氮掺杂碳纳米管担载CuCoCe对合成气制低碳醇的催化性能

以三聚氰胺为氮源,控制其与碳纳米管混合比例,经过高温焙烧得到不同氮含量的氮掺杂碳纳米管(xN-CNTs)载体;通过浸渍法制备x N-CNTs担载的CuCoCe催化剂,研究了氮掺杂对其催化合成气制低碳醇性能的影响。采用X射线衍射(XRD)、N_2吸附-脱附、H_2程序升温还原(H_2-TPR)、NH_3程序升温脱附(NH_3-TPD)和X射线光电子能谱(XPS)等表征手段,分析催化剂结构特性,关联了构效关系。结果表明,氮的掺杂量会影响催化剂活性组分Cu的存在状态及分散情况,减少可还原Co物种的数量,降低催化剂表面酸强度及酸量,使得长链烃类的生成受到抑制,总醇选择性明显提高。分析认为,掺杂在碳管上N的形态分布及掺杂量是影响上述因素的关键。

Catalytic performance of CuCoCe supported on nitrogen-doped carbon nanotubes for the synthesis of higher alcohols from syngas

A series of nitrogen-doped carbon nanotubes (xN-CNTs) were obtained by treating the mixture of melamine and carbon nanotubes at high temperature; the CuCoCe catalysts supported on xN-CNTs were then prepared by impregnation method and used in the synthesis of higher alcohols from syngas. The CuCoCe/xN-CNTs catalysts were characterized by XRD, N₂ sorption, H₂-TPR, NH₃-TPD and XPS and the effect of nitrogen content in xN-CNTs on the catalytic performance of CuCoCe/xN-CNTs in the higher alcohols synthesis was investigated. The results show that the content of nitrogen in xN-CNTs has a significant influence on the existence and dispersion of Cu on the CuCoCe/xN-CNTs catalysts; the presence of nitrogen can reduce the number of reducible Co species and lower the acid strength and amount on the catalyst surface, which helps to suppress the long-chain hydrocarbons formation and improve total alcohol selectivity. It is proposed that the morphological distribution and doping amount of nitrogen on the carbon tubes may play a crucial role in enhancing the catalytic performance of CuCoCe/xN-CNTs in the higher alcohols synthesis.