR]

Chemical looping steam methane reforming (CL-SMR) is one of the most potential methods for large-scale syngas production. As the key to CL-SMR, the development of oxygen carrier (OC) is typically limited by the factors of CH 4 conversion, H 2 selectivity and resistance to carbon deposition. However, the nonuniform distribution of metals in OC leads to unstable conversion rate and severe carbon deposition due to metal stacking effects. Therefore, the layer double hydroxides (LDHs) were introduced into OC preparation to achieve uniform metal distribution and solve the above problems. Moreover, different enhanced OCs derived from LDHs precursors were prepared to investigate the effects of divalent metal, Ni/Fe (N/I), Methane/OCs (M/O) and reaction temperature, as well as the adaptability and performance of CL-SMR. The results showed that uniformly dispersed Ni–Fe–Al OC possessed promising CH 4 conversion of 94.32%, H 2 selectivity of 72.61%, CO selectivity of 77.46%, stability of syngas production with H 2 /CO ratio of 2 and low carbon deposition of 5.28%. Further, the increase of N/I from 0.5:2.5 to 2.5:0.5 caused an increase in CH 4 conversion, H 2 selectivity and CO selectivity by 95.04%, 598.82% and 68.19%, respectively. However, the highest N/I ratio led to severe carbon deposition (17.57%) in the Ni 2.5 Fe 0.5 Al OC. Furthermore, Ni–Fe–Al OC with uniformly dispersed active metal exhibited a good stability and suitability in wide-range of M/O and temperature. In addition, H 2 selectivity gradually improved with the increase of M/O, but higher M/O of 1.2 resulted in higher carbon deposition (7.99%). Further, the increase of temperature was beneficial to the OC performance, but excessive temperature (950 °C) led to OC sintering. Moreover, this Ni 2 FeAl OC maintained good catalytic ability and lattice oxygen stability after long-term reaction. [Display omitted] • Metals of LDHs derived oxygen carriers are dispersed at the molecular level. • Molecularly dispersed Ni–Fe–Al oxygen carriers show good CL-SMR performance. • Ni 2 FeAl oxygen carrier shows good suitability in wide-range of M/O and temperature. • Higher N/I ratio can lead to more carbon deposition in the oxygen carriers. • Excessive temperature can lead to severe sintering of the oxygen carrier. [ABSTRACT FROM AUTHOR]

Faced with fossil fuel depletion and increasing environmental concerns, the conversion of renewable biomass into fuels or chemicals is promising but extremely challenging due to the inertness and complexity of biomass. Therefore, in situ multistage condensation combined with the HDO of pyrolysis bio-oil was chosen to reduce the complexity and improve the quality of bio-oil. In addition, the activity and stability of the catalyst was enhanced. The bio-oil obtained via continuous pyrolysis was divided into four-stage depending on their boiling point via in situ multistage condensation. After HDO, the relative content of long-chain alkanes was over 80% for each stage bio-oil via mixed supported Ni/HZSM-5-γ-Al 2 O 3 catalyst. Especially, the main components in the 3rd oil (aqueous phase) were n -heneicosane (31.60%), icosane (5.13%) and n -heptadecane (4.36%) based on the highest HDO ratio. Moreover, the reaction mechanism was discussed via the HDO of model bio-oil. The main reaction pathway consisted of hydrogenation and dehydration reactions (HYD pathway), and a side reaction was the direct deoxygenation route (DDO pathway). This work provides a general and efficient pathway for directly converting biomass into valuable long chain alkanes. Image 1 • HDO upgrading of multistage condensation pyrolysis bio-oil was investigated. • Mixed supports Ni/HZSM-5-γ-Al 2 O 3 showed the outstanding performance for upgrading. • The relative content of long-chain alkanes was over 80% for upgraded bio-oils. • More than 70.1% of HDO ratio of bio-oil after HDO. [ABSTRACT FROM AUTHOR]

