Effect of the ni/al ratio on the performance of nial2o4 spinel-based catalysts for supercritical methylcyclohexane catalytic cracking

Kyoung Ho Song, Soon Kwan Jeong, Byung Hun Jeong, Kwan Young Lee, Hak Joo Kim

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    14 Citations (Scopus)

    Abstract

    Supercritical methylcyclohexane cracking of NiAl2O4 spinel-based catalysts with varying Ni/Al deficiencies was investigated. Thus, catalysts with Ni content of 10–50 wt.% were prepared by typical co-precipitation methods. The calcined, reduced, and spent catalysts were characterized by X-ray diffraction, O2 temperature-programmed oxidation, NH3 temperature-programmed de-sorption, N2 physisorption, O2 chemisorption, scanning and transmission electron microscopy, and X-ray fluorescence. The performance and physicochemical properties of the reference stoichiometric Ni3Al7 catalyst differed significantly from those of the other catalysts. Indeed, the Ni-deficient Ni1Al9 catalyst led to the formation of large Ni particles (diameter: 20 nm) and abundant strong acid sites, without spinel structure formation, owing to the excess Al. These acted with sufficient environment and structure to form the coke precursor nickel carbide, resulting in a pressure drop within 17 min. On the other hand, the additional NiO linked to the NiAl2O4 spinel structure of the Al-deficient Ni5Al5 catalyst formed small crystals (10 nm), owing to the excess Ni, and displayed improved Ni dispersion. Thus, dehydrogenation proceeded effectively, thereby improving the resistance to coke formation. This catalytic behavior further demonstrated the remarkable activity and stability of this catalyst under mild conditions (450 °C and 4 Mpa).

    Original languageEnglish
    Article number323
    Pages (from-to)1-22
    Number of pages22
    JournalCatalysts
    Volume11
    Issue number3
    DOIs
    Publication statusPublished - 2021 Mar

    Bibliographical note

    Publisher Copyright:
    © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

    Keywords

    • Coke formation
    • Dehydrogenation
    • Heat sink
    • Methylcyclohexane
    • NiAl2O4 spinel

    ASJC Scopus subject areas

    • Catalysis
    • Physical and Theoretical Chemistry

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