The Influence of a Second Metal on the Ni/SiC Catalyst for the Methanation of Syngas

Abstract

− The catalytic performance of silicon carbide supported nickel catalysts modified with or without second metal (Co, Cu and Zn) for the methanation of CO has been investigated in a fixed-bed reactor using a feed consisting of 25% CO and 75% H 2 without any diluent gas. It has been found that the introduction of Co species can clearly improve the catalytic activity of Ni/SiC catalyst, whereas the addition of Cu or Zn can result in a significant decrease in the catalytic activity. The characterizations by means of XRD, TEM, XPS, CO-TPD and H 2 -TPR indicate that the addition of Co could decrease the particle size of active metal, increase active sites on the surface of methanation catalyst, improve the chemisorption of CO and enhance the reducibility of methanation catalysts. Additionally, the special interaction between Co species and Ni species is likely favorable for the dissociation of adsorbed CO on the surface of catalyst, and this may also contribute to the high activity of 5Co-Ni/SiC catalyst for CO methanation reaction. For 5Cu-Ni/SiC catalyst and 5Zn-Ni/SiC catalyst, Cu and Zn species could cover partial nickel particles and decrease the chemisorption amount of CO. These could be responsible for the low methanation activity. In addition, a 150h stability test under 2 MPa and 300 o C showed that 5Co-Ni/SiC catalyst was very stable for CO methanation reaction.

Recent advances in methanation catalysts for the production of synthetic natural gas

“…168,169 SiC supported Ni catalysts showed good activity and selectivity in syngas methanation. 28,[170][171][172][173][174] Additionally, Ni/SiC exhibited higher resistance to sintering and carbon deposition and is easier for regeneration than Ni/Al 2 O 3 (ref. 28) and Ni/TiO 2 (ref.…”

Porous Silicon Carbide (SiC): A Chance for Improving Catalysts or Just Another Active-Phase Carrier?

“…The team of Guo and co-workers first reported on the use of SiC-based catalysts for the process. − The authors’ choice was motivated by the inherent thermal properties of the SiC materials, their chemical inertness, and stability under highly exothermic conditions. Indeed, their remarkable thermal conductivity was a key feature for controlling and mitigating the generation of local temperature gradients in correspondence to the metal active sites directly engaged in the CO x activation.…”

“…The authors demonstrated an improvement of performance of their Ni/SiC methanation catalysts when higher metal dispersions and stronger metal–support interactions were realized. In this regard, they showed highly beneficial effects on the reaction performance when bimetallic systems Ni–La or Ni–Co , were prepared and used instead of the monometallic Ni/SiC catalyst for the CO 2 and CO methanation, respectively. In both cases, nickel codoping was claimed to improve the metal dispersion of Ni NPs (catalyst active phase) on the support while creating an ideal electronic microenvironment for a more convenient CO 2 or CO activation and dissociation. , As far as the role of the active-phase carrier is concerned, their study clearly showed the higher stability and CO conversion achieved in long-term methanation runs when a poorly conductive oxide-support (TiO 2 ) was replaced by a thermal conductive SiC (Figure A).…”

“…In this regard, they showed highly beneficial effects on the reaction performance when bimetallic systems Ni–La or Ni–Co , were prepared and used instead of the monometallic Ni/SiC catalyst for the CO 2 and CO methanation, respectively. In both cases, nickel codoping was claimed to improve the metal dispersion of Ni NPs (catalyst active phase) on the support while creating an ideal electronic microenvironment for a more convenient CO 2 or CO activation and dissociation. , As far as the role of the active-phase carrier is concerned, their study clearly showed the higher stability and CO conversion achieved in long-term methanation runs when a poorly conductive oxide-support (TiO 2 ) was replaced by a thermal conductive SiC (Figure A).…”