Graphical abstract The CS was torrefied under pyrolysis gas from CS continue pyrolysis. And the chemical and physical properties of torrefied char as well as pyrolysis and combustion performance were investigated. Highlights • Torrefaction performance under pyrolysis gas was investigated. • Pyrolysis gas improves the volatile matter content and heat value of torrefied char. • CO 2 , CH 4 and H 2 atmosphere changes the structure of cellulose and lignin. • Each composition in PG play synergy role on the severity of torrefied char. • Torrefied char under pyrolysis gas shows a better combustion performance. Abstract In order to complete using the pyrolysis gas and heat from biomass routine pyrolysis, the camellia shell was torrefied under PG atmosphere. And the chemical and physical properties of torrefied char obtained under N 2 and pyrolysis gas were compared as well as the pyrolysis and combustion performance. Moreover, in order to investigate the mechanism of pyrolysis gas torrefaction, the influence of each composition such as H 2 , CO 2 and CH 4 in pyrolysis gas on the torrefaction performance was also been studied. The results show pyrolysis gas improves the volatile matter content and heat value of the torrefied char. Moreover, pyrolysis gas promotes the degradation of cellulose and hemicellulose. Chemical structure is different for torrefied char under pyrolysis gas and N 2 atmosphere. And each composition in pyrolysis gas plays synergy role to the severity of torrefied char. The combustion kinetic of torrefied char were calculated using the Friedman method and the Ozawa-Flynn-Wall method. [ABSTRACT FROM AUTHOR]

Pyrolysis, one of the most promising thermal conversion technologies for biomass conversion, can decompose biomass into solid bio-char, liquid bio-oil, and combustible gas to meet different energy needs. However, pyrolysis efficiency and product quality are not as good as expected when raw biomass is used owing to the properties of raw biomass (e.g., high moisture, oxygen, and alkali metal contents). Torrefaction is an emerging biomass pretreatment technology that can improve the physical and chemical properties of raw biomass, and pyrolysis efficiency and final product quality can therefore be improved by using torrefied biomass. We review several advantages of pyrolysis of torrefied biomass in terms of the conversion process and final product quality. Highlights The torrefaction process changes the pyrolysis characteristics of biomass, including the reaction process, kinetic parameters, and product distribution and properties. Torrefaction affects the ratio and chemical composition of pyrolysis products, improves the product quality and conversion process, and increases conversion efficiency during the pyrolysis process. Most torrefied biomass pyrolysis research has been conducted in laboratory-scale fixed beds at a relatively low temperature, and continuous reactors still need to be investigated and pilot-scale studies need to be performed. Catalytic pyrolysis of torrefied biomass is a promising technology to convert biomass into useful chemicals. [ABSTRACT FROM AUTHOR]

Chemical-looping gasification (CLG) of Chlorella vulgaris was carried out in a quartz tube reactor under different microwave pretreatment. The product fractional yields, conversion efficiency and analysis of performance parameters were analyzed in order to obtain the characterization and optimal conditions of microwave pretreatment for syngas production. The results indicate that microwave pretreatment is conducive to CLG reaction. Furthermore, the higher power or the longer time in the process of microwave pretreatment could not exhibit a better effect on CLG. In addition, 750 W and 60 s is the optimal microwave pretreatment power and time respectively to obtain a great reducibility of oxygen carrier, high conversion efficiency, high products yield and good LHV. The H 2 yield, LHV, gasification efficiency and gas yield increased obviously from 18.12%, 12.14 MJ/Nm 3 , 59.76% and 1.04 Nm 3 /kg of untreated Chlorella vulgaris to 24.55%, 13.13 MJ/Nm 3 , 72.16% and 1.16 Nm 3 /kg of the optimal microwave pretreatment condition, respectively. [ABSTRACT FROM AUTHOR]

