催化学报 ›› 2011, Vol. 32 ›› Issue (11): 1739-1746.DOI: 10.3724/SP.J.1088.2011.10703

• 研究论文 • 上一篇    下一篇

钙改性的 Pd/CeO2-ZrO2-Al2O3 催化剂催化甲醇裂解反应

李雪1, 王晓文2, 赵明1,*, 刘建英1, 龚茂初1, 陈耀强1   

  1. 1四川大学化学学院绿色化学与技术教育部重点实验室, 四川成都 610064; 2四川大学化学工程学院, 四川成都 610065
  • 收稿日期:2011-07-11 修回日期:2011-08-29 出版日期:2011-11-14 发布日期:2015-03-30

Ca-Modified Pd/CeO2-ZrO2-Al2O3 Catalysts for Methanol Decomposition

LI Xue1, WANG Xiaowen2, ZHAO Ming1,*, LIU Jianying1, GONG Maochu1, CHEN Yaoqiang1   

  1. 1Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan, China; 2College of Chemical Engineering, Sichuan University, Chengdu 610065, Sichuan, China
  • Received:2011-07-11 Revised:2011-08-29 Online:2011-11-14 Published:2015-03-30

摘要: 采用共沉淀法制备了未改性的和 Ca 掺杂的 CeO2-ZrO2-Al2O3 样品, 进一步用浸渍法制备了 Pd/CeO2-ZrO2-Al2O3 (Pd/CZA) 和 Pd/ CeO2-ZrO2-Al2O3-CaO (Pd/CZACa) 催化剂. 运用 X 射线衍射、N2 吸附-脱附、储氧量测定、CO 化学吸附、NH3 程序升温脱附、CO2 程序升温脱附、H2 程序升温还原和 X 射线光电子能谱对催化剂进行了表征, 并考察了其催化甲醇裂解反应活性. 结果表明, Ca 的添加使载体酸性位中毒, 弱碱中心数目增加, 从而影响了催化剂上吸附物种的吸附-脱附平衡过程; 同时, 使得金属和载体间相互作用增强, 增加了 Pd 周围的电子密度, 使 Pd 保持在部分氧化状态 Pdδ+ (0 < δ < 2), 进而提高了甲醇催化裂解反应的活性, 使甲醇完全裂解温度降低了 34 °C.

关键词: 钯, 钙, 甲醇裂解, 氧化铈, 氧化锆, 氧化铝

Abstract: CeO2-ZrO2-Al2O3 and CeO2-ZrO2-Al2O3-CaO supports were prepared by the coprecipitation method and were loaded with Pd by impregnation to form Pd/CeO2-ZrO2-Al2O3 (Pd/CZA) and Pd/CeO2-ZrO2-Al2O3-CaO (Pd/CZACa) catalysts. The catalysts were characterized by X-ray diffraction, low temperature N2 adsorption-desorption, oxygen storage capacity, CO chemisorption, NH3 temperature-programmed desorption (NH3-TPD), CO2 temperature-programmed desorption (CO2-TPD), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The catalyst activity for methanol decomposition showed that the Ca modification improved the low-temperature activity of the catalyst, which lowered the complete conversion temperature on 34 oC. NH3-TPD and CO2-TPD showed that the addition of Ca poisoned the acid sites of the support or increased the number of weak basic sites and therefore changed the adsorption-desorption equilibria of the adsorbed species. It also enhanced the metal-support interaction and increased the electronic surroundings of Pd sites, which maintained Pd in a partly oxidized (Pdδ+) state and consequently increased the activity for methanol decomposition according to H2-TPR and XPS measurements.

Key words: palladium, calcium, methanol decomposition, ceria, zirconia, alumina