Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (03): 216-220.doi: 10.3866/PKU.WHXB20030306

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Skeletal Isomerization of Butene on Si, Zr-substituted Aluminum Phosphate Zeolites

Wang Zhe-Ming;Yan Zi-Feng   

  1. State Key Laboratory for Heavy Oil Processing, CNPC Key Laboratory of Catalysis, University of Petroleum, Dongying 257061
  • Received:2002-05-23 Revised:2002-08-21 Published:2003-03-15
  • Contact: Wang Zhe-Ming E-mail:zfyancat@hdpu.edu.cn

Abstract: Si, Zr-substituted aluminumphosphate zeolites were synthesized by hydrothermal method. XRD data indicated that they bear the same AEL structure with APO-11 zeolite. Of interest is that the crystal shape of SAPO-11 and APO-11 all are sphere-like, while ZAPO-11 exists as bar-like. Simultaneously, the introduction of heteroatoms in APO-11 skeleton could lead to the positive modification of acidity and micropore features. SAPO-11 showed higher acidity and ZAPO-11 possessed less micropore volume. Of special is that SAPO-11 with Si/Al =0.15 is the optimum shape-selective catalyst of skeletal isomerization of butene. The isomerization effect factors, such as butene partial pressure, temperature, were also extensively investigated. Of special is that the inconsistency in concentration changes between product isobutene and by-product, C3 and C5, was continually occurred while the reaction parameters were accordingly changed. It indicated that isobutene is shape-selectively formed via mono-imolecule mechanism, while the by-products C3 and C5 are mainly formed via bimolecular mechanism.

Key words: Heteroatomic substitution, Aluminumphosphate zeolites, Isomerization of butene, Mono-molecular mechanism, Dimolecular mechanism