物理化学学报 >> 2015, Vol. 31 >> Issue (11): 2139-2150.doi: 10.3866/PKU.WHXB201509281

催化和表面科学 上一篇    下一篇

不同模板剂合成具有介微结构的ZSM-5分子筛及其甲醇制丙烯性能

张兰兰,宋宇,李国栋,张少龙,尚蕴山,巩雁军*()   

  • 收稿日期:2015-07-06 发布日期:2015-11-13
  • 通讯作者: 巩雁军 E-mail:gongyj@cup.edu.cn
  • 基金资助:
    国家重点基础研究发展规划项目(973)(2012CB215003);国家自然科学基金项目(21176255, 21276278)

ZSM-5 Zeolite with Micro-Mesoporous Structures Synthesized Using Different Templates for Methanol to Propylene Reaction

Lan-Lan. ZHANG,Yu. SONG,Guo-Dong. LI,Shao-Long. ZHANG,Yun-Shan. SHANG,Yan-Jun. GONG*()   

  • Received:2015-07-06 Published:2015-11-13
  • Contact: Yan-Jun. GONG E-mail:gongyj@cup.edu.cn
  • Supported by:
    the National Key Basic Research Program of China (973)(2012CB215003);National Natural Science Foundationof China(21176255, 21276278)

摘要:

分别采用四丙基氢氧化铵(TPAOH),十六烷基三甲基溴化铵(CTAB)和N-十八烷基-N'-己基-四甲基-1, 6-己二铵(C18-6-6Br2)作为模板剂,合成了具有不同介微结构的纳米ZSM-5分子筛(NZ),介孔ZSM-5分子筛(MZ)和纳米薄层ZSM-5分子筛(NSZ).对合成的样品进行X射线衍射(XRD),扫描电子显微镜(SEM), N2吸附-脱附和氨程序升温脱附(NH3-TPD)表征,并与传统微孔ZSM-5分子筛(CZ)对比.结果表明,样品的介孔孔容和外表面积大小的顺序为NSZ > MZ > NZ > CZ,强/弱酸之比的顺序为CZ > MZ > NZ > NSZ.在甲醇制丙烯(MTP)反应中,催化剂的介微结构特征影响MTP反应的产物选择性及稳定性,丙烯和总低碳烯烃选择性随着介孔孔容的增加而增加, NSZ样品具有最高的丙烯选择性(47.5%)及总低碳烯烃选择性(78.4%).此外,介孔的引入能适当延长催化剂的寿命,具有适宜酸性质的NZ样品的催化寿命最长(200 h).

关键词: ZSM-5分子筛, 纳米, 纳米薄层, 介孔, 甲醇制丙烯

Abstract:

ZSM-5 zeolites with different pore structures were synthesized using different templates (tetrapropyl ammonium hydroxide (TPAOH), cetyltrimethylammonium bromide (CTAB) and C18-6-6Br2). The obtained nanosized (NZ), mesoporous (MZ), and nanosheets (NSZ) ZSM-5 samples were compared with conventional microporous ZSM-5 zeolite (CZ). The physicochemical properties of these samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption, and temperature-programmed desorption of ammonia (NH3-TPD). The results showed that the mesopore volumes and surface areas of the four samples increased in the order NSZ > MZ > NZ > CZ, and the ratio of strong/weak acidity increased in the order CZ > MZ > NZ > NSZ. In the methanol to propylene (MTP) reaction, the catalyst porosity played an important role on the product selectivity and catalytic stability. The selectivities for propylene and total olefins improved with increasing mesoporosity; NSZ, with the largest mesopore volume, gave the highest propylene selectivity, i.e., 47.5%, and 78.4% total olefins. Meanwhile, the introduction of mesopores into the ZSM-5 zeolite extended the catalytic lifetime. The NZ sample displayed reliable MTP catalytic activity for 200 h, which was predominately attributed to its optimal combination of acidity and porosity.

Key words: ZSM-5 zeolite, Nanometer, Nanosheet, Mesopore, Methanol to propylene

MSC2000: 

  • O643