Increasing resolution of selectivity in alkene hydrogenation via diffusion length in core-shell MFI zeolite

Xicheng Jia, Yanghwan Jeong, Hionsuck Baik, Jungkyu Choi, Alex C.K. Yip

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

We designed a core-shell zeolite structure comprises of palladium-deposited ZSM-5 core and silicalite-1 (S-1) shell which favors selectivity towards light olefin in hydrogenation via increased diffusion length. A well designed S-1/Pd/ZSM-5 core-shell structure was prepared via secondary crystallization of S-1 layer on the Pd/ZSM-5 core. The catalytic and selectivity performance of the S-1/Pd/ZSM-5 composite was evaluated in catalytic hydrogenation of alkenes in liquid phase. The synthesized S-1/Pd/ZSM-5 gives a much higher selectivity towards 1-hexene (87%) over cyclohexene (13%) even though both reactants are able to enter the 10-membered ring channels of the core-shell structure. The zeolitic core-shell composite also showed an increasing selectivity towards 1-hexene over 1-heptene as the S-1 layers built up, even though both are linear alkenes with similar kinetic diameter that are accessible to the MFI framework. In this work, we demonstrate a strong correlation between the thickness of the S-1 shell layer and the selectivity towards light olefins due to faster mass transfer rate. The design of the core-shell MFI structure is a new example of how selectivity in a zeolite-catalyzed reaction can be changed and enhanced without relying on typical molecular size exclusion process.

Original languageEnglish
JournalCatalysis Today
DOIs
Publication statusAccepted/In press - 2018 Jan 1

Keywords

  • Alkene hydrogenation
  • Core-shell structure
  • Diffusion length
  • MFI zeolite
  • Zeolite selectivity

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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