Patent GB-536497-A (GB)
Title: A process for the catalytic treatment of hydrocarbons
IPC: C10G35/06
Filed: 1939-11-20
Abstract: 536,497. Catalytic dehydrogenation of hydrocarbons. NAAMLOOZE VENNOOTSCHAP DE BATAAFSCHE PETROLEUM MAATSCHAPPIJ. Nov. 20, 1939, No. 30402. Convention date, Nov. 30, 1938. [Class 2 (iii)] [Also in Group III] The aromatic content of hydrocarbon mixtures containing cyclo-paraffinic and/or cycloolefinic hydrocarbons boiling within the gasoline range is increased by a catalytic dehydrogenation treatment which comprises contacting the hydrocarbon mixture with a catalyst composed of aluminium oxide and chromium oxide in the molecular ratios of (10-40):(90-60) at temperatures between 400‹C.-600‹C. preferably in the presence of hydrogen. The activity of the catalysts may be increased by the addition of alkaline compounds such as alkaline hydroxides, carbonates, nitrates, sulphates and phosphates. The amount of such added alkaline materials is not more than 30, and preferably 15-20 atoms of alkali metal per 100 mols. of oxide mixture. The process may be carried out at normal, raised, or reduced pressure. The oxides used as catalysts are prepared in such a manner as to ensure the formation of a large surface area, such as by precipitation, or by heating their oxalates, acetates. The aromatic hydrocarbons produced by the process of the invention are effective as motor fuels with high anti-knock properties. In an example, methyl cyclohexane was passed at 10 ccs. per hour at 465‹C. at atmospheric pressure over 18 ccs. of a mixture of 30 mol. per cent. of aluminium oxide and 70 mol. per cent. of chromium oxide with the addition of 18 atoms of potassium in the form of potassium hydroxide, the catalyst being compressed into pastilles. An average of 83 per cent. by weight of methyl cyclo-hexane was converted into aromatic hydrocarbons mainly consisting of toluene. The Specification as open to inspection under Sect. 91 includes also the inclusion of the alkali metal in the chromium-aluminium oxides by adding the alkali in the form of a solution of an alkali salt prior to drying. Salts mentioned include the sulphate, nitrate, carbonate, hydroxide, oxide, phosphate, bicarbonate, borate, and aluminium salts of organic acids. Additional details are also given relating to the preparation of the catalyst and it is stated that the catalysts may be improved by the presence of small amounts of promotors such as copper or thallium compounds. In additional examples (1) a fraction of a Venezuelan straight run gasoline containing 5-ring naphthenes is forced under a pressure of 15 atmospheres with about 4 per cent. hydrochloric acid through an autoclave containing aluminium chloride at 80 ‹C, The reaction product now largely converted to 6-ring naphthenes was passed over a catalyst compound of 30 mol. of Al 2 O 3 , and 70 mol. of Cr 2 O 3  and also containing 4.5 per cent. by weight of potassium in the form of KNO 3 . Hydrogen was also passed with the gasoline fraction. A considerable conversion to aromatics took place. (2) a Borneo gasoline was treated with Aluminium chloride as above and then passed over a similar catalyst, containing additional potassium added in the form of potassium hydroxide. This subjectmatter does not appear in the Specification as accepted.