GB998465A - Process for preparing ª‡ú¼ª‰-unsaturated aldehydes and ketones from olefines containing at least three carbon atoms - Google Patents

Abstract

a ,b -Unsaturated aldehydes or ketones are prepared by oxidizing an olefin having at least 3 carbon atoms in a gaseous phase in the presence of molecular oxygen, steam and a catalyst comprising a solid thermostable oxygen-containing compound of phosphorus and of at least one of molybdenum, tungsten and vanadium in at least two reaction stages, in such a manner that the gaseous mixture obtained after one reaction stage is introduced into the next reaction stage after the major portion of the carbonyl product has been removed and subsequently a further quantity of steam and oxygen is added so that at the end of the last reaction stage more than 70% of the olefine introduced into the first reaction stage has been converted into a ,b -unsaturated aldehydes or ketones. The catalyst may also contain as optional constituents oxygen-containing compounds of iron, cobalt, manganese, antimony, bismuth, tellurium, coppers, nickel, cerium, silver or palladium. Any unused olefin from the final stage may be recycled to an earlier stage. The catalyst may be of different composition in the different stages and may be supported on conventional materials, e.g. alumina, titanium dioxide, zirconium dioxide, pumice, silicon carbide and, in particular, those containing silicic acid, e.g. kieselguhr and/or silica gel. The olefins used as starting materials may be diluted, for example with methane, ethane, propane, butanes, ethylene, or nitrogen or carbon oxides. The preferred catalyst is one comprising oxides or mixed oxides of molybdenum, bismuth, iron and phosphorus. The process is preferably carried out at 300-500 DEG C. The process may, for example, be used for the conversion of propylene, isobutylene and butylene to acrolein, methacrolein and methylvinyl ketone respectively.ALSO:A catalyst for use in the oxidation of olefines comprises a solid thermostable oxygen-containing compound of phosphorus and of at least one metal selected from molybdenum, tungsten and vanadium. Optional constituents of the catalyst are oxygen-containing compounds of iron, cobalt, manganese, antimony, bismuth, tellurium, copper, nickel, cerium, silver, or palladium. The preferred catalyst is one comprising oxides or mixed oxides of molybdenum, bismuth, iron and phosphorus. The catalysts may be supported on conventional supports, e.g. alumina, titanium dioxide, zirconium dioxide, pumice, silicon carbide and, particularly, kieselguhr and/or silica gel. In general, the grain size of the catalyst is in the range 2-6 mm.