不同制备工艺钒系SCR催化剂理化及催化性能研究

PHYSICOCHEMICAL PROPERTIES AND CATALYTIC ACTIVITY OF VANADIUM CONTAINED SCR CATALYSTS WITH DIFFERENT SYNTHETIC METHODS

本文研究了制备工艺对TiO_2-WO_3-V_2O_5-载体型催化剂理化特性及其在NH_3-SCR反应中催化性能的影响。通过XRD、TG/DTA等分析方法考察了煅烧温度等对催化剂中各组分晶体结构的影响,确定了制备负载型催化剂的最佳煅烧温度为500℃。不同制备工艺催化剂理化性能的对比表明,多步浸渍法不仅提高了锐钛矿型TiO_2向金红石型TiO_2的转变温度,而且使更多的钒氧化物处于较低的价态,有利于提高还原反应的催化性能;催化活性评价试验也表明使用多步浸渍法制备的SCR催化剂具有较高的催化活性和更宽的高活性反应温度窗口。最后考察了反应空速对多步浸渍法所制备催化剂NO_x转化效率的影响,结果表明:随空速的增加,NO_x转化效率逐渐降低。

The influences of the preparation method on the structure and the NH3-SCR catalytic activity of TiO2-WO3-V2O5-support catalysts are studied in details. The crystal structures of the catalysts obtained at different calcination temperature are characterized by XRD, TG/DTA technique, and the results prove that the optimum calcination temperature is 500℃. The prepared method has a significant effect on the catalytic activity of the TiO2-WO5-V2O5 catalysts. The catalyst prepared by repetitious impregnating method exhibits better catalytic activity because of higher conversion temperature of anatase to rutile, the larger content of TiO2 in loading and the more vanadium oxide at lower valency. It is found from the results of the catalytic activity tests that the catalyst prepared by repetitious impregnating method works well in a wide range of reaction temperature. Based on the catalyst prepared by repetitious impregnating method, finally, we investigate its catalytic activity via the space velocity. Experimental results indicate that the removal efficiency of NOx decreases with increase in space velocity.