物理化学学报 >> 2004, Vol. 20 >> Issue (08): 854-859.doi: 10.3866/PKU.WHXB20040814

研究论文 上一篇    下一篇

水热脱铝ZSM-5/Y复合分子筛的表征和催化裂化性能

陈洪林;申宝剑;潘惠芳   

  1. 石油大学(北京)重质油国家重点实验室,CNPC催化重点实验室,北京 102249
  • 收稿日期:2004-01-19 修回日期:2004-04-07 发布日期:2004-08-15
  • 通讯作者: 申宝剑 E-mail:baojian@bjpeu.edu.cn

Physicochemical and Catalytic Properties of ZSM-5/Y Composite Zeolites Dealuminated by the Steaming

Chen Hong-Lin;Shen Bao-Jian;Pan Hui-Fang   

  1. State Key Laboratory of Heavy Oil Processing, the Key Laboratory of Catalysis of CNPC, and Faculty of Chemical Engineering, University of Petroleum, Beijing 102249
  • Received:2004-01-19 Revised:2004-04-07 Published:2004-08-15
  • Contact: Shen Bao-Jian E-mail:baojian@bjpeu.edu.cn

摘要: ZSM-5/Y是一种通过原位合成方法制备的新型复合分子筛材料,用XRD、IR光谱、N2吸附/脱附等手段,研究了水热处理对ZSM-5/Y物化性质的影响,并以正己烷为原料考察了样品的催化裂化性能.结果表明,与机械混合样品相比,在550 ℃和700 ℃水热处理条件下,复合分子筛中的Y型沸石相具有更好的结晶保留度.复合分子筛的中孔孔径分布范围大于机械混合分子筛,但复合分子筛样品所表现出的中、大孔体积小于相应的机械混合分子筛.吡啶吸附定量IR研究表明,550 ℃水热处理使复合分子筛的B酸量和L酸量减少;而机械混合样品则是B酸量和L酸量变化很小.进一步700 ℃水热处理则使B和L酸量都大量减少.与氢型样品相比,550 ℃脱铝样品的正己烷裂化活性显著增加,700 ℃脱铝后活性明显降低.产物分布的分析表明活性的提高与反应机理的改变有关.

关键词: ZSM-5/Y复合分子筛, 机械混合分子筛, 水热脱铝, 中孔, 酸性, 催化裂化

Abstract: ZSM-5/Y composite zeolite, a new composite material synthesized in situ from NaY gel, was dealuminated by hydrothermal treatment to study the effect of dealumination on physicochemical properties (undertook with XRD, IR spectroscopy, N2 adsorption/desorption) and catalytic activity (in n-hexane cracking). Compared to the mechanical mixtures, Y phases of the composites had better retained crystallinity under steaming at 550 ℃ and 700 ℃.Steaming resulted in the loss of microporosity of the crystalline material but the increase of mesoporous structure (5~30 nm at 550 ℃ and 5~40 nm at 700 ℃).The size of the mesopore distribution of dealuminated composites was larger than the dealuminated mechanical mixtures, but their macro- and mesopore volume was smaller. Quantitative IR studies of pyridine sorption showed Brønsted and Lewis acid sites of the composite after dealuminated at 550 ℃ decreased (mainly the medium strength acid sites).Compared to the hydrogen type zeolite, the catalytic activity of the dealuminated zeolite for n-hexane cracking increased greatly after 550 ℃ dealumination, and then decreased by further dealumination. The analysis of the product distribution showed that the enhanced activity was related to the change of reaction mechanism.

Key words: ZSM-5/Y composite zeolite, Mechanical mixture, Hydrothermal dealumination, Mesopore, Acidity, Catalytic cracking