【摘要】 采用固相法合成系列铬钴复合氧化物催化剂,该催化体系在中低温[(180~300)℃]下具有优异的氨选择性催化氮氧化物还原活性,其中,Cr(0.5)-Cr Ox催化剂在空速50 000 h-1、反应温度200℃和220℃条件下,NOx转化率达100%。采用原位DRIFIS研究催化剂表面吸附物种以及催化机理,在反应温度220℃考察Cr(0.5)-Co Ox催化剂表面NH3与NO的吸附态形式和NH3-SCR反应过程中中间态及其反应机理。结果表明,Cr(0.5)-Cr Ox催化剂上NH3吸附在L酸位,也能吸附在B酸位,但只与气态的NOx反应,生成中间体NH2NO,再进一步反应,最终生成N2与H2O。吸附态的NOx不参与SCR反应,反应遵循Eley-Rideal机理。更多还原

【Abstract】 A series of Cr-Co mixed oxide catalysts was prepared by solid states reaction method,which were used for selective catalytic reduction( SCR) of NOx with NH3 in the presence of excess oxygen at medium-low temperature [( 180 ~ 300) ℃]. The experimental results showed that under the condition of space velocity 50 000 h- 1and reaction temperature 200 ℃ and 220 ℃,NOx conversion reached 100% on Cr( 0. 5)-Co Oxcatalyst. In situ diffuse reflectance infrared transform( DRIFT) spectroscopy was employed for investigating the adsorption species on Cr( 0. 5)-Co Oxcatalyst surface and revealing the reaction mechanism under reaction temperature 220 ℃. Based on the in situ DRIFTS results,it was found that NH3 was adsorbed on Lewis and Brnsted acid sites of Cr( 0. 5)-Cr Oxcatalyst,and then decomposed into-NH2. The gas phase NO could bond with-NH2 and form an intermediate NH2 NO,which could further decompose into N2 and H2O. The adsorbed NOx didn’t participate in the SCR reaction. NH3-SCR reaction on Cr( 0. 5)-Co Oxcatalyst mainly followed the Eley-Rideal mechanism.更多还原