GB1071253A - Selective hydrogenation of hydrocarbons - Google Patents

Abstract

A process for the selective non-destructive hydrogenation of a liquid hydrocarbon feed containing olefines and diolefines comprises passing said feed substantially in the liquid phase through a hydrogenation zone in contact with a porous solid hydrogenation catalyst having a hydrogenation activity index of at least 40 or having a benzene conversion index of at least 50 and having in either case a polymerization activity index less than 35, with a hydrogen charge of 500 to 5,000 standard cubic feet per barrel of feed at a hydrogen inlet pressure of 200 to 1,000 lbs. per square inch, with a liquid hourly space velocity of 0.2 to 15.0 volumes of feed per volume of catalyst, the foregoing conditions and the average reaction temperature being correlated to obtain a mixed phase hydrogenation effluent from said hydrogenation zone in which diolefines have been at least partially saturated; vaporizing a predetermined portion of the liquid phase of said hydrogenation effluent; passing a gaseous material derived from said vaporizing through a subsequent conversion zone in contact with a porous solid conversion catalyst having a desulphurization activity index of at least 80, at a substantially higher average temperature than in said hydrogenation zone, with a total hydrogen charge of 500 to 10,000 standard cubic feet per barrel of feed at a hydrogen partial pressure of 200 to 800 lbs. per square inch, with a liquid hourly space velocity of 0.2 to 6.0 volumes of feed per volume of catalyst to produce a substantially desulphurized conversion effluent having a substantially lower bromine number than said liquid feed. The hydrogenation zone preferably operates at a temperature below 200 DEG F. and the conversion zone at an inlet temperature of 350 DEG to 700 DEG F. The feed stock may be a pyrolysis gasoline boiling below 400 DEG F., preferably between 90 DEG and 240 DEG F., containing olefines and diolefines. The hydrogenation catalyst may be platinum, rhodium or palladium on alumina; nickel; or copper chromite. The nickel may be supported on kieselguhr, and palladium on activated carbon is also referred to. The catalyst for the conversion stage may be tungsten disulphide, nickel sulphide, nickel-tungsten sulphide or chromia on alumina promoted by molybdena. Oxides or sulphides of cobalt and molybdenum supported on gamma alumina are also referred to. There is preferably added to the gaseous phase formed from vaporization of the effluent from the hydrogenation zone a substantial amount of a liquid non-volatile flux which may be any liquid substance which is more volatile at any temperature attained by it in the process and is miscible with and unreactive with the liquid feed. This flux may be the least volatile portion of the liquid effluent from the hydrogenation stage.