Fe助剂对CuO/Al_2O_3催化剂上CO_2+H_2合成甲醇影响的研究

The Promotion Effect of Fe on CuO/Al_2O_3 Catalyst for the Synthesis of Methanol from CO_2+H_2

在363～873K的温度范围内,0.1MPa的压力下,研究了不同前驱态的铁助剂对CuO/Al2O3催化剂上CO2+H2合成甲醇的影响,对这些催化剂用XRD和TPR方法进行了表征,研究结果表明,在本实验条件下,CuO/Al2O3催化剂上生成甲醇的活性与其上的晶相铜无直接的联系,与催化剂低温活性直接相关的是在室温下能被空气氧化、也可在室温下被还原的高度分散的铜物种;Fe助剂能明显地改变CuO/Al2O3催化剂中Cu的分布、分散度和价态,能增加这些铜物种的含量,从而提高催化剂在CO2+H2合成甲醇反应的低温活性。

<Abstrcat> The effect of Fe promoters in different precursor state on the performance of CuO/Al_2O_3 is studied by means of activity measurement, XRD and temperature-programmed reduction. It is found that the catalytic activity of the catalysts containing Fe promoter obviously increased below 500K, and among the catalysts containing Fe, the catalytic activity of Cat.4 on which the precursor state of Fe promoter is Ⅲ was better than others. Under the conditions used in the present work, it is revealed that highly dispersed Cu species which could be oxidized in air at room temperature and be reduced below 400K is probably responsible for high low temperature activity. Fe promoters could change the distribution, dispersion and chemical state of Cu on Al_2O_3, and favor the formation of the above Cu species, and then enhance the activity of the catalyst at low temperature.