A Study On The Preparation Of Fixed Bed Catalyst For Oxidation Of N-Butane To Maleic Anhydride

In this paper, the preparation of fixed bed catalyst for oxidation of n-butane to maleic anhydride has been studied, and the influence of different technological conditions on the catalyst behavior was investigated. In the experiments of catalyst preparation, n-butanol and benzaldehyde were used as solvent and reducing agent. With statistical experiment method, effects of reacting time, reacting temperature, suitable solvent / solute ratio (n-butanol + benzaldehyde cm3/V2O5 g) and the concentration of the acid added during the preparation of catalyst precursor, have been investigated. On the basis of these, the effect of acid concentration on catalyst behaviors was emphatically studied. And experiments of precursor preparation at elevated temperature and pressure have been carried out。For the catalysts prepared at higher concentrations of acid, the quantity of V4+ phase (VO)2P2O7 is quite large, and the n-butane conversions are all considerably high. With decreasing the acid concentration in precursor preparation, the relative amount of V5+ phase δ-VOPO4 and the n-butane conversion increase continuously, whereas the selectivity to MA increases at beginning and then decreases when it reaches a maximum value. The catalyst prepared at the acid concentration of 95.0 % gave the maximum yield of MA of 45.49% at an inlet n-butane concentration of 2.0%and a space velocity of 500h-1.As well as that with the promoter element Zr (NO3)4 was added. Chemical analysis of oxidation state of vanadium in the catalyst was carried out and X-ray diffraction measurements were taken for the catalysts. Variation of the catalyst activity and selectivity with phase composition of the catalyst has been explained theoretically.