柠檬酸对WP催化剂噻吩加氢脱硫性能影响

Effect of Citric Acid on Hydrodesulfurization Activities of Thiophene for Tungsten Phosphide Catalysts

以柠檬酸(CA)为助剂,采用共浸渍和程序升温还原的方法制备了不同n(CA)/n(WP)的WP催化剂。并用X射线衍射(XRD)、比表面积测定(BET)、扫描电镜(SEM)、热重(TG)分析等方法对催化剂进行了表征,通过高压微反评价了催化剂的噻吩加氢脱硫(HDS)性能。结果表明,柠檬酸并没有改变WP的本体结构,但具有阻止WP晶相颗粒生长的作用,并提高了WP催化剂的BET比表面积。加入柠檬酸改变了硝酸根的分解过程,降低了催化剂的起始磷化还原温度和磷化还原过程终结温度,有利于活性组分在催化剂表面的分散。柠檬酸对WP催化剂噻吩HDS反应有利。Cat-5催化剂具有相对最好的HDS活性,与不加柠檬酸的催化剂相比,其噻吩转化率提高近20.4%。

Citric acid（CA） as additive, WP catalysts with different molar ratio for citric acid（CA） to WP were prepared by inimpregnation and temperature programmed reduction（TPR） method. The catalysts were characterized by X-diffraction（XRD）, BET surface area, scanning electron microscope （SEM） and thermal g ravimetric/differential thermal （TG） methods. The thiophene hydrodesulfurization（HDS） activities of WP catalysts were evaluated through a micro-high press reactor. The results indicate that WP bulk structure is not changed by addition of CA, while the WP crystal particle growth is inhibited and the BET surface area is improved. It is possible that the process of nitrate radical decomposition is moved and the initial temperature and end temperature is deduced by addition of CA and resulting in the active species of WP is well dispersed to the catalysts surface. Catalyst with CA possessed higher thiophene HDS activities. The Cat-5 catalyst show the highest HDS activity and it gave HDS conversion of 20.4 % higher than that without CA.