催化学报

催化学报 ›› 2007, Vol. 28 ›› Issue (1): 73-79.

• 研究论文 • 上一篇    下一篇

镧改性β分子筛上的异丁烯水合醚化复合反应

杨伯伦,路士庆,吴江,王华军   

  1. 西安交通大学化学工程系动力工程多相流国家重点实验室, 陕西西安 710049
  • 收稿日期:2007-01-25 出版日期:2007-01-25 发布日期:2010-08-28

Complex Reactions of Hydration and Etherification of Isobutene over La-Modified β Molecular Sieve

YANG Bolun*, LU Shiqing, WU Jiang, WANG Huajun   

  1. State Key Laboratory of Multiphase Flow in Power Engineering, Department of Chemical Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China
  • Received:2007-01-25 Online:2007-01-25 Published:2010-08-28

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摘要： 采用离子交换法,分别在微波加热和常规加热的条件下,制备了La/β分子筛催化剂,并采用红外光谱、扫描电子显微镜、 X射线衍射与能量色散谱进行了表征. 考察了不同加热条件下所得的改性β分子筛上La的负载量, La在分子筛表面的分散度以及催化剂对乙醇-水-异丁烯体系水合醚化复合反应的催化性能,并分析了反应机理. 与传统加热法相比,微波加热法制得的催化剂上La离子的一次交换度和负载量高,且交换时间大大缩短. La离子的引入使得β分子筛上乙醇与水的转化率提高了10%～20%, 而且随着La负载量的增加,催化剂的活性呈明显的上升趋势. 反应机理的分析表明,上述水合醚化反应主要发生在β分子筛的表面上, B酸位桥接 Al-OH-Si 酸性点可能是主要的反应活性点,并且反应过程经历碳正离子中间体的形成步骤.

关键词: &beta, 分子筛, 镧, 异丁烯, 乙醇, 水, 水合醚化, 微波加热

Abstract: The La/β molecular sieve catalyst was prepared by the ion-exchange method using microwave heating and conventional heating. The catalyst was characterized by infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy. Hydration and etherification reactions of isobutylene with an ethanol-water mixture to produce a fuel mixture were carried out over these catalysts. The effects of the preparation method and La loading on the catalytic performance of La/β catalysts were studied, and the reaction mechanism was proposed. The results indicated that the ion-exchange degree and La loading of the La/β catalyst prepared by the microwave heating method were higher than the one prepared by the conventional heating method, and the ion-exchange time was shorter. The conversion of water and ethanol over the modified La/β molecular sieve catalyst was increased by 10%～20% compared with the unmodified Hβ molecular sieve, and the catalyst activity increased with the La loading. The hydration and the etherification mainly occurred on the external surface of the β molecular sieve catalyst. Bridging Al[KG-45x]-[KG-20x]OH[KG-45x]-[KG-20x]Si acid sites, i.e., Bronsted acid sites, were the main active sites, and the carbonium ion was formed during the reaction.

Key words: &beta, molecular sieve, lanthanum, isobutene, ethanol, water, hydration etherification, microwave heating