Method of Collecting Pyromellitic Dianhydride

The methods of collecting pyromellitic dianhydride which is low concentration from the high temperature reaction gas prepared by the gas phase catalytic oxidation of durene are introduced.The advantages and disadvantages of direct and indirect cooling technologies are presented from the aspects of reaction conditions,floor space of equipments,yield of crude products,purity of pyromellitic dianhydride,types and numbers of collecting device,labor intensity and working environment and etc.Through the comparison and analysis it concludes that the direct cooling collecting methods by organic solvent and water-air will be the study and development trends of technologies of collecting pyromellitic dianhydride.