物理化学学报 >> 2009, Vol. 25 >> Issue (03): 539-544.doi: 10.3866/PKU.WHXB20090323

研究论文 上一篇    下一篇

具有多级孔结构的NH4-β沸石的直接合成及其性能

陈然 巩雁军 李强 窦涛 赵震 徐庆虎   

  1. 中国石油大学(北京)CNPC 催化重点实验室, 北京 102249
  • 收稿日期:2008-10-29 修回日期:2008-12-22 发布日期:2009-03-02
  • 通讯作者: 窦涛 E-mail:doutao@cup.edu.cn

Direct Synthesis and Characteristics of NH4-βZeolite with Hierarchical Pore Structure

 CHEN Ran, GONG Yan-Jun, LI Qiang, DOU Tao, ZHAO Zhen, XU Qing-Hu   

  1. China National PetroleumCorporation, Key Laboratory of Catalysis , China University of Petroleum, Beijing 102249, P. R. China
  • Received:2008-10-29 Revised:2008-12-22 Published:2009-03-02
  • Contact: DOU Tao E-mail:doutao@cup.edu.cn

摘要:

以非离子表面活性剂壬基酚聚氧乙烯醚(TX-15)为模板, 设计氟化铵作为矿化剂, 在近中性条件下直接合成了具有微孔-介孔复合孔道的铵型β沸石. 合成样品采用粉末X射线衍射(PXRD), 高分辨扫描电子显微镜(SEM), 微分热重(DTG)以及氨程序升温脱附(NH3-TPD)等手段进行了表征. 结果表明, 氟离子及非离子表面活性剂的加入对沸石的孔结构、酸性质均起到了一定的调变作用.该沸石具有发达的呈梯级分布的多级孔结构, 孔容高达0.67 cm3·g-1, 且具有较强的Bronsted酸和适度分布的Lewis酸, 大大改善了反应物和产物分子的扩散和反应性能. 在混合C4烃的催化裂解反应中, 该沸石与传统方法合成的β沸石相比, 其转化率提高了约15%, 烯烃(乙烯和丙烯)产率提高了近10%, 芳烃(苯和甲苯)产率提高了3%.

关键词: NH4-β沸石, 多级孔结构, 混合C4烃, 催化裂解, 氟矿化体系

Abstract:

NH4-βzeolite with hierarchical porous structure was directly prepared in a nearly neutral synthetic systemusing nonionic compound (polyoxyethylene nonyl phenylether) as the mesoporogen and fluoride as a mineralizer. Samples were characterized by powder X-ray diffractometry (PXRD), scanning electron microscopy (SEM), NH3-temprature programmed desorption (NH3-TPD), N2 adsorption/desorption and differential thermogravimetry (DTG). N2 analysis results showed that the synthesized H-(NH4)-βzeolite contained stepwise distributed micro-mesoporous structure. The Barrett-Joyner-Halenda (BJH) method of analyzing the N2 adsorption isothermshowed that the mesopore volume was 0.67 cm3·g-1 and the most probable pore size was about 21.8 nm. This value was higher than that for the conventional H-βzeolite (0.37 cm3·g-1 and 3.8 nm). The large amount of Lewis acid and the moderate amount of Bronsted acid in the H-(NH4)-β zeolite was examined by means of Pyridine-IR spectroscopy. Compared to conventional H-βzeolite, the conversion in the catalytic cracking reaction of mixed C4 hydrocarbons using this H-(NH4)-βzeolite was improved by 15%. Yields for the olefins (ethene and propene) and aromatic hydrocarbons (benzene and toluene) increased by 10%and 3%, respectively.

Key words: NH4-βzeolite, Hierarchical porous structure, C4 alkane mixture, Catalytic cracking, Fluoride mineralizer

MSC2000: 

  • O647