GB841958A - Improvements in or relating to the catalytic refining of crude benzenes - Google Patents

Abstract

A process for the catalytic refining of crude benzenes by selective hydrogenation in the presence of hydrogen or a gas containing about 50% free hydrogen under elevated pressure and elevated temperature with catalysts, comprises supplying heat to the crude benzenes by means of hot hydrocarbon oil which together with the pre-treated crude benzenes is injected into an evaporating vessel from the bottom of which, said oil, correspondingly cooled, flows to a circulating pump which returns it through a heating up device into the evaporating vessel, while from the hot-oil cycle there is taken off in each case at least one quantity of oil corresponding to the quantity of polymerisate taken up therein and a quantity of fresh oil added such that the amount of oil in circulation remains constant, adding broken coke or another neutral solid substance preferably to the liquid circulation mixture and bringing the vapours issuing from a rectification column to the required reactor entry temperature only after the admixture of hydrogen or hydrogen-containing gas superheated to preferably at least 300 DEG C. The coke is preferably added to each circulation system individually, preferably by a sluice intermittently or continuously in suspension in the crude mixture, whereby an optimum solid substance concentration for the systems is maintained in each system.