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Single-Particle Spectroscopy of Alcohol-to-Olefins over SAPO-34 at Different Reaction Stages: Crystal Accessibility and Hydrocarbons Reactivity

Authors

  • Qingyun Qian,

    1. Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (The Netherlands), Fax: (+31) 30-251-1027
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  • Dr. Javier Ruiz-Martínez,

    Corresponding author
    1. Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (The Netherlands), Fax: (+31) 30-251-1027
    • Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (The Netherlands), Fax: (+31) 30-251-1027

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  • Prof. Mohamed Mokhtar,

    1. Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
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  • Prof. Abdullah M. Asiri,

    1. Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
    2. Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
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  • Prof. Shaeel A. Al-Thabaiti,

    1. Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
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  • Prof. Suliman N. Basahel,

    1. Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
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  • Prof. Dr. Bert M. Weckhuysen

    Corresponding author
    1. Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (The Netherlands), Fax: (+31) 30-251-1027
    • Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (The Netherlands), Fax: (+31) 30-251-1027

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Abstract

In situ synchrotron-based IR and UV/Vis micro-spectroscopy combined with isotopically labeled reactants have been used to identify the different hydrocarbon species formed as well as to assess the activity and accessibility of individual 50 μm-sized SAPO-34 crystals. For the methanol-to-olefins process, two reaction stages can be distinguished. The first involves the formation of methoxy species, protonated dimethyl ether, and polyalkylated benzene (PAB) carbocations, which do not affect the accessibility of the SAPO-34 crystal. In addition, methoxy species are very dynamic during this stage. The second stage is related to the formation of polyaromatic (PA) species concentrated in the outer rim of the crystal, which are bulky and interact with the acid sites and thus alter the overall accessibility of the crystal. In contrast, the ethanol-to-olefins process only consists of one major stage, as the formation of PAB and PA species cannot be separated. Furthermore, the formation of these species is more internal, and coke formation is mainly concentrated in a layer located in the inner part of the SAPO-34 crystal.

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