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.