| abstract |
Isobutyric acid is oxidatively dehydrogenated to methacrylic acid over a sulphate-free metal oxide catalyst contg. Mo oxide together with V, P and also an alkali metal, alkaline earth metal, Zm, Ag, Al, Ti, Pb, Mn, Fe, Co, Ni or Sn. The reaction pref. takes place in the gas-phase, using a gas mixt. of isobutyric acid, opt. water, O2 and N2. High yields are obtd. Selectively Selectivity for methacrylic acid can reach 60-74% at isobutyric acid conversions of 80-100. The catalyst is expressed esp. fby formula M(a)(Mo)b(V)c(P)d(O)e (I), (where M is K, Rb, Cs, Be, Mg, Ba, Zn, Ca, Ag, Al, Ti, Pb, Mn, Fe, Co, Ni or Sn; a is 0.4-2.5; b is 12; c is 1-2; d is 0.5-5 and e is determined by the valencies and proportions of the other elements). In pref. (I) M can be Mg, Ca or Al. Pref. (I) comprises compsns. having formula A1.5-2.Mo12.V1.5.P2.045-46 (where A is K, Rb or Cs). |