碳纳米管促进Au/Al_2O_3对甲酸分解的催化研究

Catalysis of Decomposition of Formic Acid by Au/Al_2O_3 Promoted by Carbon Nanotubes

利用碳纳米管(CNTs)作为添加剂,研发出一种高效新型的Au/CNTs-Al2O3催化剂,其对甲酸分解脱氢具有较高催化活性.经过优化后的Au/CNTs-Al2O3催化剂,在甲酸和甲酸钠摩尔比为7∶3的条件下,363K时甲酸分解的转化频率可达356h-1,比没有掺杂CNTs的Au/Al2O3基底催化剂的活性提高了71%,比直接使用CNTs作载体的Au/CNTs催化剂提高了236%.利用气相色谱检测分解后的气体产物,发现其中CO的体积分数小于0.01%,保证了分解得到的氢气的清洁与干净.联合谱学表征结果表明,CNTs的加入不仅增大了载体的比表面积,而且高度分散了催化剂表面Au粒子使其粒径保持在2nm左右,另外还提高了催化剂表面活性物种Au0的比例.同时,CNTs的高吸氢、储氢能力,也有助于活性位上甲酸分子解离下来的氢物种向CNTs溢流、扩散,从而促进了甲酸脱氢的活性.

A type of highly efficient Au/Al2O3 catalyst doped with carbon nanotubes（CNTs）for decomposition of formic acid was developed,which displayed relatively high activity.Using the Au/CNTs-Al2O3 catalyst under the reaction conditions of 363 Kand a mole ratio of formic acid to sodium formate of 7∶3,the turn-over frequency（TOF）of formic acid decomposition reached 365h-1,71% higher than using the Au/Al2O3 catalyst without CNTs and 236% higher than using the Au/CNTs catalyst.We measured the gas products from decomposition of the formic acid by GC-9160 chromatography and found that the fractional volume of CO was less than 0.01%,which ensured the decomposed hydrogen clean and pure.The results of the catalyst characterization demonstrated that the addition of CNTs not only increased the specific surface areas of supporters,highly dispersed Au particles on the surface of the catalyst to around 2nm,but also enhanced the proportion of active species Au0 on the catalyst surface.Meanwhile,CNTs with high hydrogen absorption and hydrogen storage capacity would be conducive to scattering hydrogen-species produced from dehydrogenation of formic acid molecules at the active Au sites and transferring them to the CNTs,followed by diffusion,thus promoting the dehydrogenation of formic acid.