Process for the selective hydrogenation of diene-containing gasolines obtained by cracking

摘要

Diene-containing gasolines or fractions thereof obtained by the thermal cracking of a hydrocarbon oil with a final B.P. not above 250 DEG C., preferably in the presence of steam, are selectively hydrogenated at not more than 150 DEG C. while at least partly in the liquid state by contact with a catalyst containing chromium oxide and/or one or more compounds derived from chromium oxide and one or more oxides of elements of Group I-IV of the Periodic Table in the presence of added hydrogen. Generally the hydrogenation is effected at a pressure of 10-60, preferably 20-40 atm. abs., a space velocity of 0,5-5 Kg. gasoline/hr./litre catalyst and a gas/gasoline ratio of 50-300 1. (gas)/Kg. (gasoline). Suitable Group I-IV oxides are those of sodium, potassium, calcium, zinc, tin, magnesium, copper, barium, aluminium, scandium, titanium and silicon; the preferred catalyst however is one derived from chromium oxide and copper oxide in which the atomic ratio copper:chromium is 1:5-3:1, preferably 1:2-2:1. The hydrogen used may suitably comprise a mixture with light hydrocarbons, which mixture may be obtained from catalytic reforming processes. The catalyst is preferably treated with a hydrogen-containing gas before use. Specification 657,521 is referred to.