GB814295A - Novel chromium oxide catalyst and method of preparing and utilizing the same - Google Patents

Abstract

Catalysts which may be used for polymerizing olefines or dehydrogenating paraffins, are made by mixing chromium oxide with an oxide of Al, Si, Ti, Zr or Fe and agitating the powdered mixture while heating at a temperature of 200 DEG to 374 DEG F. for at least 5 minutes, and preferably from 30 minutes to 50 hours. Agitation may be effected mechanically or by fluidizing the mixture preferably with an oxidizing gas. The product is then submitted to a further heat treatment at 650 DEG to 1000 DEG F., ground to 20/50 mesh, an organic binder added, formed into pellets and ignited. To the mixed oxides, promotors may be added, e.g. the oxides of Be, Mg, Sr, Cu, or KOH, and incorporated in the form of oxides, or as salt solutions forming oxides on heating. Alumina in the form of ground bauxite, alumina gel, or alumina hydrate is the preferred oxide to be added to the chromium oxide which may be at least partly in the form of the trioxide. The alumina may be pre-treated with H.F. Specifications 790,195, 790,196, 804,175, [Group IV (a)], 804,641, 804,642 and U.S.A. Specification 2,606,159 are referred to.ALSO:Olefines are polymerized by a catalyst made by mixing chromium oxide, preferably the trioxide, with an oxide of Al, Si, Ti, Zr, or Fe and agitating the finely powdered mixture while heating at a temperature of 200 DEG to 374 DEG F. for at least 5 minutes, and preferably 30 mins. up to 50 hours. Agitation may be effected mechanically or by fluidizing the mixture preferably with an oxidizing gas. The product is then re-heated to 650 DEG to 1000 DEG F., ground to 20/50 mesh, an organic binder added, formed into pellets and calcined. To the mixed oxides, promotors may be added, e.g. the oxides of Be, Mg. Sr, Cu or KOH. The alumina used may be pre-treated with HF. The final product contains about 15 to 45 per cent of chromium oxide, some part of which is in the form of the trioxide. 1-Olefines are treated containing up to 8 C atoms and no branching nearer than 4-position, e.g. ethylene, propylene, 1-hexene, 1-butene, and 1-pentene. Inert hydrogenation solvents may be used, and polymerization effected at 1500 DEG to 450 DEG and at 100 to 700 p.s.i. Specifications 790,195, 790,196, 804,175, 804,641, 804,642 and U.S.A. Specification 2,606,159 are referred to.