GB655210A - Oxidation of olefines - Google Patents

Abstract

Acrolein and methacrolein are manufactured by the catalytic oxidation of propylene and isobutene respectively with gases containing molecular oxygen at temperatures between 230 DEG and 400 DEG C., the reacting gases in the presence of elementary selenium passing over a contact material which comprises initially copper oxide on activated alumina or alternatively copper aluminate. Elemental selenium may be mixed with the contact mass or a decomposable selenium compound, e.g. a selenide of copper, silver, cobalt or lead may be added. Preferably vaporous selenium is added to the olefine-oxygen containing gas reaction mixture before passing it over the contact mass. The efficiency of the contact material is increased by heating. As oxygen containing gases may be employed commercially pure oxygen or oxygen diluted with inert gases or vapours such as nitrogen, carbon dioxide and steam, the last two being easily removed by scrubbing or condensation. In examples (1)-(4) contact materials are prepared by immersing granulated activated alumina in copper nitrate solution, drying and igniting, followed in examples (1), (3) and (4) by further heat treatment. Propylene or isobutene, mixed with oxygen and carbon dioxide, is passed over heated selenium and then over the heated contact material to form acrolein or methacrolein. In example (5) propylene with oxygen carbon dioxide and selenium vapour is passed over heated copper aluminate prepared by evaporating a solution containing copper nitrate and aluminium sulphate to dryness and heating. Specifications 625,330, 648,386 and 658,179 are referred to.ALSO:In a process for the manufacture of acrolein and methacrolein by the catalytic oxidation of propylene and isobutene respectively with gases containing molecular oxygen at temperatures between 230 DEG and 400 DEG C. the reacting gases, in the presence of elementary selenium are passed over a contact material which comprises initially copper oxide distributed upon activated alumina or copper aluminate. Elemental selenium may be admixed with the contact mass or it may be generated in situ from selenium compounds, admixed with the other components forming the contact material, which decompose under the reaction conditions to liberate elementary selenium, e.g. the selenides of copper, silver, cobalt or lead. Preferably the elementary selenium is added in the form of vapour to the olefine-oxygen mixture before the latter is passed over the contact material. The efficiency of the copper oxide-activated alumina contact material may be increased by a preliminary heating at elevated temperatures. The copper oxide is converted to some extent into copper aluminate. Contact masses are prepared in examples (1)-(4) by immersing granular, activated alumina in copper nitrate solution, igniting the product and applying further heat treatment in examples (1), (3) and (4). In example (5) copper aluminate, obtained by evaporating to dryness an equimolar solution of Cu(NO3)2 and Al2(SO4)3 and furthe heat treating the product, is extracted with dilute nitric acid, dried and compressed into pellets. Mixtures of propylene or isobutene with oxygen and carbon dioxide or air together with selenium vapour are passed over the contact masses at elevated temperatures to obtain acrolein and methacrolein (see Group IV (b)). Specifications 625,330, 648,386 and 658,179, [Group IV (b)], are referred to.