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Media type:
E-Article
Title:
Effect of the Ni/Al Ratio on the Performance of NiAl2O4 Spinel-Based Catalysts for Supercritical Methylcyclohexane Catalytic Cracking
Contributor:
Song, Kyoung Ho;
Jeong, Soon Kwan;
Jeong, Byung Hun;
Lee, Kwan-Young;
Kim, Hak Joo
Published:
MDPI AG, 2021
Published in:
Catalysts, 11 (2021) 3, Seite 323
Language:
English
DOI:
10.3390/catal11030323
ISSN:
2073-4344
Origination:
Footnote:
Description:
<jats:p>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 desorption, 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).</jats:p>