Abstract: Preparation of aliphatic alpha, beta-unsaturated carboxylic acids from the corresponding saturated acids by oxidative dehydrogenation, at a temperature between 250.degree. and 500.degree. C., in the presence of a catalyst of empirical formula: FeP.sub.x Me.sub.y Me'.sub.t O.sub.z wherein Me is at least one alkali or alkaline earth element, Me' is at least one element selected from the group consisting of Ni, Cu, Ce, Al, Zr, Hf and Pr, x is between 0.2 and 15, y is between 0.01 and 2, t is between 0.01 and 5 and z is such as to satisfy the valencies of the other elements.

Abstract: Alpha, beta-unsaturated monocarboxylic acids, in particular methacrylic acid, are esterified in the vapor phase in contact with a catalyst containing, in combination with oxygen, tungsten alone or in admixture with one or more of the elements lithium, sodium, potassium, rubidium and cesium.

Abstract: Alpha, beta-unsaturated acids are obtained by gas-phase catalytic oxidation of saturated acids containing from 3 to 8 carbon atoms. The catalyst used has the empirical compositionFeP.sub.x Me.sub.y O.sub.zin whichMe is one or more of the elements Li, Na, K, Rb, Cs, Mg, Ca, Sr and Ba;x is 0.2 to 3;y is 0.01 to 2; andz is a value corresponding to the average valences of the elements in the oxidation states in which they exist in the catalyst.THE PRIOR ARTThe catalytic dehydrogenation of lower aliphatic acids is known and has been described previously. According to one known process, for example, a metal oxide is used as a catalyst and reagent, and dehydrogenation is conducted in the absence of molecular oxygen.