Abstract: Fischer-Tropsch synthesis is one of the core processes for producing aviation fuel from biomass gasification. However, the products of Fischer-Tropsch synthesis have a high content of normal alkanes and poor low-temperature fluidity, which need to be converted into low freezing point jet fuel through the hydroisomerization dewaxing process. In this study, the fraction of the Fischer-Tropsch synthesis products that meets the distillation range requirements of jet fuel was used as the raw material, and a molecular sieve-based hydroisomerization dewaxing catalyst was adopted to systematically study the reaction path of alkane hydroisomerization dewaxing. The results show that, at the same conversion depth, the isomerized alkane yield of the Pt/ZSM-48 catalyst is significantly better than that of the Pt/ZSM-22, especially in the generation of multi-branch isomerized alkanes. At low conversion rates, the Pt/ZSM-48 is more inclined to produce middle single-methyl branched alkane products, indicating that it mainly undergoes the key-lock catalytic mechanism. Meanwhile, compared with the Pt/ZSM-22 catalyst, the molar conversion rate of C₁₄+ alkanes on the Pt/ZSM-48 is higher, indicating that it is more conducive to the conversion of high-carbon normal alkanes into multi-branch isomerized alkanes and promotes the cracking reaction near the middle of the molecular chain. When using the Pt/ZSM-48 catalyst at a conversion rate of 3.81%, the yield of jet fuel fractions reached 98.18%, and the properties of the products, such as freezing point and density, all met the jet fuel standards, providing technical support for the efficient preparation of biomass aviation fuel.

Key words: Fischer-Tropsch synthetic oil, hydroisomerization dewaxing, reaction pathway, low freezing point jet fuel