GB1255554A - Process for treatment of coke oven light oil - Google Patents

Abstract

1,255,554. Recovering aromatics. AIR PRODUCTS & CHEMICALS Inc. 2 April, 1969 [6 May, 1968], No. 17197/69. Heading C5E. Aromatic hydrocarbons are recovered from coke oven light oils containing at least 10% by volume of primary light oil (including naphthalene and other bicyclic compounds) by the following steps: (a) contacting the oil with hydrogen and a recycled heavier oil fraction (see step (d) below) in an upflow hydrogenation reactor operating under substantially liquid phase conditions and containing a hydrogenation catalyst, e.g. sulphided cobalt molybdate/ alumina; (b) subjecting the effluent from (a) to gas-liquid separation; (c) fractionating the liquid from (b) to obtain a vapour overhead fraction (comprising mainly monocyclics) and a heavier oil fraction (comprising bicyclics and higher); (d) recycling at least part of said heavier oil fraction to step (a), the volume ratio of heavier oil to fresh feed being in excess of 1 : 1; (e) hydrodealkylating the overhead fraction from (c) in the presence of a dealkylation catalyst, e.g. chromia/alumina; and (f) recovering aromatics from the dealkylation effluent. Step (a), which serves mainly to selectively hydrogenate polymerizable unsaturates, and uses excess hydrogen, may be operated either under severe conditions, e.g. 285-370‹ C., in which case there is also some hydrogenation of the bicyclic compounds present, or under mild conditions, e.g. 250-285‹ C., in which case the heavy oil fraction from step (c) may be further fractionated to produce a naphthalene heart cut before recycling of the remainder to step (a). Flow diagrams show both alternatives. The gas-phase separated in step (b) may be used to provide part of the hydrogen for step (e). Step (e) may also result in removal of sulphur compounds and non-aromatics by hydrocracking. In Example 1, benzene is the main product, toluene also being obtained. In Example 2, the products are naphthalene and a BTX fraction.