纳米Au/TS-1催化剂的制备及用于甲醇羰基化体系

Preparation of Nano Au/TS-1 Catalyst and Catalytic Performance for the Carbonylation of Methanol

采用负压沉积沉淀法、等体积浸渍法、负压等体积浸渍法等方法制备了纳米Au/TS-1催化剂,研究了深床焙烧和等离子体焙烧,以及焙烧温度和焙烧气氛对催化剂中纳米金粒子大小和催化性能的影响,并采用ICP、TEM、XRD、UV-vis、XPS对催化剂金粒子进行了物化性能表征,采用甲醇羰基化制乙酸甲酯反应表征催化性能.结果表明,不同制备方法、不同焙烧方法、不同焙烧温度和焙烧气氛对负载型纳米Au/TS-1沸石分子筛催化剂中金粒子的大小、形貌、物化性质和催化性能有明显影响.其中,3种制备方法中,氢气气氛下焙烧均比空气和氮气气氛下焙烧得到的催化剂的金粒子尺寸更小,分散更均匀,约为5~10 nm.与其它方法相比,负压沉积沉淀法可制得分散更均匀的金粒子,Au/TS-1沸石催化剂中的金粒子尺寸更小,平均粒径为1~5 nm.催化性能评价结果显示,3种方法制备出的负载型金催化剂用于催化甲醇羰基化制乙酸甲酯反应体系中,甲醇的转化率分别为85%、75%、60%,乙酸甲酯选择性可高达68%,反应温度200℃为最好.

A serial of Au/TS-1 samples were prepared by vacuum deposition precipitation, vacuum impregnation and impregnation methods. The effect of different preparation methods, and calcination atmosphere on the particle size and distribution of gold were considered. Based on characterization of X-ray diffraction, ultraviolet-visible dif- fuse reflectance spectroscopy and transmission electron microscope, it showed that gold particle size of Au/TS- 1 was changed greatly with different preparation methods. Gold particle size （about 1 -5 nm） of 0.89Au/TS-1 prepared by vacuum deposition precipitation was obviously smaller than that of the other preparation methods. Taken Au/TS- 1 catalyst prepared by vacuum deposition precipitation as an example, calcination at HE atmosphere were favorable to the dispersion of gold particles. The activities and carbonylation selectivities of CH3OH and CO on Au/TS-1 cat- alysts were evaluated by a micro-fixed pulse reactor. Results showed that the conversion of CH3OH was above 85 %, 75 % and 60% on the three catalysts, respectively and that the selectivity of methyl acetate could reach 70% on the 0.89Au/TS-1 catalysts at reaction temperature of 200℃.