TWO STAGE PROCESS FOR THE PRODUCTION OF UNSATURATED CARBOXYLIC ACIDS BY OXIDATION OF LOWER UNSATURATED HYCROCARBONS

摘要

A process for the production of alpha-beta unsaturated carboxylic acid with high yield at low temperature and atmospheric pressure, includes two stages for catalytic vapor-phase oxidation of olefins with molecular oxygen. In a first stage, olefins are oxidized using catalyst A having a composition according to the formula: MoaPdbBicFedx1ex2fx3gOz, wherein X1 = one or more of Co, Ni, V, Pt, Rh; X2 = one or more of Al, Ga, Ge, Mn, Nb, Zn, Ag, P, Si, W; X3 = at least one or more of K, Mg, Rb, Ca, Sr, Ba, Na; and O = oxygen; to produce a first stage product containing alpha-beta unsaturated aldehydes. In a second stage, alpha-beta unsaturated aldehydes in the first stage product are oxidized using catalyst B having a composition according to the formula: MoaVbAlcXdYeOz wherein X = W or Mn or both; Y = at least one or more of Pd, Sb, Ca, P, Ga, Ge, Si, Mg, Nb, K; and O is oxygen which satisfies the valences of the other elements; to produce mainly alpha-beta unsaturated carboxylic acid. A portion of the oxygen is introduced into the reaction stream between the first and second stages or in multistages. More particularly, the invention relates to a two stage process for catalytic oxidation of propylene or iso-butylene to yield acrylic acid or methacrylic acid.