DESULFURIZATION PROCESS FOR REMOVAL OF REFRACTORY ORGANOSULFUR HETEROCYCLES FROM PETROLEUM STREAMS

摘要

Hydrocarbon feeds are upgraded by contact of the stream under hydrodesulfurization (HDS) conditions with a catalyst system comprising a sulfided, transition metal promoted tungsten/molybdenum HDS catalyst, e.g., Ni/Co-Mo/A12O3 and a solid acid catalyst which is effective for the isomerization/disproportionation/transalkylation of alkyl substituted, condensed ring heterocyclic sulfur compounds present in the feedstream, e.g. zeolite or a heteropolyacid compound. Isomerization, disproportionation and transalkylation reactions convert refractory sulfur compounds such as 4- or 4,6-alkyl dibenzothiophenes into corresponding isomers or disproportionated isomers which can be more readily desulfurized by conventional HDS catalysts to H2S and other products. A hydrocarbon feed is first passed to a hydrotreating reactor (1). The effluent from the hydrotreating reactor (1) goes through a high-pressure gas-liquid separator (2) and is passed to a fractionator (3). The fractionator bottoms are passed to reactor (4) and effluent from reactor (4) is recycled to hydrotreater (1).