物理化学学报 >> 2012, Vol. 28 >> Issue (06): 14391439-1447..doi: 10.3866/PKU.WHXB201203142

催化和表面科学 上一篇    下一篇

微介孔复合分子筛合成及其在汽车冷启动尾气控制中的应用

张兰, 张振中, 尉继英, 孟弼芳, 江锋, 梁彤祥   

  1. 清华大学核能与新能源技术研究院, 精细陶瓷北京市重点实验室, 北京 100084
  • 收稿日期:2011-12-31 修回日期:2012-03-08 发布日期:2012-05-17
  • 通讯作者: 尉继英 E-mail:weijiying@tsinghua.edu.cn
  • 基金资助:

    国家自然科学基金(21077064)资助项目

Synthesis of Combined Micro-Mesoporous Zeolites and Their Application to Automobile Cold Start Emission Control

ZHANG Lan, ZHANG Zhen-Zhong, WEI Ji-Ying, MENG Bi-Fang, JIANG Feng, LIANG Tong-Xiang   

  1. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing Key Laboratory of Fine Ceramics, Beijing 100084, P. R. China
  • Received:2011-12-31 Revised:2012-03-08 Published:2012-05-17
  • Contact: WEI Ji-Ying E-mail:weijiying@tsinghua.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21077064).

摘要: 分别采用稀溶液和浓溶液双模板剂两步水热合成法, 以二氧化硅微硅粉和铝酸钠为硅源和铝源, 第一步获得β分子筛晶种, 第二步以β分子筛晶种为结构单元组装形成兼具MCM-41 分子筛和β分子筛结构特点的复合型分子筛β/M(其中β是指β分子筛, M是指MCM-41介孔分子筛). 采用X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、氮气吸附(BET)和高分辨透射电镜(HRTEM)对样品的物相结构和微观形貌进行了表征, 并对复合分子筛的合成过程进行了分析. 结果表明: 复合分子筛β/M的形成是微孔β结构和介孔MCM-41 结构的竞争生长过程, β分子筛晶种的晶化时间和晶粒度大小对β/M复合分子筛的结构有重要影响. 此外, 我们以甲苯为探针分子, 比较研究了三类分子筛β/M、MCM-41和β的原样以及经高温水热处理后样品的吸附性能, 结果表明: β/M复合分子筛的热稳定性优于介孔分子筛MCM-41, 其甲苯吸附容量比MCM-41和β分子筛的高, 其中以浓溶液法合成的复合分子筛吸附容量最高.

关键词: 微介孔复合分子筛, 晶化时间, 晶粒度, 甲苯吸附, 汽车冷启动尾气控制

Abstract: Synthesis of micro-mesoporous zeolites β/M (where β and M denote β zeolite and MCM-41 zeolite, respectively) combined with zeolites β and MCM-41 was achieved in the sodium hydroxide system using a two-step hydrothermal treatment method. Sodium aluminate and fume silica were used as the sources of aluminum and silicon, while tetraethylammonium hydroxide (TEAOH) and cetyltrimethylammonium bromide (CTAB) were used as templates for the formation of β crystal seeds and for self-assembling of β crystal seeds into mesoporous zeolites β/M, respectively. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and high resolution transmission electron microscope (HRTEM). Reaction time and particle size of β crystal seeds were found to play an important role in the synthesis of β/M zeolites. When β seeds crystallize in a short time, a pure phase (denoted βM) can result, whose mesoporous structure resembles MCM-41, while long crystallization times can result in a phase mixture of mesoporous βM and microporous β zeolite. Due to the insertion of the secondary building units of β zeolite into the mesoporous wall, the β/M micro-mesoporous combined zeolites showed enhanced toluene adsorption performance and hydrothermal stability.

Key words: Micro-mesoporous combined zeolite, Crystallization time, Grain size, Toluene adsorption, Automobile cold start emission control

MSC2000: 

  • O647.33