Patent GB-832296-A (GB)
Title: Process and catalyst for the dehydrogenation of hydrocarbons
IPC: B01J23/78
Filed: 1957-12-23
Abstract: A process for the dehydrogenation of an hydrocarbon comprises contacting each mol. thereof with 2 to 30 mols. of steam at not less than 580 DEG  C. and with a catalyst containing (i) one or more iron oxides having an average degree of oxidation between Fe3O4 and Fe2O3, the total iron oxide content being at least 35% calculated as Fe2O3; (ii) at least one potassium compound other than the chloride which is either the carbonate or convertible thereto under the reaction conditions in an amount equivalent to at least 6% K2O; and (iii) 0.1 to 2.5% of silica, the percentages being by weight of the Fe2O3+K2O+silica present, and (i) + (ii) constituting a major weight proportion of the whole catalyst. Potassium compounds specified are the hydroxide, nitrate, bicarbonate, sulphate and acetate.  The silica may be added as soluble metal silicates, silica sols and gels, or silicic acid, the K2O content of potassium silicate counting towards (ii). Other ingredients mentioned are 0.5 to 4% of oxide of heavy metals, e.g. Cr, Mn, Bi, W, Mo and Ce.  The catalyst ingredients may be compounded by mixing (e.g. ball-milling), co-precipitation, or impregnation of the iron oxide with the other components.  The iron oxide may be calcined, before or after compounding with the other components at 550 DEG  to 1050 DEG  C. for at least one hour.  The process is applicable to the dehydrogenation of n-butenes to butadiene and ethyl benzene to styrene.  At dehydrogenation temperatures of 580 DEG  to 700 DEG  C. the catalysts are autoregenerative, side reactions producing the small amount of carbon dioxide required.  In an example, n-butene-2 is dehydrogenated (35% conversion) with catalysts consisting of 62% Fe2O3, 2.2% Cr2O3, potassium carbonate equivalent to 24.1% K2O and 0.5, 1.0, 1.5 and 2.0 silica (balance CO2) at 620-660 DEG  C., 500 GHSV, and a steam : butene molar ratio of 12.ALSO:A process for the dehydrogenation of a hydrocarbon comprises contacting each mole. thereof with 2 to 30 moles. of steam at not less than 580 DEG  C. and with a catalyst containing: (i) one or more iron oxides having an average degree of oxidation between Fe3O4 and Fe2O3, the total iron oxide content being at least 35% calculated at Fe2O3; (ii) at least one potassium compound other than the chloride which is either the carbonate or convertible thereto under the reaction conditions in an amount equivalent to at least 6% K2O; and (iii) 0.1 to 2.5% of silica, the percentages being by weight of the Fe2O3+K2O+ silica present and (i)+(ii) constituting a major weight proportion of the whole catalyst. Potassium compounds specified are the hydroxide, nitrate, bicarbonate, sulphate and acetate.  Other ingredients mentioned are 0.5 to 4% of oxide of heavy metals, e.g. Cr, Mn, Bi, W, Mo and Ce. The iron oxide may be calcined, before or after compounding with the other components at 550 DEG  to 1050 DEG  C. for at least one hour. The process is applicable to the dehydrogenation of n-butenes to butadiene and ethyl benzene to styrene.  At dehydrogenation temperatures of 580 DEG  to 700 DEG  C. the catalysts are auto-regenerative, side reactions producing the small amount of carbon dioxide required.  In an example, n-butene-2 is dehydrogenated (35% conversion) with catalysts consisting of 62% Fe2O3, 2.2% Cr2O3, potassium carbonate equivalent to 24.1% K2O and 0.5, 1.0, 1.5 and 2.0 silica (balance CO2) at 620-660 DEG  C., 500 GHSV, and a steam : butene molar ratio of 12.