Abstract: A process for the recovery of five-membered ring dicarboxylic acid anhydrides from aqueous solutions of the corresponding dicarboxylic acids which entails (a) washing the aqueous solution of the dicarboxylic acid with a water-insoluble tertiary amine, and separating the resulting amine-acid salt from the water layer; and (b) adding an aromatic hydrocarbon entrainer for the water, removing the entrainer/water azeotrope by distillation and separating the five-membered ring dicarboxylic acid anhydride after phase separation; or adding an aliphatic hydrocarbon entrainer for the water, removing a ternary azeotropic mixture consisting of a hydrolytically stable anhydride, water and entrainer by distillation and separating the five-membered ring dicarboxylic acid anhydride after phase separation.

Abstract: Maleic anhydride is separated off from gaseous reaction mixtures by a continuous process in which the gaseous reaction mixture containing the maleic anhydride is brought into contact with butanol, the gaseous substances obtained in this procedure are brought into contact with butyl maleate by a countercurrent method, and the liquid product is removed from the bottom.

Abstract: A process for conducting a combination of fixed and fluid-bed catalytic reactions is achieved by employing fixed-bed catalysts on supports within the fluid bed. The fluid-bed catalysts may move in both directions through the fixed bed, thereby giving advantages of both types of beds in one reactor.

Abstract: In the dehydration of maleic acid to form maleic anhydride, comprising a first stage of concentrating an aqueous solution of maleic acid to 85-95% by maleic acid, and a second stage of dehydrating the concentrated maleic acid into maleic anhydride, in at least one of the stages, a falling film tubular evaporator is employed. Prior to the dehydration stage, about 15-35 parts by weight of maleic anhydride is added per 10 parts of concentrated acid.

Abstract: A stabilized heteropoly molybdate catalyst precursor in calcined form and containing anionic molybdenum in defect state is surface impregnated with certain metal cations. The stabilized precursor is one obtained by incorporating into the reaction product of a molybdate and a soluble phosphate, silicate or arsenate, an aqueous chloride ion and a compound of phosphotungstate, silicotungstate, vanadium arsenate, silico-arsenate, phosphovanadate, or silicovanadate, followed by drying and calcining. During the chloride ion stabilization step other metals may be optionally incorporated in forming the stabilized precursor.The obtained precursor is catalytically active in the conversion of the unsaturated aldehydes to the corresponding unsaturated carboxylic acids with or without incorporation of the metal cation during the chloride ion stabilization step.

Abstract: Process and system for cooling a reaction effluent containing volatized catalyst wherein the effluent is contacted with circulating cooled solid catalyst in dilute phase transport contact, with the volatized catalyst being condensed onto the solid catalyst.

Abstract: A method of preparation and/or purification of acid anhydrides is disclosed. Dicarboxylic or polycarboxylic acids contained in the anhydrides to be treated, are dehydrated in an organic solvent in the presence of activated carbon.

Abstract: A process for recovering maleic anhydride from gaseous compositions comprising maleic anhydride and water by condensing the composition at a temperature in the range of from about 20.degree. C. to about 50.degree. C. and a pressure of less than about 200 millimeters of mercury.

Abstract: A process for preparing 2-butenolide, a useful product for the manufacture of gamma-butyrolactone, is disclosed which comprises reacting furan with oxygen in the presence of a catalytically effective amount of a catalyst comprising a mixed metal oxide containing titanium, boron and molybdenum.

Abstract: A novel process for obtaining maleic anhydride having age molten and Hazen color below 125 after 20 hours at 140.degree. C., said process comprising polymerizing at a temperature of about 53.degree. to 90.degree. C. in the presence of metal chloride catalyst, color bodies present in crude maleic anhydride prior to fractionating the crude maleic anhydride and distilling off the purified maleic anhydride.