The remarkable effect of the preparation procedure on the catalytic activity of CoBEA zeolites in the Fischer–Tropsch synthesis

• The most active catalysts were Red-C-CoxSiBEA with high CO conversion of 90–95%.
• The selectivity towards liquid hydrocarbons (C7–C18) on these catalysts was 85%.
• Cobalt nanoparticles in Red-C-CoxSiBEA were much better dispersed than that in Red-C-CoxAlBEA.
• The carbon deposition on Red-C-CoxSiBEA was lower than that on Red-C-CoxAlBEA.

This work deals with the investigation of the influence of the preparation procedure and Co content on the activity of CoBEA zeolite in Fischer–Tropsch synthesis. For this purpose the Co-containing zeolites were prepared by a conventional wet impregnation (CoxAlBEA series) and a two-step postsynthesis method (CoxSiBEA series). Calcination at 500 °C, for 3 h in air and then reduction at 500 °C in flow of 95% H2–5% Ar stream of as prepared CoxAlBEA and CoxSiBEA zeolites led to obtain Red-C-CoxAlBEA and Red-C-CoxSiBEA catalysts with different properties in Fischer–Tropsch reaction. The most active catalysts were Red-C-Co10SiBEA and Red-C-Co20SiBEA with high CO conversion of 90–95% and selectivity towards liquid products of 85% containing C7–C18 n-alkanes, isoalkanes and small amount of olefins. In the case of Red-C-CoxAlBEA catalysts the CO conversion was of 68% and selectivity towards liquid products of 57%. The identified liquid products were mainly C7–C16 n-alkanes. Moreover, Red-C-CoxSiBEA catalysts demonstrated better stability and resistance to coke formation than Red-C-CoxAlBEA ones. It is probably related to higher dispersion of cobalt nanoparticles in Red-C-CoxSiBEA than in Red-C-CoxAlBEA catalysts and absence of strong Brønsted acidic sites in the former after removal of aluminum in the first step of two-step postsynthesis preparation procedure.

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