中文摘要：

研究了酸性助剂对TiO2纳米管(TNT)负载的V2O5催化剂(V2O5/TNT)性能的影响, 发现经硫酸、磷酸或磷钨酸处理后, TNT的结构稳定, 但表面酸性和氧化-还原性发生了变化, 从而改变了甲醇选择氧化为甲缩醛的催化性能. 实验结果表明, V2O5/TNT催化剂经硫酸修饰和673 K焙烧, 其甲缩醛选择性显著提高, 且维持了较高的甲醇转化率. 催化剂表征表明, 高温焙烧促进了硫酸根与钒物种之间的强相互作用, 从而提高了催化剂的表面酸性而没有降低钒的氧化-还原性. 磷酸和磷钨酸修饰虽然也提高了V2O5/TNT催化剂的表面酸性, 但降低了其中钒氧化物的氧化-还原能力, 反而降低了催化剂的活性.

英文摘要：

The effect of acidic promoters on the titania-nanotubes(TNT) supported V2 O5 catalysts(VTNT) was investigated.The structure of TNT was quite stable after the treatment with sulfuric,phosphoric,and phosphotungstic acids,respectively.The acid-modified VTNT catalysts were tested for the se- lective oxidation of methanol to dimethoxymethane(DMM).It was found that only the VTNT modi- fied with sulfuric acid followed by calcination at 673 K exhibited the significantly enhanced selectiv- ity to DMM with high methanol conversions.The calcination created some sulfate groups strongly interacted with vanadium species,which enhanced the strengths of surface acidity without weak- ening the redox ability of vanadium sites.The addition of phosphoric and phosphotungstic acids might enhance the surface acidity of V2 O5 /TiO2,but weakened its redox ability,and therefore had the negative effect for the target reaction.