GB1153650A - Improvements in or relating to the Treatment of Hydrocarbon Oils - Google Patents

Abstract

1,153,650. Hydrodesulphurization and hydrodealkylation. POWER-GAS CORP. Ltd. 9 April, 1968 [11 April, 1967], No. 16501/67. Heading C5E. A hydrocarbon oil feedstock, e.g. the byproduct of the thermal cracking of naphtha into ethylene and propylene, containing organic sulphur compounds of the thiophene type and/ or olefines and diolefines is reacted with hydrogen or a hydrogen-rich gas in the presence of a catalyst, e.g. a molybdate of cobalt or nickel, at a temperature not exceeding 420‹ C. and at an elevated pressure to convert olefines and diolefines and organic sulphur compounds to paraffin hydrocarbons and hydrogen sulphide respectively, and the product is reacted, together with further hydrogen if necessary, at a temperature exceeding 520‹ C. and at an elevated pressure to hydrodealkylate aromatic compounds. If the feedstock contains a substantial proportion of diolefines it can be first reacted in the liquid phase at up to 200‹ C. with hydrogen using a catalyst containing nickel to convert the diolefines to olefines. The dealkylation is carried out non-catalytically at 650-790‹ C. or using a catalyst containing a molybdate of nickel or cobalt at 540-590‹ C. The formation of carbon during the dealkylation reaction may be inhibited by the addition of steam. The hydrodealkylated product is cooled and separated into a gas containing methane, ethane, hydrogen and hydrogen sulphide and a liquid containing the aromatic product and water. The aromatic product, e.g. 94À4% benzene, 4À3% toluene, and 1À3% xylene with 3 ppm of sulphur compounds, may be fractionally distilled to yield benzene and a toluene-xylene mixture which can be recycled to the hydrodealkylation reaction.