Shaolong Wan

A review on ex situ catalytic fast pyrolysis of biomass

Catalytic fast pyrolysis (CFP) is deemed as the most promising way to convert biomass to transportation fuels or value added chemicals. Most works in literature so far have focused on the in situ CFP where the catalysts are packed or co-fed with the feedstock in the pyrolysis reactor. However, the ex situ CFP with catalysts separated from the pyrolyzer has attracted more and more attentions due to its unique advantages of individually optimizing the pyrolysis conditions and catalyst performances. This review compares the differences between the in situ and ex situ CFP operation, and summarizes the development and progress of ex situ CFP applications, including the rationale and performances of different catalysts, and the choices of suitable ex situ reactor systems. Due to the complex composition of bio-oil, no single approach was believed to be able to solve the problems completely among all those existing technologies. With the increased understanding of catalyst performances and reaction process, the recent trend toward an integration of biomass or bio-oil fractionation with subsequent thermo/biochemical conversion routes is also discussed.

Direct Coupling of Thermo‐ and Photocatalysis for Conversion of CO2–H2O into Fuels

Photocatalytic CO2 reduction into renewable hydrocarbon solar fuels is considered as a promising strategy to simultaneously address global energy and environmental issues. This study focused on the direct coupling of photocatalytic water splitting and thermocatalytic hydrogenation of CO2 in the conversion of CO2 -H2 O into fuels. Specifically, it was found that direct coupling of thermo- and photocatalysis over Au-Ru/TiO2 leads to activity 15 times higher (T=358 K; ca. 99 % CH4 selectivity) in the conversion of CO2 -H2 O into fuels than that of photocatalytic water splitting. This is ascribed to the promoting effect of thermocatalytic hydrogenation of CO2 by hydrogen atoms generated in situ by photocatalytic water splitting.

A Strategy for the Simultaneous Synthesis of Methallyl Alcohol and Diethyl Acetal with Sn-β

A new strategy was developed to simultaneously produce two important chemicals, namely, methallyl alcohol (Mol) and diethyl acetal (Dal) from methacrolein in ethanol solvent at low temperature with the use of Beta zeolites modified by tin (Sn-β catalysts). All the Sn-β catalysts were prepared by the solid-state ion-exchange method, wherein the calcination step was conducted under different gas atmospheres. The catalyst precalcined in Ar (Sn-β-Ar) had a reduced number of extra-framework Sn species and enabled more Sn species to be exchanged into the framework as isolated tetrahedral SnIV , enhancing the catalytic activity of the Meerwein-Ponndorf-Verley (MPV) reaction. The sodium-exchanged Sn-β-Ar, with a reduced number of weak Brønsted acid sites, led to an even better selectivity for Mol, owing to the restriction of the side reactions such as acetalization, addition, and etherification. Under optimized catalyst and reaction conditions, the yield of Mol and Dal reached approximately 90 % and 96 %, respectively. The possible reaction pathways, along with a complex network of side products, was proposed after a detailed investigation through the use of different substrates as reactants. The fine-tuning of Sn-β catalysts through different treatments discussed in this work is of great significance toward the understanding and manipulation of complex reactions between α,β-unsaturated aldehydes and primary alcohols.