Catalyst for preparation of PMDA (pyromellitic dianhydride) by gas-phase oxidation of 1,2,4,5-tetramethylbenzene as well as preparation and application of catalyst

The invention relates to a catalyst for preparation of PMDA (pyromellitic dianhydride) by gas-phase oxidation of 1,2,4,5-tetramethylbenzene as well as preparation and an application of the catalyst, and belongs to the field of chemical synthesis. The catalyst for preparation of PMDA by gas-phase oxidation of 1,2,4,5-tetramethylbenzene is characterized by comprising an inert support and an active component supported on the inert support, wherein the active component is prepared from the following ingredients in percentage by weight: 50%-90% of TiO2, 1%-30% of alpha-Ti(HPO4)2.H2O, 5%-30% of V2O5, 0.1%-3% of alkali metal oxide and 0.1%-3% of Nb2O5, and the sum of the content of the ingredients is 100%. With adoption of the catalyst and a preparation method, selectivity and stability of the catalyst for preparation of PMDA by gas-phase oxidation of 1,2,4,5-tetramethylbenzene can be improved. When the catalyst is applied to production of PMDA, yield of PMDA can be increased effectively, andrunning period of a devi