VERFAHREN ZUR OXYDATION VON PROPYLEN ZU ACROLEIN UND VON ACROLEIN ZU ACRYLSAEURE IN GEGENWART WASSERFREIER VERDUENNUNGSMITTEL

The processes for oxidation of propylene to acrolein and the oxidation of propylene to acrylic acid in two stages with acrolein as an intermediate are improved by use of anhydrous diluent gases to reduce or replace steam in the reaction streams. In particular, the use of anhydrous diluents which raise the composite flowing heat capacity of the diluent gas mixture to at least about 6.5 calories/gram-mole ( DEG C) will improve selectivity to desired products and will reduce the water load on the system. Reduction in second-stage catalyst efficiency is compensated for by introducing steam to the feed to the second stage, and/or by increasing the operating temperature of the second stage, and/or increasing the active surface area of the second/stage catalyst.