水蒸气和空气活化对VPO催化剂物性及催化性能的影响

在对钒磷氧（VPO）催化剂的前躯体进行活化的过程中，分别采用空气和水蒸气/空气混合气作为活化氛围。通过X射线衍射（XRD）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）等表征手段，考察了不同气氛活化催化剂的晶相结构和表面性质。结果表明：采用水蒸气/空气活化的VPO催化剂主要晶相是(VO)2P2O7，而采用空气活化的催化剂主要晶相是VOPO4；水蒸气的加入降低了催化剂中钒的平均价态（AV值），提高了表面P/V原子比。当采用水蒸气/空气体积比1:3的混合气活化时，所得催化剂FVO-1的P/V原子比为1.17，AV值为4.198。 FVO-1催化剂对正丁烷选择性氧化制顺丁烯二酸酐反应的催化性能评价结果表明，正丁烷转化率达到87.10%，顺丁烯二酸酐选择性达到72.89%。

INFLUENCE OF STEAM AND AIR ACTIVATION ON THE PHYSICAL PTOPERTY AND CATALYTIC PERFORMANCE OF VPO CATALYSTS

Vanadium phosphate oxide (VPO) catalyst precursor was activated under the atmosphere of air and steam/air (S/A) mixed gas respectively. The activated catalyst samples were characterized by XRD, XPS and SEM to study their crystal structure and surface property. Results showed that after activation under S/A mixed gas and air, the main crystal phase of the catalyst was (VO)2P2O7 and VOPO4, respectively. The presence of water vapor during activation reduced the average valence state of vanadium (AV)，but increased the P/V atomic ratio of catalyst surface. The catalytic performance of these prepared catalysts was evaluated by selective oxidation of n-butane to maleic anhydride reaction. It was shown that catalyst FVO-1 activated by mixed gas with S/A volume ratio of 1/3, having an AV of 4.198 and P/V atomic ratio of 1.17 exhibited good catalytic performance: its conversion of butane was 87.10% and the selectivity of maleic anhydride reached 72.89%.