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Pd-Pt双金属基甲烷氧化催化剂的催化活性、抗水热老化性和耐硫性在一个通有模拟稀燃天然气汽车尾气成分的固定床反应器中进行检测.研究发现Zr掺杂的Pd-Pt/Al2O3(Pd-Pt/Zrx Al(1–x)O(3+x)/2)提高了催化的催化活性、抗水热老化性和耐硫性.以共沉淀法制备Zr:Al的摩尔比分别为0:1、0.25:0.75、0.5:0.5、0.75:0.25和1:0的材料为载体材料.双金属催化剂的活性组分分别为1.5%(w,质量分数)的Pd和0.3%(w)的Pt,活性组分Pd、Pt通过共浸渍的方法浸渍到以上载体材料上制备得到一系列整体式催化剂.分别采用低温N2吸脱附、X射线衍射(XRD)、H2程序升温还原(H2-TPR)、O2程序升温氧化(O2-TPD)及X射线光电子能谱对制备的催化剂进行表征.结果显示Zr的加入使催化剂的载体材料结晶度提高,活性组分的分散度也得到了相应的提高.同时二价Pd物种与周围电子密度分别增加.相比于Pd-Pt/Al2O3和Pd-Pt/ZrO2催化剂,在不同条件预处理后,Zr的添加对催化剂的性能有明显的提高,其中催化剂Pd-Pt/Zr0.5Al0.5O1.75展现了最好的催化活性、抗水热老化性以及耐硫性.
The catalytic activity of Pd-Pt bimetallic methane oxidation catalyst, its resistance to hydrothermal aging and sulfur tolerance were tested in a fixed-bed reactor equipped with an exhaust gas component simulating a lean-burn natural gas vehicle. It was found that Zr-doped Pd- Pt / Al2O3 (Pd-Pt / ZrxAl (1-x) O (3 + x) / 2) improves catalytic activity, resistance to thermal aging and sulfur resistance. The molar ratio was 0: 1, 0.25: 0.75, 0.5: 0.5, 0.75: 0.25 and 1: 0, respectively, as the support material.The active components of the bimetallic catalysts were 1.5% (w, mass fraction) A series of monolithic catalysts were prepared by impregnation of Pt, Pt and Pt (active components) on the above support materials by co-impregnation method, and the catalysts were characterized by N2 adsorption and desorption, X-ray diffraction (XRD) (H2-TPR), O2 temperature-programmed oxidation (O2-TPD) and X-ray photoelectron spectroscopy were used to characterize the prepared catalyst. The results showed that the addition of Zr increased the crystallinity of the supported catalyst material and the dispersion of the active ingredient And the electron density of the bivalent Pd species and the surrounding electron density increased respectively.Compared with the Pd-Pt / Al2O3 and Pd-Pt / ZrO2 catalysts , Under different conditions pretreatment, the addition of Zr on the performance of the catalyst has been significantly improved, in which the catalyst Pd-Pt / Zr0.5Al0.5O1.75 exhibits the best catalytic activity, resistance to hydrothermal aging and sulfur resistance .