Direct conversion of sawdust into biobased aviation fuel precursor via atmospheric catalytic hydropyrolysis process

This research aimed to develop catalyst and technology design to selectively convert sawdust into bio jet fuel (BJF) components via ex-situ catalytic hydropyrolysis (CHP) process. Design of catalyst configuration was carried out considering the fact that an efficient catalyst for biomass pyrolysis process requires (i) an improved diffusion rate of reactants/products to and from the catalyst active sites, (ii) suppression of secondary reactions, and (iii) prevention of deactivation mechanisms. Hence, sawdust was hydropyrolyzed in a customized continuous pyrolysis system and then the pyrolysis vapors were upgraded while passing through a bed of a well-designed guard catalyst (CatG) followed sequentially by a suitable hydroconversion catalyst (CatH). The morphology and chemical structure of CatG and CatH were synergistically designed to enhance the selectivity towards aromatic hydrocarbons in the range of jet fuel chemicals for 75 %. Effects of different process parameters, such as structure and morphology of CatG, catalyst upgrading temperature (350 and 400 °C), pyrolysis gas environment (N 2 , H 2 /N 2 , and air/N 2 ), concentration of CatG active sites (8, 17, 33, and 50 wt%), and durability of catalysts, on the process efficiency concerning reaction selectivity towards BJFs, heating value of the pyrolysis products, and carbon efficiency of the whole process were investigated. Specifically, the durability of combined catalysts was evaluated for four times and the results showed that the catalysts combination resulted in similar selectivity to BJFs during recycling tests. The maximum selectivity to BJFs (42 %) was achieved at 400 °C, WHSV 3 h −1 , reaction time 3 h, carrier gas H 2 /N 2 , and CatG 33 wt%. • Atmospheric catalytic hydropyrolysis (CHP) of sawdust into bio jet fuel (BJF). • Multi-functional catalysis using guard and hydroconversion catalysts. • Zeolite desilication to a well-designed porous guard catalyst with mild acidity. • One-step pyrolysis-upgrading to an oil with 42 % BJF selectivity and 30.2 kJ/kg HHV. • Stable catalytic performance in CHP of sawdust into BJF via several recycling tests.