Hierarchical zeolite Y supported cobalt bifunctional catalyst for facilely tuning the product distribution of Fischer–Tropsch synthesis

• Hierarchical zeolite Y is prepared by the sequential leaching process.
• The mesopore volume increases after the sequential treatment.
• Low methane selectivity and excellent high isoparaffin selectivity are achieved.
• Better catalytic performance is attributed to the combine acidity and mesoporisity.

A two-step method consisting of acid leaching and base leaching was developed and applied to create hierarchical pores on a general microporous Y zeolite. Characterization with BET and TEM on the texture, morphology and structure of the prepared hierarchical Y zeolite confirmed the co-existence of mesopores with zeolitic walls. The analysis results showed that the mesopore surface area and pore volume of the hierarchical zeolite Y (Y-ABx, A: acid leaching, B: base leaching, “x” represents for base leaching time) increased with increasing the base leaching time. The hierarchical zeolite Y supported Co as catalysts were employed to catalyze the hydrogenation of carbon monoxide to form hydrocarbons through Fischer–Tropsch synthesis (FTS) reaction. The CO conversion and C5–11 selectivity on Co/Y-ABx catalysts increased significantly compared with those on the pristine Y supported Co catalyst. The isoparaffin selectivity of Co/Y-AB4 catalyst reached up to 52.3% and middle hydrocarbons became the main FTS products due to the optimized hydrocracking and isomerization function afforded by the hierarchical zeolite Y with the strong Brønsted acid/Lewis acid (B/L) ratio and textural property.

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