Hydropurification of Catalytically Cracked Gasoline

Abstract

New polyfunctional catalysts for hydrodesulphurization, hydroisomerization and hydrogenation of catalytically cracked gasoline have been developed. The activity of synthesized catalysts was studied for the above processes in flow conditions on a fixed bed at various temperatures and space velocities of the feed. Activity of studied catalysts depends on the nature of modified additives. Catalyst KT-17 modified by the zeolites HZSM-5, HY and other additives have high hydro-desulfurisation, hydroisomerization and hydrogenation activities compared to catalyst KT-18. The residual sulphur content is less than 0.01% in processed gasoline which corresponds to European standards. Decreasing of concentration of olefin with high octane numbers has small influence on octane number of catalytically cracked gasoline hydro-treated on KT catalysts. It is related with high degree of isomerisation of n-alkanes to isoalkanes. Temperature interval of 320-380°C is found to be suitable for high hydro-desulfurisation activity.with simultanesous decrease of olefin content and increasing isoalkanes concentration. Increasing of space velocity of raw material feed from 2.0 to 6.0 hour^-1 results in decreasing of desulfurisation degree from 97.3 to 91.1% and output of isoalkanes from 43.1 to 37.0%, increasing of olefins content in the reaction products from 11.9 to 33.0%. Catalysts KT-17 and KT-18 have poly-functional properties; reactions of hydro-desulfurisation, hydro-isomerisation and hydrogenation take place simultaneously and allow producing low sulfur, high octane and stable gasoline.