Bio-char is a promising carrier for the catalysts applied in hydrodeoxygenation (HDO) of bio-oil. The impact of bio-char surface microenvironment on the active phase needs to be further explored. In this work, O-containing functional groups were employed in adjusting the surface microenvironment of biomass-derived char with Ni–Mo loading. And the effect of geometric structure and electronic modification of Ni/MoOx-Ov interface on the atmospheric HDO activity of guaiacol over Ni-MoOx/bio-char catalyst was studied. Multiple characterizations revealed that the O-containing functional groups on bio-char carriers not only promoted the dispersion of active metals, but also decreased the particle size, thus resulting in the boosting of Ni/MoOx-Ov interface. Moreover, the intrinsic active sites were sumi-quantitatively analyzed via H 2 -TPD, and a positive correlation was established between BTX yield and quantity of Ni/MoOx-Ov interface. Furthermore, the effects of hydrothermal parameters for preparing bio-char, HDO conditions (temperature, WHSV and stability) and the metal loadings on the catalytic performance of Ni-MoOx/bio-char catalysts were studied in detail. This work provides a theoretical support to develop cost-effective catalysts with the utilization of biomass waste material. Synopsis: In this work, the effect of the surface microenvironment of bio-char carriers modified by functional groups on the catalytic activity of bio-char based catalyst loading Ni–Mo to convert bio-guaiacol (biomass tar simulant) to BTX was investigated. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Agglomeration is affected by OC preparation of methods, carriers and Al:Fe ratios. • Co-precipitation method has better dispersion and lower agglomeration degree. • The carrier plays a role in dispersing active metals and supporting the OC structure. • Fe content will influence the active sites and the metal-carrier interaction. • Excessive Fe content causes serious agglomeration and lower performance. Iron-based oxygen carrier (OC) plays a crucial role in biomass chemical looping gasification (BCLG) to produce high quality syngas. However, a significant challenge during BCLG is the OC deactivation due to agglomeration, which is an urgent problem to be solved. In this study, the agglomeration behavior of iron-based OC preparation during the application for BCLG was obtained under the investigation of different preparation methods, carriers and ratios of active metal to carrier. The results revealed that preparation method affected the dispersion, crystal structure and stability of OC, thereby affecting the agglomeration. Among four preparation methods, the OC prepared by co-precipitation method achieved a 58.57 % lower agglomeration degree and 38.38 % smaller particle size than that of mechanical mixing method. Moreover, the carrier played a role in structural support and lattice oxygen transport, affecting crystalline structure and the agglomeration. Among four carriers, the OC prepared with Al 2 O 3 carrier exhibited 36.18 % lower agglomeration degree and 25.15 % smaller particle size than that of CeO 2 carrier. In addition, higher Fe content would weaken the metal-carrier interaction and reduce the structural stability of OC, causing serious agglomeration. With the decrease of Al:Fe molar ratio, the average particle size and agglomeration degree of spent OC increased by 43.56 % and 78.26 %, respectively. With the increase of cycles, the average particle size and agglomeration degree of spent OC increased gradually, while the reaction performance decreased obviously. [ABSTRACT FROM AUTHOR]

The utilization of CO 2 has attracted lots of attentions, while the conversion and utilization of common low concentration carbon dioxide has not been widely concerned. Herein, oxygen-free low concentration(<40%) CO 2 mixed gas has been explore in the utilization of methane reforming. the low concentration CO 2 mixed gas, which derived from biomass gasification, combined steam reforming methane route has been proposed and explored in the study. The effect of each key parameters, including CO 2 mixed gas addition, reaction temperature, S/C and WHSV, on the syngas yield were investigated.In the proper condition, an product with H 2 /CO ratio around 2 and 97% syngas purity was obtained. Furthermore, since the Ni-modified volcanic rock catalyst showed excellent activity in the reforming reaction, its stability was further confirmed via life test, meanwhile, the other characterizations were observed via XRD, SEM,TEM and BET. the results showed that the catalyst was stable after 24h life experiment with less than 0.15% carbon deposited. Moreover, TEM results revealed that Na and Fe existed in the volcanic rock would gradually migrated to the Ni particle during the reaction, which should be the main mechanism for the improvement of activities and stability of the catalysts. The study provide a new way to utilized the low concentration CO 2 mixed gas. Biomass Derived low concentration CO 2 mixed Gas Combined Steam to Reform Methane through Ni Based Volcanic Rock Catalyst. [Display omitted] • Low concentration CO 2 showed excellent potential in methane reforming. • The content of synthesis gas in reforming products could reach 97%. • Ni/VR catalyst was stable after 24h reaction with less 0.15% carbon deposition. • The Na and Fe element in VR enhanced the activities and stability of catalyst. [ABSTRACT FROM AUTHOR]

