摘要
利用ＴＰＲ（程序升温还原）方法研究了ＷＯ３／γ－Ａｌ２Ｏ３及ＷＯ３／ＴｉＯ２－Ａｌ２Ｏ３催化剂的还原过程。结果发现，随着ＷＯ３负载量的增加，ＷＯ３／γ－Ａｌ２Ｏ３样品的ＷＯ３还原温度逐渐降低。对于ＷＯ３／ＴｉＯ２－Ａｌ２Ｏ３作品，当ＷＯ３负载量较低时，具有同样的变化规律，并且比相应负载量的ＷＯ３／γ－Ａｌ２Ｏ３样品的还原温度低得多；而当ＷＯ３的负载量超过１７．７％（Ｗ）后，表面ＷＯ３的还原温度反而随着ＷＯ３负载量的增加而逐渐升高。其原因在于经ＴｉＯ２调变的ＴｉＯ３－Ａｌ２Ｏ３载体，Ａｌ２Ｏ３表面的强相互作用中心已优先被ＴｉＯ２占据，从而使低负载量的ＷＯ３／ＴｉＯ２－Ａｌ２Ｏ３样品ＷＯ３的还原温度明显降低；但在高温还原时ＴｉＯ２在由锐钛矿晶型向金红石晶型转化过程中，会对ＷＯ３／ＴｉＯ２Ａｌ２Ｏ３样品表面的ＷＯ３产生很强的包裹作用，从而高负载量的ＷＯ３／ＴｉＯ２－Ａｌ２Ｏ３样品还原温度反而提高。ＴｉＯ２的调变作用存在一个受ＷＯ３负载量制约的最佳范围。
he reduction process of WO3/TiO2-Al2O3 and WO3/Al2O3 catalysts was studied by TPR(Temperature-Programmed-Reduct method. Results show that the reduction temperature ofWO3/TiO2-Al2O3 is much lower than that of WO3/Al2O3 when WO3 load is relatively low. WhenWO3 load is higher than 17. 7% by weight, the reduction temperature of WO3/TiO2-Al2O3samplesbecomes higher with increasing load of WO3. It can be interpreted that TiO2 can change fromanatase to rutile during the process of TPR and has a wrapping effect on WO3 spieces on the surface. It can be concluded that for the load of WO3 on TiO2-Al2O3 surface, there exists an optimumrange of TiO2 content within which the reduction temperature of WO3 can be brought to the lowest ghitit, and where the modulation effect of TiO2 is the greatest.
出处
《石油化工》
CAS
CSCD
北大核心
1996年第1期5-9,共5页
Petrochemical Technology
