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采用共沉淀法分别制备添加淀粉、聚乙二醇(PEG)做分散剂和不添加任何分散剂的3种La-Al_2O_3材料,并利用低温氮气吸附-脱附、X射线衍射(XRD)、氨气程序升温脱附(NH3-TPD)对材料进行了表征。结果表明,添加分散剂能够有效提高材料的织构性能和抗高温老化性能,改善Al_2O_3材料表面的酸中心强度及酸量。3种材料中,添加PEG做分散剂制备的Al2O3材料经1 050℃焙烧10h后具有最大的比表面积(115.9m~2·g~(-1)),孔容为0.37mL·g~(-1)。XRD结果表明添加PEG能有效抑制在高温老化过程中材料晶型向α相转变。分别以经950℃处理后的3种材料为载体,采用浸渍法制备单Pd(Pd载量为0.83wt%)汽车尾气净化催化剂。催化活性测试结果表明,添加分散剂制备的材料能够提高催化活性,其中添加PEG做分散剂的材料制得的新鲜催化剂和老化催化剂均具有较低的起燃温度和完全转化温度。
Three kinds of La-Al 2 O 3 materials with starch, polyethylene glycol (PEG) as dispersant and without any dispersant were prepared by coprecipitation method. The effects of nitrogen adsorption and desorption, X-ray diffraction The gas temperature programmed desorption (NH3-TPD) was used to characterize the material. The results show that the addition of dispersant can effectively improve the texture properties and high temperature aging properties of the material, and improve the acid strength and acidity of the surface of the Al 2 O 3 material. Among the three materials, Al2O3 material prepared by adding PEG as dispersant has the largest specific surface area (115.9m2 · g ~ (-1)) after calcined at 1 050 ℃ for 10h, the pore volume is 0.37mL · g ~ (- 1). XRD results show that the addition of PEG can effectively inhibit the transformation of the crystalline phase to the α phase during the aging process at high temperature. The single Pd (0.83wt% Pd) catalyst for automotive exhaust gas purification was prepared by impregnation method using three kinds of materials treated at 950 ℃ as carrier respectively. The results of the catalytic activity test showed that the materials prepared by adding dispersant can improve the catalytic activity, and the fresh catalyst and aging catalyst prepared by adding PEG as dispersant have lower light-off temperature and complete conversion temperature.