| Although the output of maleic anhydride is No.1 in the world, the benzene oxidation is the dominant technology in our country. Due to the restrictions on the price of material and the requirement of environment protection, it has been a trend that the benzene oxidation is replaced by N-butane oxidation. In order to take full advantage of the main process equipments in the benzene oxidation technology, it is imperative that the transformation of process route should be accomplished by changing catalyst and process parameters. As a result, it is essential to develop a type of industrial catalyst with better performance and longer lifetime.The industrial-grade material (main material) was chosen in the topic.The catalyst with better performance was chosen to advance its process conditions, based on the orthogonal experiment for defining the more suitable preparation conditions, including the catalyst precursors preparation conditions influencing on VPO catalyst performance, adding differently promoters, differently drying rate, activated ambience、activation temperature, activation time, and so on.In view of the result of XRD and IR, the phase of activating catalyst had transformed from VOHPO4·0.5H2O into (VO)2P2O7, which was the activated ambience of catalyst decides the final formation. It was indicated that the better activated ambience was developed in the reactive atmosphere. The lower drying rate was good to the improvement of catalyst performance with the activation temperature of 450 ℃ and the activation time of 2 h. Also the selectivity of the catalyst was improved to the level of 70%, with the promoter element Zr, which was benefit for the existence of (VO)2P2Oy.Through the evaluations of catalysts under various temperatures, space velocity and the concentration of oxygen and n-butane, the optimized process conditions were determined, including reaction temperature of 420℃, initial n-butane concentration of 1.5 %,space velocity of 1800h-1. The MA mass yield reached to 56.7%. |
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