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Understanding Coke Deposition Vis-à-Vis DRM Activity over Magnesia-Alumina Supported Ni-Fe, Ni-Co, Ni-Ce, and Ni-Sr Catalysts
oleh: Yousef M. Alanazi, Naitik Patel, Anis H. Fakeeha, Jehad Abu-Dahrieh, Ahmed A. Ibrahim, Ahmed E. Abasaeed, Rawesh Kumar, Ahmed Al-Fatesh
Format: | Article |
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Diterbitkan: | MDPI AG 2023-10-01 |
Deskripsi
The catalytic conversion of CH<sub>4</sub> and CO<sub>2</sub> into H<sub>2</sub>-rich syngas is known as the dry reforming of methane (DRM). The dissociation of CH<sub>4</sub> over active sites, coupled with the oxidation or polymerization of CH<sub>4−x</sub> (x = 1–4), plays a crucial role in determining in determining the DRM product yield and coke deposition. Herein, a series of bimetallic-supported catalysts are prepared by the dispersion of Ni-M (M = Ce, Co, Fe, and Sr) over 60 wt% MgO-40 wt% Al<sub>2</sub>O<sub>3</sub> (60Mg40Al) support. Catalysts are tested for DRM and characterized with XRD, surface area and porosity, temperature-programmed reduction/desorption, UV−VIS−Raman spectroscopy, and thermogravimetry. 2.5Ni2.5Sr/60Mg40Al and 2.5Ni2.5Fe/60Mg40Al, and 2.5Ni2.5Ce/60Mg40Al and 2.5Ni2.5Co/60Mg40Al have similar CO<sub>2</sub> interaction profiles. The 2.5Ni2.5Sr/60Mg40Al catalyst nurtures inert-type coke, whereas 2.5Ni2.5Fe/60Mg40Al accelerates the deposition of huge coke, which results in catalytic inferiority. The higher activity over 2.5Ni2.5Ce/60Mg40Al is due to the instant lattice oxygen-endowing capacity for oxidizing coke. Retaining a high DRM activity (54% H<sub>2</sub>-yield) up to 24 h even against a huge coke deposition (weight loss 46%) over 2.5Ni2.5Co/60Mg40Al is due to the timely diffusion of coke far from the active sites or the mounting of active sites over the carbon nanotube.