碳纳米管的制备及其用于甲醇气相羰基化催化性能

实验发现采用LaFeO3 催化剂乙炔在氢气与氮气气氛中裂解产物完全不同。在反应温度 973K ,氮气气氛下 ,乙炔在催化剂上裂解为碳纳米管 ,平均管径为 30nm ,管径比较均匀 ;在氢气气氛中乙炔主要在热电偶上裂解为碳纤维 ,直径平均为 6 0 0nm左右。采用碳纳米管作催化载体制备的硫化Mo/CNT催化剂 ,比相同条件下碳纤维作载体制得的Mo/CT催化剂甲醇气相羰基化活性高 2～ 3倍 ;在反应温度 5 73K、空速 96 0 0L/kg/h时 ,醋酸甲酯选择性为 76 2 %,此时TOF值最大达到 1 74mol醋酸 /molMo/h。对硫化的Mo/CNT催化剂的TEM图观察发现 ,催化剂颗粒负载在碳纳米管外壁上 ,催化剂颗粒直径平均 10nm。

The preparation of carbon nanotubes and its catalytic performance for methanol vapor-phase carbonylation

The effects of reaction atmosphere (hydrogen or nitrogen) on catalytic decomposition of C 2H 2 were investigated. The results showed that the carbon nanotubes (CNTs) were obtained using LaFeO 3 catalyst in the nitrogen atmosphere at 973 K; and they were multi-walled nanotubes of good quality with average diameter 30 nm. While the carbon fibers (CF) with average diameter 600 nm were obtained in the hydrogen at the same conditions. A novel sulfided Mo/CNTs catalyst has a 2～3 times higher activity for methanol vapor-phase carbonylation than the sulfided Mo/CF catalyst. The carbonylation conditions on the sulfided Mo/CNTs catalyst are optimized as follows: reaction temperature of 573 K and carbon monoxide space velocity of 9600L/kg cat/h. Under the optimum conditions, carbonylation selectivity of 76.2mol% and turnover frequency of 1.74 mol AcOMe/molMo.h are obtained. The morphological structures of the sulfided Mo/CNTs catalyst were examined by TEM. The results indicated that the catalyst particles were supported at the outer walls of carbon nanotubes; and the average diameter of particles was 10 nm.