Design of hierarchically structured cubic Fe-based catalysts with controllable assembly architectures for gasoline fuel synthesis

Abstract

The direct conversion of syngas into gasoline-range fuels (C₅–C₁₁ hydrocarbons) using a metal–zeolite bifunctional catalyst is an effective approach for Fischer–Tropsch Synthesis (FTS). However, it remains a significant challenge to achieve a gasoline product fraction with excellent selectivity and good stability. In this study, hierarchical porous catalysts with controllable assembly architectures were designed by adjusting the hydrothermal temperature. These catalysts were then physically mixed with zeolite to fabricate bifunctional catalysts. The characteristics and catalytic performance of the bifunctional catalysts were evaluated for the one-step conversion of syngas to C₅–C₁₁ hydrocarbons. It was found that the dense assembly structure of FeZ-120 inhibits the interaction between syngas and active sites, thereby leading to lower CO conversion. FeZ-200 exhibits a looser assembly structure, which is not conducive to the uniform diffusion of syngas and FTS products, resulting in poor catalytic stability. Furthermore, FeZ-160 with a regular assembly structure exhibits a lower content of the CFe2.5 active phase, leading to a lower CO conversion compared to FeZ-200. FeZ-180 with an appropriate assembly structure facilitates the contact between syngas and active sites, thus promoting the formation of the CFe_2.5 phase that enables a C₅–C₁₁ hydrocarbon selectivity of 62.9 wt% and a CO conversion of 93.6%. The preparation of hierarchical porous catalysts with controllable structures provides a novel strategy for the synthesis of functional catalysts.