Bifunctional Hybrid FTS Catalyst Mixed with SAPO-34 Zeolite for Application in the GTL-FPSO Process

Abstract

The gas-to-liquid (GTL) process is a catalytic technology for achieving carbon neutrality during fuel production. Fischer？Tropsch synthesis (FTS), a core step in this process, converts synthesis gas (CO + H2) to high-value hydrocarbon products. This study synthesized a chabazite-shaped zeolite and a Co/γ-alumina catalyst by using conventional hydrothermal and wet impregnation methods, respectively. Hybrid FTS catalysts were then prepared by mixing the Co/γ-alumina catalyst with supports, including the synthesized and commercial zeolites alone and mixed at various ratios. The effects of these zeolites on the FTS conversion and selectivity were investigated. Additionally, the physicochemical properties of the supports and prepared catalysts were analyzed. The bifunctional hybrid catalyst performance was evaluated in a fixed-bed reactor, and the FTS products were analyzed using online and offline gas chromatography. The hybrid catalysts produced lighter hydrocarbons than the Co/γ-alumina catalyst alone. Meanwhile, heavy hydrocarbons produced over the Co/γ-alumina catalyst were hydrocracked at the acid sites of the silicoaluminophosphate zeolite (SAPO-34) to yield lighter, fuel-range hydrocarbons. Cobalt-based hybrid FTS catalysts were also investigated to determine the optimum support ratio for high carbon conversion and C5+ selectivity. The hybrid catalyst supported on SAPO-34:ZSM-5 (2:8) exhibited the highest CO conversion and favorable C5+ selectivity.