Preparation of catalyst consisting of carrier and catalytically active oxide material applied to surface of carrier

A catalyst having a catalytically active oxide on the surface of a carrier is mfd. by moistening the carrier with a liq. binder consisting of a soln. of 10-80 wt.% of organic binder dissolved in 20-90 wt.% of H2O, contacting its surface with finely divided oxide particles, and removing the binding agent. The organic binder has a b.pt. or sublimation temp. of > 100 degrees C at atmos. pressure. Also claimed are: (i) a shell catalyst consisting of a hollow cylinder carrier 2-10 mm long with an external dia. 4-10 mm and a 1-4 mm wall thickness coated on its external surface with an oxide of general formula Mo12VaX bX cX dX eX fX6gOn in which, X is W, Nb, Ta, Cr and/or Ce, X is Cu, Ni, Co, Fe, Mn and/or Zn, X is Sb and/or Bi, X is 1 or more alkali metals, X is 1 or more alkaline earth metals, X is Si, Al, Ti and/or Zr and a = 1-6, b = 0.2-4, c = 0.5-18, d = 0-40, e = 0-2, f = 0-4, g = 0-40 and n is a number determined by the valency and the abundance of the different elements in the general formula. The thickness of oxide is 10-1000 mu m, the specific active surface is 20-30 m /g and a value of < 0.5 wt.% is obtd. in a rotating table attrition test; and (ii) a shell catalyst of similar dimensions and final physical properties of general formula Mo12BiaFebX cX dX eX fOn in which, X is Ni and/or Co, X is Tl, an alkali metal and/or an alkaline earth metal, X is P, As, B, Sb, Sn, Ce, Pb, Nb and/or W, X is Si, Al, Ti and/or Zr and a = 0.5-5, b = 0.01-3, c = 3-10, d = 0.02-2, e = 0-5, f = 0-10 and n is a number determined by the valency and the abundance of the different elements in the general formula.