物理化学学报 >> 2013, Vol. 29 >> Issue (09): 2047-2055.doi: 10.3866/PKU.WHXB201306211

催化和表面科学 上一篇    下一篇

表面助剂改性对Cu/ZnO/Al2O3甲醇合成催化剂性能的影响

郝爱香, 于杨, 陈海波, 毛春鹏, 魏士新, 殷玉圣   

  1. 南化集团研究院, 南京 210048
  • 收稿日期:2013-04-08 修回日期:2013-06-18 发布日期:2013-08-28
  • 通讯作者: 郝爱香 E-mail:haoax.nhgs@sinopec.com
  • 基金资助:

    中国石油化工股份有限公司-煤基合成气专用合成甲醇催化剂放大研究项目(HX-KA12F001202)资助

Effect of Surface Promoters-Modifying on Catalytic Performance of Cu/ZnO/Al2O3 Methanol Synthesis Catalyst

HAO Ai-Xiang, YU Yang, CHEN Hai-Bo, MAO Chun-Peng, WEI Shi-Xin, YIN Yu-Sheng   

  1. Research Institute of Nanjing Chemical Industry Group, Nanjing 210048, P. R. China
  • Received:2013-04-08 Revised:2013-06-18 Published:2013-08-28
  • Contact: HAO Ai-Xiang E-mail:haoax.nhgs@sinopec.com
  • Supported by:

    The project was supported by the China Petroleum& Chemical Corporation on the Manufacture of Catalyst for Methanol Synthesis from Coal-derived Syngas (HX-KA12F001202).

摘要:

采用共沉淀-后浸渍方法制备了表面助剂改性的Cu/ZnO/Al2O3 (CZA)甲醇合成催化剂, 在固定床反应器上以合成气为原料分别考察了三种助剂(Zr、Ba和Mn)对CZA催化剂性能的影响; 以Zr为助剂时反应温度的影响; 并进行了催化稳定性试验. 利用粉末X射线衍射(XRD)、低温氮气吸脱附(N2-sorption)、氧化亚氮(N2O)反应吸附技术、X射线光电子能谱(XPS)、氢气程序升温吸脱附(H2-TPD)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HR-TEM)技术对催化剂进行了表征.结果显示: 以Zr或Ba作为助剂能够明显提高CZA催化剂耐热前后的甲醇时空收率(STY); Mn的引入降低了CZA催化剂的耐热前活性; Zr的引入降低了CZA催化剂最高活性温度点, 增强了CZA催化剂的催化稳定性; 还原态CZA催化剂表面Cu0和ZnO都能吸附活化氢气, Cu0与ZnO的强相互作用有利于提高催化剂的性能, 耐热后催化剂性能的降低归因于Cu晶粒的长大. 在实验和表征结果基础上,提出了CZA催化剂上合成气制甲醇的“双向同步催化反应历程”.

关键词: 助剂, Zr, Ba, Cu/ZnO/Al2O3催化剂, 甲醇合成, 反应历程

Abstract:

Surface promoters-modified Cu/ZnO/Al2O3 (CZA) catalysts were prepared by a coprecipitationpost impregnation method and evaluated in methanol synthesis fromsyngas. The effects of Zr, Ba, and Mn as promoters, the reaction temperature and run time over CZA and Zr-promoted CZA catalysts on catalytic performance were investigated, respectively. The catalysts were characterized by X-ray diffraction (XRD), N2-sorption, reactive N2O sorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of H2 (H2-TPD), scanning electron microscopy (SEM), and high-resolution transmittance electron microscopy (HR-TEM). The results showed that the space-time yield (STY) of methanol can be increased noticeably over the Zr-or Ba-promoted CZA catalyst before and after the heating treatment of the catalysts. The introduction of Mn as a promoter onto the CZA catalyst led to a decrease in the STY of methanol before heating treatment. The introduction of Zr as a promoter onto the CZA catalyst can decrease the temperature at which the STY of methanol reached the highest value and also improve the catalytic stability. A hydrogen molecule can be adsorbed and then activated over Cu0 and ZnO. The strong interaction between Cu0 and ZnO is favorable for improving the catalytic performance of the CZA catalyst. The decrease in catalytic performance after heating treatment of the CZA catalysts is attributed to a growth of Cu0 crystallites. Based on the results of catalytic performance and characterization, a possible "bidirectional but synchronous catalytic reaction course" in methanol synthesis from syngas over a CZA catalyst is proposed.

Key words: Promoter, Zirconium, Barium, Cu/ZnO/Al2O3 catalyst, Methanol synthesis, Reaction course

MSC2000: 

  • O643