GB820403A - Improvements relating to the catalytic reforming of petroleum hydrocarbons - Google Patents

Abstract

The octane number of a catalytic reformate or portion thereof is increased by contacting it with a dehydrogenation and dehydrocyclization catalyst at elevated temperature and not more than 50 p.s.i.g., in the absence of hydrogen either extraneously added or recycle. A platinum reformate is the preferred starting material, and a lower-boiling fraction is preferred, which fraction after treatment may be blended back with the high-boiling fraction; such a blend may be less volatile than the original reformate and the volatility may be increased by adding to the fraction to be treated material boiling below the initial boiling point of the reformate, or the treated fraction and higher boiling fraction blended in proportions to give adequate volatility, T.E.L. being added to maintain the octane number, or the end boiling point of the lower-boiling fraction may be adjusted to exclude toluene-forming components. The catalyst is preferably a chromia-alumina containing 5-25% chromium oxide, 0.1-5% alkali metal (as oxide) 0.1-5% rare earth metal (as oxide) preferably cerium and the balance alumina. Pressures below atmospheric may be used but atmospheric is preferred, temperatures of 450-580 DEG C. and space velocities of 0.1-1 vol./vol./hr. may be used. Fixed, fluidized or moving bed techniques are operable and the catalyst is readily regenerated conventionally. Hydrogen gas is removed as by-product. Examples are given of the treatment at atmospheric pressure of (1) a light platformate boiling 34-108 DEG C. at 530 DEG C. and 0.2 vol./vol./hr; (2) a light platformate boiling 42-110 DEG C. at 492 DEG C. and 0.2 vol./vol./hr., 521 DEG C. and 0.21 vol./vol./hr. and 549 DEG C. and 0.19 vol./vol./hr., the products being blended with a heavy platformate boiling 125-214 DEG C.; (3) a total platformate boiling 92-177 DEG C. at 525 DEG C. and 0.2 vol./vol./hr.; (4) a heavy platformate boiling 114-213 DEG C. as in (3). Examples are also given showing the effect of varying temperature, alkali metal promoter and pressure and comparing treating a light reformate and blending with the heavy reformate to treating the whole reformate. The catalyst in each case is promoted chromia-alumina as described.