Abstract: Phthalic anhydride is continuously separated from the reaction gas mixture formed by the catalytic oxidation of o-xylene and/or naphthalene, by treating said rection gas mixture in at least two absorption stages with organic absorbents. The absorbent employed in the first absorption stage is a mixture of phthalic anhydride and benzoic acid. The absorbent employed in the subsequent absorption stage(s) contains maleic anhydride and may also contain phthalic anhydride.

Abstract: Phthalic anhydride is continuously separated from the reaction gas mixture formed by the catalytic oxidation of o-xylene and/or naphthalene, by treating said reaction gas mixture with a maleic anhydride absorbent.

Abstract: An improved process is provided for the recovery and storage of maleic anhydride from maleic anhydride-containing gases. Such gases are scrubbed with a water or maleic acid scrubbing solution in a scrubbing zone to form a maleic acid-containing solution. This maleic acid-containing solution is then concentrated and dehydrated in an evaporation zone and a dehydration zone, respectively, to form maleic anhydride. The maleic anhydride so formed is then purified by distillation in a distillation zone. The evaporation, dehydration, and distillation steps are all carried out under a vacuum maintained by withdrawing gases containing organic and water vapor from said evaporation, dehydration and distillation zones using jet pumps propelled by pressurized air. The vapor-containing gases so removed are admixed with the pressurized air pump propellant streams, and this mixture is then introduced into the scrubbing zone for the maleic anhydride-containing gases.

Abstract: Apparatus for the production and catalytic oxidation of gaseous hydrocarbon/air mixtures to form dicarboxylic acid anhydride. Hydrocarbon/air mixtures are formed in an evaporator and introduced into a shell-and-tube catalytic reactor fitted with a concave reactor hood to more effectively and safely distribute the gaseous mixture to and through the catalyst-filled tubes of the reactor.

Abstract: There is disclosed a process and apparatus for the thermal treatment of crude phthalic anhydride. The process is conducted in a system with an inner chamber and outer chamber positioned therearound and the chambers have a common wall. The outer chamber may be divided into a plurality of sub-chambers and the flow of the phthalic anhydride undergoing treatment may be substantially reversed in successive ones of the sub-chambers. The system provides for more efficient use of heat and equipment.