金属助剂对合成气制高碳醇Co/AC催化剂性能影响

Effect of metal promoters on catalytic performance of Co/AC for higher alcohols synthesis from syngas

本实验考察了不同金属助剂(Mn、Zn、La和Zr)对活性炭负载的Co基催化剂(Co/AC)在合成气转化中的活性和产物选择性调控的影响。结果表明,这些金属助剂对CO解离速率,Co_(2)C生成以及醇类产物选择性都有明显的促进作用。所构筑的Co_(2)C/Co^(0)构成了高碳醇合成所需的双活性位结构。其中,Zn修饰的Co/AC催化剂表现出最强的CO解离速率、最高的活性和醇类产物的时空收率。Mn助剂最有利于Co_(2)C的生成,但过高的Co_(2)C/Co^(0)比例导致活性略有下降。Zr和La助剂修饰的催化剂具有相似的CO解离速率和催化活性,但CoZr/AC催化剂适宜的Co_(2)C/Co^(0)比及界面环境更有利于实现CO解离和CO非解离功能的协同,从而表现出最高的醇产物选择性。

Shifting products of Fischer-Tropsch Synthesis(FTS)from paraffins to value-added higher alcohols receives great attention but remains great challenge.Herein,metal oxides of Mn,Zn,La and Zr are investigated as promoters to tune the activity and product distributions of Co/AC catalyst for syngas conversion.It is found that these promoters show different 0 promotion effect on CO dissociation rate,the formation of Co_(2)C phase and the alcohols selectivity.The formed Co_(2)C/Co^(0) constitutes the dual active site for higher alcohols synthesis.The strongest CO dissociation rate is observed for Zn-promoted Co/AC catalyst,resulting in the highest activity and space-time yield(STY)of alcohols.The Mn promoter is most conducive to the formation of Co2C,but slightly decreases the activity.The similar CO dissociation rate and CO conversion are obtained over both Zr-and La-promoted Co/AC catalysts,but the Zr-promoted Co/AC catalyst exhibits the highest alcohols selectivity due to the function balance between CO non-dissociative insertion and CO dissociation.