Enhanced Long-term Stability and Carbon Resistance of Ni/MnxOy-Al2O3 Catalyst in Near-equilibrium CO2 Reforming of Methane for Syngas Production

Baya Djebarri  –  Department of Chemistry, Faculty of Sciences, University of M’hamed Bougara, Algeria
*Fouzia Touahra  –  Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques (CRAPC), Algeria 
Nadia Aider  –  Département de Chimie, Faculté des Sciences, Université Mouloud Mammeri de Tizi Ouzou, Algeria
Ferroudja Bali  –  Laboratory of Natural Gas Chemistry, Faculty of Chemistry, Université des sciences et de la Technologie Houari-Boumediene, Algeria
Moussa Sehailia  –  Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques (CRAPC), Algeria
Redouane Chebout  –  Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques (CRAPC), Algeria
Khaldoun Bachari  –  Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques (CRAPC), Algeria
Djamila Halliche  –  Laboratory of Natural Gas Chemistry, Faculty of Chemistry, Université des sciences et de la Technologie Houari-Boumediene, Algeria Received: 1 Jan 2020; Revised: 6 Mar 2020; Accepted: 13 Mar 2020; Published: 1 Aug 2020; Available online: 30 Jul 2020.

Bulletin of Chemical Reaction Engineering & Catalysis (BCREC)

Abstract

Herein we study the catalytic activity/stability of a new generation of cheap and readily available Ni and Al-based catalysts using two Mn precursors, namely Mn(NO₃)₂ and Mn(EDTA)^2- complex in the reaction of CO₂ reforming of methane. In this respect, Ni/Al₂O₃ and two types of Ni/Mn_xO_y-Al₂O₃ catalysts were successfully synthesized and characterized using various analytical techniques: TGA, ICP, XRD, BET, FTIR, TPR-H₂, SEM-EDX, TEM, XPS and TPO-O₂. Utilization of Mn(EDTA)^2- as synthetic precursor successfully furnished Ni/Al₂O₃-Mn_xO_yY (Y = EDTA) catalyst which was more active during CO₂ reforming of methane when compared to Ni/Mn_xO_y-Al₂O₃ catalyst, synthesized using Mn(NO₃)₂ precursor. Compared to Ni/Mn_xO_y-Al₂O₃, Ni/Al₂O₃-Mn_xO_yY catalyst afforded near-equilibrium conversion values at 700 °C (ca. 95% conversion for CH₄ and CO₂, and H₂/CO = 0.99 over 50 h reaction time). Also, Ni/Al₂O₃-Mn_xO_yY showed more resistance to carbon formation and sintering; interestingly, after 50 h reaction time, the size of Ni⁰ particles in Ni/Mn_xO_y-Al₂O₃ almost doubled while that of Ni/Al₂O₃-Mn_xO_yY remained unchanged. The elevated conversion of CO₂ and CH₄ in conjunction with the observed low carbon deposition on the surface of our best catalyst (Ni/Al₂O₃-Mn_xO_yY) indicated the presence of Mn_xO_y oxide positioning mediated simultaneous in-situ carbon elimination with subsequent generation of oxygen vacant sites on the surface for more CO₂ adsorption. Copyright © 2020 BCREC Group. All rights reserved

Keywords: MnxOy; Al2O3; CO2 reforming of methane; carbon resistance