Patent ID: 8022254

Claim:
Catalyst comprising a member selected from the group consisting of: (a) alkali tungstate, wherein the alkali tungstate contains a combination of two bonded alkali metals and selected from the group consisting of: a) potassium and caesium, b) sodium and caesium, c) rubidium and caesium, d) sodium and potassium, e) rubidium and potassium, and the alkali tungstate contains at least one halide selected from the group consisting of C1, Br and I, wherein the molar ratio of the sum of the alkali metals to tungsten of from 0.9:1 to <4:1 and in a molar ratio of the sum of halides to the sum of alkali metals of from 0.01 : 1 to 3:1; and (b) alkali tungstate, wherein the alkali tungstate contains at least two halides selected from the group consisting of F, C1, Br and I, with the proviso that the alkali metal is selected from at least one element of the group of the Periodic Table of Elements, wherein the tungstate contains at least one bonded alkali metal, tungsten and the at least two halides in a molar ratio of the sum of the alkali metals to tungsten of from 0.9:1 to <4:1 and in a molar ratio of the sum of halides to the sum of alkali metals of from 0.01 : 1 to 3:1.