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Catalytic liquefaction can effectively convert solid biomass into liquid bio-crude that could be upgraded to advanced biofuel, but the exploration of green and efficient catalysts remain a challenge. In this study, bifunctional Zn/HZSM-5 catalysts were firstly combined with supercritical ethanol to produce bio-crude in pine sawdust catalytic liquefaction. The catalysts were characterized by BET, NH 3 -TPD, XRD and TEM. The effects of Zn/HZSM-5 catalysts with different Zn loading ratios on the yield and quality of bio-crude and gas were investigated. The results showed that Zn/HZSM-5 and HZSM-5 catalysts improved the yields of bio-crude compared to no catalyst treatment. The use of HZSM-5 based catalysts reduced the contents of oxygenated compounds including acids, ketones, phenols and alcohols in bio-crude products. Hydrocarbons content of the bio-crudes produced by HZSM-5 based catalysts increased compared to bio-crude produced by no catalyst treatment. Compared to HZSM-5 catalyst, Zn/HZSM-5 catalysts exhibited better catalyst performance to improve bio-crude quality due to the additional decarbonylation, decarboxylation and dehydrogenation reactions induced by Zn loading. 15%Zn/HZSM-5 catalyst resulted in the highest yields of bio-crude at 59.09 wt.%, and 10%Zn/HZSM-5 catalyst produced bio-crude with the highest hydrocarbons content at 15.03%. The four stages of mechanism for biomass liquefaction reactions on Zn/HZSM-5 catalysts in supercritical ethanol was proposed. [ABSTRACT FROM AUTHOR]

In this study, the pine sawdust thermal conversions over HZSM-5 catalyst were carried out under different reaction temperatures in a two-stage catalytic pyrolysis reactor. Higher temperatures in the catalytic reactor tended to decrease the yield of bio-oil and change the component of bio-oil. The results from the gas chromatography–mass spectrometry (GC–MS) analysis showed that the pyrolysis reaction at 500 °C and catalytic reaction at 500 °C treatment obtained the highest hydrocarbon content (58.63%) and the highest C 8 –C 12 content (48.03%) in the oil phase of the bio-oil. The X-ray diffraction (XRD) and selected-area-electron-diffraction (SEAD) characterization showed that the distortion of the ZSM-5 zeolite lattice occurred before and after use. The Brunauer–Emmett–Teller (BET) characterization indicated that the formation of coke increased as the catalytic temperature rose. The physical characterization of bio-oils, such as water content, density, viscosity, pH, and higher heating value (HHV) further demonstrated that HZSM-5 catalyst was beneficial in achieving low viscosity and higher HHV bio-oils. All the results suggest that the two-stage catalytic pyrolysis reactor with HZSM-5 catalyst has a great potential for achieving advanced biofuel. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated microwave pyrolysis of prairie cordgrass (PCG) to determine the effects of pyrolysis temperature and time on the yields of bio-oil, syngas, and biochar. Microwave pyrolysis of PCG was analyzed using response surface methodology (RSM) to find out the effect of process variables on the bio-oil and syngas yield and established prediction models. Second-order reaction kinetics was developed to model the PCG pyrolysis. Bio-oil recovery was in the range of 20.3–33.1wt% of the biomass. GC–MS analysis indicates that the bio-oil contained a series of important and useful chemical compounds: aliphatic hydrocarbons and aromatic hydrocarbons. These chemical compounds evolved were related to the pyrolysis conditions. [Copyright &y& Elsevier]

Highlights: [•] The first study of integrated microwave torrefaction and pyrolysis of corn stover. [•] Microwave torrefied pyrolysis favored phenols and hydrocarbons production. [•] Organic acids were significantly reduced in bio-oils. [•] Up to 26.7 area% hydrocarbons in the bio-oil were produced. [ABSTRACT FROM AUTHOR]

Abstract: Microwave pyrolysis of Douglas fir sawdust pellet was investigated to determine the effects of reaction temperature and time on the yields of bio-oil, syngas, and charcoal using a central composite design (CCD) and response surface analysis. The research results indicated that thermo-chemical conversion reactions can take place rapidly in large-sized biomass pellet by using microwave pyrolysis. The yields of bio-oil and syngas were increased with the reaction temperature and time. The highest yield of bio-oils was 57.8% (dry biomass basis) obtained at 471°C and 15min. GC/MS analysis indicated that the bio-oils were mainly composed of phenols, guaiacols, furans, ketones/aldehydes, and organic acids. The yield of specific chemicals such as furans and phenolic compounds were highly related to the reaction temperature. The syngas contained high value chemicals, such as carbon monoxide, methane, and short chain hydrocarbons. A third-order reaction mechanism fits well the microwave pyrolysis of Douglas fir pellet with activation energy of 33.5kJ/mol and a frequency factor of 3.03s−1. [Copyright &y& Elsevier]