活化过程对正丁烷氧化制顺酐钒磷氧系催化剂性能影响的研究

Influence of Activation Procedure on Propertiesof Vanadium-Phosphorus-Oxygen Catalysts for Oxidation of Butane to Maleic Anhydride

本文在丁烷/空气气氛下,系统地考察了活化过程对正丁烷氧化制顺酐钒磷氧系催化剂性能的影响.活化前后的催化剂用XRD、IR、SEM、EPMA、TEM和比表面进行了较全面地表征,并与催化剂的活性进行了关联.结果表明:活化过程对催化剂相转变、比表面积、表面磷钒比(P/V)等有明显的影响.活化前后催化剂的形貌基本不变.实验证明(VO)_2P_2O_7是正丁烷选择性生成顺酐的活性相.催化剂活性防活化时间的增加而增长,并趋于稳定,但活性诱导期随之缩短.通过研究找到了工业催化剂的适宜活化条件,在该条件下活化的催化剂具有活性高、选择性好、活性诱导期短的特点.

In this paper, the effect of activation procedure in butane-air mixture on the performance of Vanadium-Phosphorus-Oxygen catalysts for oxidation of 'butane to maleic anhydride are systematically studied. The catalysts were characterized before and after activation by XRD, IR, TEM, SEM, EPMA and specific surface area determination. Experimental results indicated that activation procedure had an obvious influence on the phase transformation (precursor→ amorphous phase→(VO)2P2O7→β-VOPO4), specific surface area and surface phosphorus/vanadium ration of the catalyst. The morphology of catalysts remained unaltered during activation, but the platelets graduall ybacame smaller. It was shown that vanadyl pyfophosphate ((VO)2P2O7) is the active phase of the catalyst and the catalytic properties are related not only to surface area, but also to the phase composition. Furthermore, a catalyst containing primarily the active phase (VO)2p2O7 was obtained under appropriate activation condition. This catalyst exhibited high activity and good selectivity to maleic anhydride and approached to a steady activity in a short time.