Research progress on reaction networks and catalytic reaction mechanisms of phthalic anhydride synthesis

Phthalic anhydride is an important raw material for synthesizing high-value fine chemicals, such as plasticizers and coatings. In the recent decades, the production of phthalic anhydride from o-xylene is the main industrial process with minor from naphthalene. Vanadium-based catalysts are primarily employed in industry and have been widely studied due to their high selectivity for phthalic anhydride. In order to increase the yield of phthalic anhydride and reduce the bed temperature, strategies of multi-stage catalyst beds and high load have been gradually developed. This article focuses on the o-xylene synthesis process with a brief introduction of the development history of catalysts. Especially, the synthetic routes and catalytic mechanisms are discussed in detail. The application of industrial catalysts often faces deactivation problems, such as carbon compound deposition, loss of active components and TiO2 anatase-rutile transformation. Thus, the deactivation mechanism of catalysts is also discussed in detail. Finally, prospects for the development of synthetic technologies of phthalic anhydride are proposed. Towards the industrial problems of high energy consumption, COx generation, and short catalyst life, efforts should be made to develop new efficient catalysts and green reaction processes for the phthalic anhydride synthesis, so as to promote the sustainable development of this technology in the future. © 2024 Chemical Industry Press Co., Ltd.. All rights reserved.