Al_2O_3-TiO_2复合载体制备及其对催化氧化NO性能研究

Research on the preparation conditions and NO oxidation performance of Al_2O_3-TiO_2

为研究Al_2O_3-TiO_2复合载体制备条件对其结构及性能的影响,同时也考察由它负载的催化剂氧化NO的活性,实验用溶胶凝胶法制备一系列TiO_2包覆比、pH值、包覆次数的Al_2O_3-TiO_2复合载体,借助XRD、BET、SEM等表征手段对复合载体进行表征,在负载10%的金属Mn后对催化剂进行活性评价.结果表明,包覆比为1/16、pH=3时,NO转化率较高,在300℃时达到63%,此条件下TiO_2包覆在Al2O3表面形成较薄的包覆层,使载体的热稳定性提高,而且较薄包覆层的形成对NO的催化氧化反应有利;包覆次数为2次时,载体的比表面积明显增大,由1次包覆的197.97m2·g-1增加到237.41m2·g-1,可能由于添加了2倍的分散剂PEG,有助于堆积形成新的孔,为金属活性组分提供更多的结合位点,提高使用复合载体催化剂的催化活性.

In order to study the influence of preparation conditions on the structure and performance of Al2O3-TiO2 catalyst support. The Al2O3-TiO2 is prepared in different coating ratio, pH value and coated times by the sol-gel method. Then, the loading 10% Mn catalyst is characterized by means of catalytic activity evaluation, XRD, BET. The results indicated that the catalyst had good activity （the rate of NO conversion is 63% ） when 1/16 TiO2 covered and pH = 3. The TiO2 formed relatively thin layer on the surface of Al2O3 not only improves the thermal stability of the support, but also contributes to the catalytic oxidation of NO. When the cladding is two the surface area of catalyst support increased significantly from 197.97 m2 · g-1to 237.41 m2 · g-1. It may be that the addition of double amount of PEG contributes to the accumulation and formation of new holes. More binding sites for the metal active components are formed to enhance the catalytic activity of the catalyst.