制备条件对Ru/Ce_(0.8)Zr_(0.2)O_2催化剂上CO_2甲烷化反应性能的影响

采用均相法制得Ce0.8Zr0.2O2载体,并以其为载体等体积浸渍制得一系列负载型Ru催化剂。在0.1 MPa、GHSV为10000 h-1、H2/CO2为3.5(物质的量比)的条件下,对催化剂进行评价。借助TG-DSC、BET、H2-TPR等技术对所制备的载体和催化剂进行表征,结果表明,500℃焙烧的载体具有适中的比表面积和孔径并形成了Ce-Zr固溶体,与载体形成弱相互作用的Ru能够显著提高催化剂的活性,适宜的还原方式能促进活性组分的均匀分布。采用500℃焙烧的载体浸渍Ru Cl3溶液,干燥后在400℃焙烧,并使用水合肼和H2两次还原后的催化剂活性最高,在290℃时,H2转化率可达到93.57%。

Effect of support calcination temperature on the catalytic properties of Ru/Ce0.8 Zr0.2 O2 for methanation of carbon dioxide

A series of Ru/Ce_0.8Zr_0.2O₂ catalysts were prepared by the impregnation method with Ce_0.8Zr_0.2O₂ homoprecipitated and calcined at different temperatures as supports. The supports and the catalysts were characterized with TG-DSC, BET and H₂-TPR techniques. It was shown that the Ce_0.8Zr_0.2O₂ calcined at 500 ℃ formed Ce-Zr solid solution and had a proper surface area and pore opening and a weak interaction with Ru species, leading to a significant increase in the catalytic activity. A suitable reduction methods promoted distribution of active species. The Ru/Ce_0.8Zr_0.2O₂ prepared with the Ce_0.8Zr_0.2O₂ calcined at 500 ℃ showed high activity after calcination at 400 ℃ and successive reduction with H₂N·NH₂·H₂O and H₂. It gave a H₂ conversion of 93.57%, approaching to the equilibrium value under the conditions of 290 ℃, 0.1 MPa, 10 000 h^-1 and H₂/CO₂ mol ratio of 3.5.