Swine manure activated carbon (SMAC) was prepared by a simple in situ template method combining KOH activation with pyrolysis and using swine manure (SM) as a precursor. Natural metal oxides in SM are fully utilized as in situ templates instead of being removed. The effects of the in situ templates and the structural characteristics of the SMACs were studied via three contrasting strategies involving different pickling steps during pyrolysis and activation. The SMACs show excellent structural properties with specific surface areas of 876–2321 m2/g. The micropores size of all SMACs are concentrated at 0.5–0.6 nm; SMAC PHF has the most macropores (∼50 nm), and SMAC HF has more large macropores (∼100 nm) and mesopores (2–4 nm). These results should be attributed to CaO acting as a pore support, MgO catalyzing carbon decomposition and SiO 2 reaction promoting the activation effect. SMAC HF shows the best electrochemical performance with a specific capacitance of 278 F/g at 0.5 A/g and a high energy density of 24.62 Wh/kg at 450 W/kg for SMAC HF -based symmetric supercapacitors; the rate of retention is 96.2% after 10,000 cycles. This study provides a meaningful scheme for the low-cost and effective preparation of biomass carbon electrodes for supercapacitors. [Display omitted] • Swine manure activated carbon was prepared by an in situ template method. • Templates promoted activation and pore development. • Removing templates at different stages had distinct effects on the structure. • SMAC HF exhibited the largest SSA of 2321 m2/g. • At 0.5 A/g, SMAC HF had a maximum SC of 278 F/g with a 6 M KOH electrolyte. [ABSTRACT FROM AUTHOR]

Chemical looping steam methane reforming (CL-SMR) is a promising and efficient method to produce hydrogen and syngas. However, oxygen carrier (OC) prepared by synthesis are complex, expensive and poor mechanical performance, while natural ore OCs are low activity and poor selectivity. In order to avoid these problems, Ni/Fe modification of natural ores were proposed to improve the reactivity and stability of OC to CL-SMR. The results indicated that the modified calcite recombined and improved the structural phase during the reaction, enhancing performance and inhibiting agglomeration. Moreover, high ratio of iron to nickel was easy to sinter and decline the OC performance. In addition, with the increase of steam flow, both CH 4 conversion and carbon deposition decreased. Thereinto, the highest H 2 concentration, CH 4 conversion efficiency and H 2 yield were obtained when the ratio of steam to OC was 0.05. Furthermore, CH 4 flow rate had a great impact on CL-SMR performance. When the ratio of CH 4 to OC was 0.04, it achieved the highest CH 4 conversion efficiency of 98.96%, the highest H 2 concentration of 98.83% and the lowest carbon deposition of 3.23%. However, the carbon deposition increased with the increase of CH 4 flow rate. After a long-time chemical looping process, the Ni/Fe modified calcite showed a consistently stable performance with average H 2 concentration of 93.08%, CH 4 conversion efficiency of 88.03%, and carbon deposition of 2.15%. • Natural ores show good performance of oxygen carrier in chemical looping reforming. • High Iron/Nickel is easy to sinter and decline the OC performance. • Steam and CH 4 content have an obvious effect on H 2 production and efficiencies. • Ni/Fe improves the abilities of anti-agglomeration and anti-sintering of calcite. • Ni/Fe modified calcite exhibits an excellent stability performance to produce H 2. [ABSTRACT FROM AUTHOR]

The subject of this study was to upgrade the pyrolysis bio-oil by torrefaction combined with different order of acid washing. The pyrolysis behavior of biochar obtained from different pretreatments were investigated by a thermogravimetric analyzer (TGA) and fixed furnace. Moreover, the composition of bio-oil was systematically analyzed by GC-MS. The results showed that torrefaction promoted the aggregation of phenols in bio-oil through removing the hemicellulose and part of cellulose. In addition, aldehydes had increased significantly after acid washing. The acid washing combined with torrefaction could reduce the formation of acids, alcohols and other organic substances except for phenols, aldehydes and ketones. Compared with the pyrolysis bio-oil obtained by directly torrefaction pretreatment, the absolute content of phenols in the pyrolysis bio-oil was slightly reduced from 74 mg/gRH to 63 mg/gRH after first inorganic acid washing and then torrefaction, while the absolute content of furfural increased from 2.8 mg/gRH to 16 mg/gRH. The mechanism showed that the furfural was selected by the catalysis of acid and the torrefaction promoted the cellulose to convert to 1-hydroxy-2-propanone by cracking reaction. This study provided a simple and practical method for the selective production of furfural and phenol from rice husk. Image 1 • The furfural and phenols were selectively produced by synergistic pretreatment. • The optimal results were obtained by inorganic acid washing and then torrefaction. • Ultrasounds promoted the catalysis of acid on polycondensed of furfural. • Aldehydes increased from 15% to 25% by inorganic acid washing and then torrefaction. [ABSTRACT FROM AUTHOR]

