Influence of the Structural Characteristics of VPO Catalysts on the Temperature Sensitivity of the Oxidation Reaction of n‑Butane to Maleic Anhydride

In the oxidation of n-butane to maleic anhydride (MA), increasing temperature leads to increased conversion accompanied by decreased selectivity to MA; this trade-off effect between selectivity and conversion of catalysts is important in maximizing the MA yield. The relationship between the structure and the catalytic performance is investigated in detail to understand the effects of the nature of the catalyst on the temperature sensitivity of its performance, which are neglected in the literature. The analysis of the studied industrial catalysts reveals differences in the temperature sensitivity, surface P/V ratio, and the nature and amount of V5+ species. Furthermore, a series of catalysts with different P/V ratios and different V5+ species is prepared to confirm the different influences of structural features on the temperature sensitivity of the catalytic performance. The results suggest that the surface P/V ratio is negatively correlated to the temperature sensitivity of n-butane conversion and MA selectivity, and isolated V5+ species contribute to the low-temperature sensitivity of MA selectivity while affecting the temperature sensitivity of n-butane conversion to a lesser extent. The structural characteristics of VPO catalysts suitable for partial oxidation of n-butane to MA in industrial processes are proposed, which provide theoretical guidance for the development of catalysts.