Effect of the Composition of Synthesis Gas on a Combined Process of the Synthesis and Hydrofining of Hydrocarbons from CO and H2

Abstract

The results of studying the effect of the composition of synthesis gas (CO + H₂) on the combined process of hydrocarbon synthesis and hydrofining on the Co-SiO₂/ZSM-5/Al₂O₃ composite catalyst at a pressure of 2.0 MPa and a temperature of 240°C are presented. The raw material was concentrated synthesis gas and that diluted with nitrogen with H₂/CO ratios from 1 to 3 in the source gas. It was found that, as the H₂/CO ratio in the processed gas was increased from 1 to 3, the degree of CO conversion increased from 28.0 to 87.0%; selectivity for C₅₊ hydrocarbons decreased from 74.0 to 48.0%, and the fraction of unsaturated hydrocarbons decreased by a factor of 12. The dilution of synthesis gas with nitrogen also contributed to an increase in the degree of CO conversion from 75.8 to 84.0% and a small (~3%) increase in selectivity for C₅₊ hydrocarbons under the condition of the same ratio H₂/CO = 2 in diluted and concentrated synthesis gas. The amount of branched alkenes in a gasoline fraction increased from 14.0 to 32.5%, whereas it remained almost unchanged in a diesel fraction. The maximum catalyst productivity (108 kg m^–3 h^–1) was achieved with the use of synthesis gas with the ratio H₂/CO = 2.