High productivity process to produce maleic anhydride from n-butane

Abstract

In producing maleic anhydride by catalytic oxidation of n-butane in vapor phase using oxygen or enriched air as oxidation medium, the reaction mixture consists of butane, oxygen and a recycling exhaust gas recovered from the absorption stage by a solvent of the maleic anhydride produced in the reaction. In the instant process the carbon monoxide and the carbon dioxide concentration in the reactor mixture are held to on optimum level by performing the reaction on a suitable V.P.O. catalyst, and by feeding to the recycling gases, in addition to butane and oxygen, a carbon dioxide rich gas stream. The carbon dioxide rich gas stream can be produced either by selective absorption and desorption of carbon dioxide from a gaseous stream purged from the recycling exhaust gases or by selective separation on membranes of a carbon dioxide rich stream from the purge gas stream, or by selective catalytic oxidation of carbon monoxide to carbon dioxide of a gaseous stream purged from the recycling exhaust gases. As an alternative, a carbon dioxide rich gas from an external source can be used. The yield of the process is further improved by recovering a large percentage of the butane contained in the purge gas by a special absorption technique. Compared with the conventional technology, the process offers superior yield, higher productivity, reduced energy of compression, safer operation, reduced environmental impact due to a remarkable reduction in carbon dioxide release.