The separation of CO 2 from the nature gas is a challenge for solid sorbents. Bio-tar, a low cost and renewable carbon source, is employed to synthesis the ultra-microporous carbon materials. Carbonization of bio-tar with potassium hydroxide (KOH) at high temperatures (>700 °C) yields porous carbon materials with high surface areas of up to 2595 m2 g−1 and high CO 2 uptake performance of 5.35 mmol g−1 at 1 bar and 0 °C. This carbon material also shows good CO 2 /CH 4 selectivity in mixed gas and excellent cyclability. In gas breakthrough test, the retention time of bio-tar-derived carbon for carbon dioxide and methane adsorption is 849 s g−1 and 337 s g−1, respectively. The retention time of CO 2 is 157 s g−1 at 150 °C while CH 4 is nearly non-adsorption. The carbon material has good cycle performance for carbon dioxide adsorption. Molecular simulations suggest that CO 2 density in micro and narrow mesopores will be increased at high pressures. This is consistent with the observation that these pores are mainly responsible for the material's high-pressure CO 2 capacity. This study provides insights in designing of bio-tar material and further developing for CO 2 capture from natural gas. CO 2 emissions will have a significant impact on the environment and climate. In particular, natural gas as a clean energy source has broad application. But CO 2 with a content of 2%-10% in natural gas will cause a large amount of CO 2 emissions when applied, and reduce the quality of natural gas. Therefore, it is extremely important to develop inexpensive CO2 capture agents. In this study, bio-tar, a hazardous waste, is employed to prepare self-doped nitrogen porous carbon materials with ultra-high specific surface area, showing excellent CO 2 capture performance and the ability to separate CO2 from CH4. Under high temperature conditions, it still retains a strong adsorption capacity for carbon dioxide. The DFT calculation shows that the material exhibits the best adsorption performance when the specific surface area is 2600 m2/g, which provides a guiding role in the synthesis of the bio-tar-derived carbon material. Image 1 • Synthesis of self-doped nitrogen porous carbon material using bio-tar as material. • The maximum value of CO 2 -adsorption is 5.35 mmol/g at 273 K. • Gas breakthrough tests is employed to study the capture ability for separating CO 2. • Good thermal stability enables recycling of the porous carbon sorbent. [ABSTRACT FROM AUTHOR]

• HY zeolite is the best carrier to convert wood vinegar into H 2 -rich syngas by CLR. • Ni/HY has excellent redox performance and gasification efficiency during CLR. • The optimal Ni loading is 20% with the highest H 2 yield and gasification efficiency. • +15% is the best water volume for CLR on crude wood vinegar. • Carbon deposition of Ni/HY at 900 °C for long-time reaction is the lowest. The crude wood vinegar contained a large amount of water and a small amount of complex organic compounds, which was difficult to industrialize practically. An efficient oxygen carrier was prepared by Ni-modified HY zeolite (Ni/HY) to produce hydrogen-rich syngas by chemical looping reforming (CLR) on crude wood vinegar. The yield of gas, conversion efficiency, H 2 /CO, oxygen carrier structure and carbon deposition were investigated to obtain the optimal preparation of oxygen carrier and the optimal CLR performance. The results showed that HY zeolite was the most suitable carrier for CLR among five different molecular sieves. Compared with HY zeolites modified by different metallic oxides, Ni/HY had the highest H 2 yield of 64.68%, gasification efficiency of 85.29% and structural characteristics. Further, water volume had a great impact on the CLR performance. The optimal water volume was + 15% with H 2 yield of 68.4%, carbon conversion efficiency of 37.58% and gasification efficiency of 92.38%. Furthermore, the particle size of oxygen carrier increased with the increase of Ni loading. The best performance with gasification efficiency of 96.17% and carbon conversion efficiency of 39.41% could be obtained when the Ni loading was 20%. Moreover, the CO yield, gasification efficiency and carbon conversion efficiency gradually increased with temperature increasing. After CLR for the long-term reaction time, 900 °C was the best reaction temperature to achieve gasification efficiency of 107.29% and the lowest carbon deposition of 3.71%. [ABSTRACT FROM AUTHOR]

