Catalyst for the oxidation of acrolein and methacrolein to acrylic acid and methacrylic acid, respectively

摘要

Catalysts which consist of a molded carrier, the surface of which is coated with an active catalyst composition of the general formula Mo12AaBbCcDdOx, where A is V and/or W, B is Cu and/or Fe and/or Mn and/or Ni and/or Cr, C is Nb and/or Ta and/or Bi and/or Sb and/or Sn and/or Th and/or Ce and/or U, D is Li and/or Na and/or K and/or Rb and/or Cs and/or Tl and a is from 0.1 to 18, b is from 0 to 8, c is from 0 to 10, d is from 0 to 2 and x is from 36 to 135, which are particularly active and selective for the oxidation of acrolein and methacrolein with oxygen-containing gases to give acrylic acid and methacrylic acid, respectively, are obtained by first manufacturing the catalyst composition, before applying it to the carrier, from thermally easily decomposed salts of the components by mixing aqueous solutions, slurries or moist solid masses of the salts of the components, drying the mixture and calcining the dried composition at from 140 DEG to 600 DEG C., then milling it to a particle size of less than 150 mu m and thereafter applying it, as a mixture with water, as a layer from 10 to 1,500 mu m thick, to the premolded carrier, which has a rough surface.