Pd基贵金属催化甲醇合成反应的研究

Study on Pd-based noble metal catalysts for methanol synthesis

采用浸渍法制备了钯基甲醇合成催化剂,考察了Pd负载量和前驱体盐对催化剂性能的影响,结果表明,Pd负载量越大,催化甲醇合成活性越高;用乙酸盐前驱体制得的Pd基催化剂的甲醇合成催化活性最高。在考察的条件范围内,甲醇选择性均高于98%,催化剂热稳定性均为100%。考察了以硅大球、γ-Al_(2)O_(3)、CeO_(2) 为载体的Pd基甲醇合成催化剂性能,结果表明,载体的比表面积和孔径分布对Pd基催化剂的活性具有较大的影响,比表面积越大,适宜孔径分布占比越高,CO转化率越高。以葡萄糖水热合成的介孔氧化铝载体用于制备Pd基甲醇合成催化剂,其CO转化率得到较大提升。考察了4种助剂对Pd基甲醇合成催化剂性能的影响,结果表明,Mg和Ca对提高催化剂的活性有利,Na和Ba的引入不利于提高Pd基甲醇合成催化剂性能,尤其是Na的存在不但会降低催化剂活性,而且也不利于提高甲醇选择性,在催化剂制备过程要尽量避免Na粒子的引入或残留。

Pd-based methanol synthesis catalysts are prepared by impregnation method.The effects of Pd loading and precursor salt on the performance of the catalysts are investigated.The results show that the higher the Pd loading,the higher the catalytic activity for methanol synthesis.The Pd-based catalysts prepared from acetate precursor have the highest catalytic activity for methanol synthesis.In the range of investigated conditions,the methanol selectivity is higher than 98%,and the thermal stability of all catalysts is 100%.The performance of Pd-based methanol synthesis catalysts supported on silicon spheres,γ-Al_(2)O_(3),CeO_(2) is investigated.The results show that the specific surface area and pore size distribution of the support have a great influence on the activity of Pd-based catalysts.The larger the specific surface area,the higher the proportion of suitable pore size distribution,and the higher the CO conversion.The mesoporous alumina supports prepared by glucose hydrothermal synthesis are used to prepare of Pd-based methanol synthesis catalysts,and the CO conversion rate is greatly improved.The effects of four additives on the performance of Pd-based methanol synthesis catalysts are investigated.The results show that Mg and Ca are beneficial to improve the activity of the catalysts,and the introduction of Na and Ba is not conducive to improve the performance of Pd-based methanol synthesis catalysts.In particular,the presence of Na would not only reduce the activity of the catalysts,but also improve the selectivity of methanol.The introduction or residue of Na particles should be avoided in the process of catalysts preparation.