The chemical looping gasification (CLG) of rice husk was conducted in a small fixed-bed reactor to investigate the effects of oxygen carrier preparation methods, active components, Fe loadings, water inflow and successive redox cycles. The gas content, the relative gas concentration, lower heating value of syngas (LHV), carbon conversion efficiency, gasification efficiency, H 2 -TPR, XRD, BET and SEM were analyzed to obtain CLG reaction characterization and comprehensive performance of oxygen carrier. The results showed that compared with several methods and active components, the coprecipitation method with a Fe:Al ratio of 2 was the best preparation method for oxygen carrier. Furthermore, the H 2 concentration was 57.29%, while the gasification efficiency and carbon conversion efficiency were 95.79% and 51.56%. Meanwhile, the oxygen carrier prepared by coprecipitation had a greater performance of oxygen release and reduction. There was an optimal water inflow to obtain the highest gas content, carbon conversion efficiency and gasification efficiency. Thereinto, the H 2 concentration was stable at 54.07–57.65%. And the highest gas content of 78.33% and carbon conversion efficiency of 54.42% were obtained at a water inflow of 14.0 mL/h, while the highest gasification efficiency of 95.79% was obtained at 16.8 mL/h. In addition, after ten successive redox cycles, the gasification performance, crystal size, specific surface area and pore structure were relatively stable. Moreover, the material composition remained basically unchanged. • Coprecipitation is the best preparation method to gain the highest H 2 concentration. • Fe is the optimal active component to gain a highest H 2 concentration and efficiency. • Al:Fe of 2:1 is the best Fe loading in oxygen carrier for a great performance. • Water inflow is beneficial to increase the H 2 concentration. • Reaction performance and structure are stable after ten successive redox cycles. [ABSTRACT FROM AUTHOR]

Hydrodeoxygenation (HDO) is considered as one of the most promising routes to upgrade bio-oil for high value-added chemicals. In the study, the gas-phase HDO of guaiacol in atmosphere and 350 °C over Ni-based catalysts modified by Fe, Ga, Ce, La, or Sm on HUSY zeolite support was carried on. The effect of promotors, bimetallic/monometallic catalysts and Ni loading on HDO activity was investigated. The results showed that phenols and aromatic hydrocarbon were the main products and Ni was the main metal active site. Compared with monometallic metal catalysts, the promoters, such as Fe, Ga, Ce, La, and Sm, inhibited the aggregation of Ni, promoted Ni dispersion, and improved the HDO activity of guaiacol significantly. The highest conversion of 98.36% was performed over 10%Sm-20%Ni/HUSY, and the highest degree of hydrodeoxygenation (HDO%) of 7.7% was obtained over 10%La–20%Ni/HUSY catalysts. For Ce, Ga, and Fe modified catalysts, hydroquinone selectivity was higher than that over La and Sm modified catalysts. However, for La and Sm modified catalysts, phenols selectivity increased, and more aromatic hydrocarbon was formed. The HDO activity was improved via increasing Ni loading. Direct deoxygenation and hydrogenation were the more reasonable reaction pathways for gas phase guaiacol atmospheric HDO over Ni-based bimetallic HUSY catalysts. Image 1 • Atmospheric hydrodeoxygenation of guaiacol over Ni based bimetallic HUSY catalysts. • The roles of different promoters including Fe, Ga, Ce, La, Sm were investigated. • The improved HDO activity was due to better Ni dispersion promoted by Sm and La. • The increase of Ni loading improved the aromatic hydrocarbon content in products. [ABSTRACT FROM AUTHOR]

