新型WO3/TiO2纳米管催化剂的合成及其在环戊烯选择氧化反应中的 性能研究

采用水热合成法以P25为原料制备了介孔TiO2纳米管, 并根据TEM和XPS表征结果对其形成机理进行了初步分析. 然后, 以制备出的介孔TiO2纳米管为载体, 钨酸铵为钨源, 采用传统浸渍方法制备了介孔WO3/TiO2纳米管催化剂. 利用N2吸附, TEM, XRD, XPS及Raman等手段对固载后的多相催化剂进行了表征, 并研究了催化剂在环戊烯选择氧化制备戊二醛反应中的催化性能. 结果表明, 在介孔20% WO3/TiO2纳米管催化下环戊烯的转化率达97.9%, 戊二醛的选择性高达69.3%. 钨物种以高度分散状态存在于催化剂中, 并与载体间存在着较强的相互作用, 使得钨的溶脱量很小, 脱落的钨对反应几乎没有影响. 另外, 催化剂具有较高的稳定性, 可以重复套用7次. 失活后的催化剂可通过简单焙烧的方式再生.

Preparation of Novel WO3/TiO2 Nanotube Catalyst and Its Catalytic Performance for the Selective Oxidation of Cyclopentene

Titania nanotubes were synthesized via a simple alkali hydrothermal treatment of P25 (Degussa) nanoparticles and the formation mechanism of TiO2 nanotubes was primarily analyzed based on the characterizations by TEM and XPS. Then, the novel WO3/TiO2 nanotube catalyst was prepared by an incipient wetness method using the TiO2 nanotube as the support and ammonium tungstate as the precursor, and was characterized by means of N2 adsorption, TEM, XRD, XPS and Raman spectroscopy. The catalytic performance of the as-prepared composite was investigated for the preparation of glutaraldehyde (GA) from the selective oxidation of cyclopentene (CPE). The 20 wt% catalyst showed 97.9% of CPE conversion and 69.3% of GA selectivity. It was found that the active tungsten species were highly dispersed and there was strong interaction between tungsten species and the titania nanotube support at tungsten oxide content ＜20 wt%. The leaching of the active sites was very small and had little effect on the catalytic performance. In addition, the WO3/TiO2 nanotube catalyst was very stable and could be reused for at least seven times. The deactivated catalyst could be regenerated by simple calcination.