钛铝比对溶胶凝胶法制CuZnAlTi催化剂结构和性能的影响

Influence of Ti/Al molar ratio on the structure and performance of CuZnAlTi catalyst prepared by sol-gel method

采用溶胶凝胶法制备了一系列Cu Zn Al Ti催化剂,采用X射线粉末衍射、N2吸附、H_2程序升温还原、NH_3程序升温脱附等方法对催化剂进行了表征,并将催化剂用于固定床CO加氢催化反应中,考察了钛铝比对催化剂结构和性能的影响。结果表明,催化剂中Al和Ti组分均以无定形或高度分散的形式存在;在Cu Zn Al催化剂中引入Ti组元,可以提高催化剂中Cu O的分散度和催化剂的表面积和表面酸含量,减小催化剂的平均孔径,降低催化剂中Cu O的被还原能力,从而改变了催化剂上CO加氢反应的产物分布。随着Ti/Al比增加,催化剂中Cu O晶粒和平均孔径呈现先减小后增大的趋势,而催化剂的比表面积和还原峰顶温度呈现先升后降的趋势,CO转化率与Ti/Al比间没有一定的顺变关系。

A series of CuZnAlTi catalysts were prepared by sol-gel method and characterized by X-ray diffraction,N2-adsorption,H2 temperature-programmed reduction and NH3temperature-programmed desorption. The catalytic performance of CO hydrogenation of catalyst was evaluated in a fixed bed reactor. The effects of Al/Ti molar ratio on the catalysts’ structure and performance were investigated. Al and Ti in the catalyst were in the form of amorphous or highly fragmented. After Ti was introduced to CuZnAl catalyst,the dispersion of CuO,surface area and the amount of surface acid increased,while the average pore diameter decreased,and the reduction ability of CuO in the catalyst was weakened, therefore the product distribution of the CO hydrogenation reaction was changed accordingly. With the increase of Ti/Al ratio,the size of CuO grain and the average pore diameter in the catalyst showed a tendency of increasing firstly but decreasing subsequently,while the specific surface area and reduction peak temperature of the catalyst show an opposite tendency,and the conversion of CO showed no certain corresponding relationship with Ti/Al ratio.