物理化学学报 >> 2012, Vol. 28 >> Issue (11): 2705-2712.doi: 10.3866/PKU.WHXB201207171

催化和表面科学 上一篇    下一篇

氟硅酸铵改性纳米HZSM-5分子筛催化甲醇制丙烯

胡思1, 张卿1, 夏至2, 巩雁军1, 徐君3, 邓风3, 窦涛1,2   

  1. 1 中国石油大学(北京)中国石油天然气集团公司催化重点实验室, 北京 102249;
    2 太原理工大学精细化工研究所, 太原 030024;
    3 中国科学院武汉物理与数学研究所, 武汉 430071
  • 收稿日期:2012-05-25 修回日期:2012-07-17 发布日期:2012-10-17
  • 通讯作者: 巩雁军,窦涛 E-mail:doutao@cup.edu.cn;gongyj@cup.edu.cn
  • 基金资助:

    国家重点基础研究发展计划(973)项目(2012CB215002), 国家自然科学基金(10979076, 21176255), 国际科技合作与交流专项项目(2010DFB40440)资助

Catalytic Conversion of Methanol to Propylene over (NH4)2SiF6-Modified Nanosized HZSM-5 Zeolite

HU Si1, ZHANG Qing1, XIA Zhi2, GONG Yan-Jun1, XU Jun3, DENG Feng3, DOU Tao1,2   

  1. 1 The Key Laboratory of Catalysis of CNPC, China University of Petroleum-Beijing, Beijing 102249, P. R. China;
    2 Institute of Special Chemicals, Taiyuan University of Technology, Taiyuan 030024, P. R. China;
    3 Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
  • Received:2012-05-25 Revised:2012-07-17 Published:2012-10-17
  • Supported by:

    The project was supported by the State Key Development Program for Basic Research of China (973) (2012CB215002), National Natural Science Foundation of China (10979076, 21176255), and International Science and Technology Cooperation and Exchange Program of China (2010DFB40440).

摘要:

在静态条件下, 采用不同浓度的氟硅酸铵溶液对纳米ZSM-5分子筛进行了改性处理. 利用粉末X射线衍射(XRD)、27Al 魔角旋转固体核磁共振(27Al MAS NMR)、X射线荧光光谱(XRF)、X射线光电子能谱(XPS)、N2 吸附、透射电镜(TEM)、NH3程序升温脱附(NH3-TPD)、吡啶吸附红外光谱(Py-IR)等技术对改性前后纳米ZSM-5分子筛的骨架结构、织构性质、酸性质进行了表征. 并在常压、反应温度为450℃、甲醇质量空速(WHSV)为1 h-1的条件下, 研究了改性前后纳米HZSM- 的甲醇制丙烯(MTP)催化性能. 结果表明, 合适浓度的氟硅酸铵处 理能够选择性地脱除纳米ZSM-5 分子筛的外表面铝, 从而使得HZSM-5 的酸密度降低, 比表面积和孔容增大, MTP催化性能显著提高. 氟硅酸铵改性后纳米HZSM-5 的丙烯选择性和丙烯/乙烯(P/E)质量比分别由原来的 28.8%和2.6提高到45.1%和8.0, 催化剂寿命增加了近2倍.

关键词: 纳米ZSM-5, 脱铝, 孔结构, 酸性, 丙烯选择性, 催化寿命

Abstract:

(NH4)2SiF6-modified nanosized HZSM-5 zeolite was prepared and investigated as a catalyst formethanol to propylene conversion. The effects of this modification on the framework, textural propertiesand acidity of both the parent and the modified HZSM-5 zeolite were investigated by powder X-raydiffraction (XRD), 27Al magic angle spinning nuclear magnetic resonance (27Al MAS NMR), X-rayfluorescence (XRF), X-ray photoelectron spectroscopy (XPS), N2 adsorption, transmission electronmicroscopy (TEM), temperature-programmed desorption of ammonia (NH3-TPD), and infraredspectroscopy of adsorbed pyridine (Py-IR). The catalytic performance of these materials on the methanolto propylene (MTP) conversion process was tested under operating conditions of T=450℃, p=0.1 MPa(pMeOH=50 KPa) and WHSV=1 h-1. The results showed that surface aluminum on the nanosized ZSM-5zeolite could be selectively removed by the (NH4)2SiF6 solution and that the number of acidic sites on theHZSM-5 zeolite gradually decreased with increasing (NH4)2SiF6 concentration. Moreover, after modification with an optimally concentrated (NH4)2SiF6 solution, an obvious increase in specific surface area as well asmesopore volume was observed for the nanosized HZSM-5 with a resulting dramatic improvement in thecatalytic performance of this material for the MTP reaction. Both the propylene selectivity and propylene/ethylene (P/E) mass ratio resulting from use of the modified HZSM-5 increased significantly to 45.1% and8.0, as compared to results of 28.8% and 2.6 obtained with the original material. In addition, the catalyticlifespan of the modified zeolite was double that of the original.

Key words: Nanosized ZSM-5, Dealumination, Pore structure, Acidity, Propylene selectivity, Catalytic lifetime

MSC2000: 

  • O643.3