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将Ag-Rh浸渍到共沉淀法合成的Ce-Zr-Al上,制备出Ag(0.04)-Rh(x)/Ce0.5Zr0.5O2-75%Al2O3系列催化剂,采用BET比表面积、X射线衍射光谱(XRD)和原位漫反射傅里叶变换红外光谱(DRIFTS)对催化剂进行表征,并探讨催化剂在贫燃条件下选择性还原NO的活性和反应机理.结果表明,Ag-Rh双组分催化剂的活性较单组分Ag、Rh催化剂的高.Rh负载量为0.7%(质量分数)时,NO转化率达最佳(90.3%),且反应的起燃温度低、活性温度范围宽(300～500℃).DRIFTS结果显示,Rh的添加不仅有利于催化剂表面NO的吸附,而且能促进Ag催化生成关键反应中间体—CO—NH—,进而显著提高NO的转化率.
Ag (Rh) / Ce0.5Zr0.5O2-75% Al2O3 series catalysts were prepared by impregnating Ag-Rh into Ce-Zr-Al synthesized by coprecipitation method. The BET specific surface area and X-ray diffraction (XRD) and in-situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) were used to characterize the catalyst and the catalytic activity of the catalyst for selectively reducing NO under lean-burn conditions. The results showed that the Ag-Rh two component The catalytic activity of the catalyst is higher than that of the single component Ag and Rh catalysts. The NO conversion reaches the best (90.3%) at an Rh loading of 0.7% (mass fraction), and the reaction has a low onset temperature and a broad active temperature range 300 ~ 500 ℃) .DRIFTS results showed that the addition of Rh was not only beneficial to the adsorption of NO on the catalyst surface, but also promoted the formation of the key reaction intermediate-CO-NH- by Ag catalyzed by Ag, which significantly increased the NO conversion.