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

Research output: Contribution to journalArticlepeer-review

1 Citation (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

Keywords

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

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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