In chemical looping gasification (CLG), as one of the most commonly used oxygen carrier (OC), agglomeration is one of the most crucial triggers of Fe 2 O 3 /Al 2 O 3 OC deactivation. However, the formation mechanism of agglomeration is not clear due to the complexity of the interaction between biomass and OC. In this study, we investigated agglomeration process of Fe 2 O 3 /Al 2 O 3 OC in CLG from two dimensions of time and space. The results showed that in the time dimension, after ten cycles, the DT (deformation temperature) of the spent OC decreased by 5.39%, showing melting point was lower after cycles. Meanwhile, it caused the significant increase of the average particle size (59.73%) and the agglomeration degree (120.13%), indicating more severe agglomeration. Further, it led an obvious decrease in the CLG performance of efficiencies and gas yield. In the space dimension, when agglomeration occurred, low melting point K and Na compounds would first melt on the OC surface to form the K–Na inner layer (KAlSi 2 O 6 and NaAlSiO 4). As the reaction continued, high melting point Ca and Mg compounds would also be adhered to the surface of inner layer to form the Ca–Mg outer layer (CaAl 2 Si 2 O 8 and Mg 4 Al 10 Si 2 O 23), resulting in the continuous increase of OC particle size. In addition, more molten substances of KAlSi 2 O 6 and NaAlSiO 4 would lead to more adhesion between the OC particles. [Display omitted] • The molten layer on the OC surface thickened as the number of cycles increased. • The agglomeration of OC could be divided into the inner and outer layer. • K and Na compounds would first melt on the OC surface to form the K–Na inner layer. • Ca and Mg compounds would be adhered to form the Ca–Mg outer layer. • More molten substances would lead to more adhesion between the OC particles. [ABSTRACT FROM AUTHOR]

Molten salt hydrate (MSH) is unique in cellulose dissolution and in one-pot conversion of crystalline cellulose into 5-hydroxymethylfurfural (5-HMF). However, low yield of 5-HMF was obtained using raw biomass substrate in MSHs. Herein, we investigated conversion of raw biomass towards HMF using MSHs. We showed that the release of acetic acid from hemicellulose degradation in MSH is a key to influence the yield of 5-HMF. Thus, an autohydrolysis pretreatment method was proposed to remove hemicellulose before conversion of cellulose into 5-HMF. After being pretreated at 180 °C for 40 min, hemicellulose was removed from biomass with 91.8% yield of cellulose remained in solid part. By eliminating the negative effect of acetic acid, 5-HMF yield was significantly improved from 40.9% to 64.6%, together with 9.3% yield of glucose for cellulose conversion in MSH/acetone at 180 °C for 20 min. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Surfactant promoted HTC performance and pseudo lignin formation. • Surfactant improved solid products, heat value, HBO, H 2 and CO content. • SDBS promoted the BET surface of hydrochar increased from 4.93 to 41.43 m2/g. • Surfactant promoted HBO/water film formation for polymerization of 5-HMF with HMF. • Absorbed HBO and formed pseudo lignin improve SN and decrease Tf of solid products. Abstract The effect of surfactant on the hydrothermal carbonization performance and pseudo-lignin formation were investigated. Especially, the fuel properties and combustion characteristics of hydrochar and solid product were determined. Furthermore, the mechanism of surfactant acted in hydrothermal carbonization was also identified in this article. The results showed that surfactant improved the content of solid products, lignin, heavy bio-oil (HBO), H 2 and CO. Moreover, sodium dodecylbenzenesulfonate promoted the increase of the surface area of hydrochar from 4.93 to 41.43 m2/g. The mechanism showed surfactant formed water/oil film around the hydrochar to prevent HBO from leaving the pore or surface of hydrochar and promoted the condensation and polymerization of 5-hydroxymethylfurfura (5-HMF) with hydroxymethylfurfura (HMF) to form pseudo-lignin. The HBO and pseudo-lignin were beneficial for improving integrated combustion characteristic index (SN) during combustion. The article provides a new method to promote hydrothermal carbonization (HTC) for obtaining high value hydrochar as fuels. [ABSTRACT FROM AUTHOR]