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Reversal of methanation-oriented to RWGS-oriented Ni/SiO2 catalysts by the exsolution of Ni2+ confined in silicalite-1.
- Source :
- Green Chemistry; 10/7/2023, Vol. 25 Issue 19, p7582-7597, 16p
- Publication Year :
- 2023
-
Abstract
- Investigation of catalytic hydrogenation of CO<subscript>2</subscript> to CO via the reverse water-gas shift (RWGS) was undertaken using Ni/SiO<subscript>2</subscript>-based catalysts. Among the array of catalysts tested, the Ni/SiO<subscript>2</subscript> catalyst derived from the reduction of silicalite-1-encapsulated, ligand-protected Ni<superscript>2+</superscript> (Ni<subscript>0.2</subscript>@S-1-red) exhibited promising performance. This catalyst demonstrated a CO<subscript>2</subscript> conversion rate approaching the equilibrium conversion of RWGS, a selectivity for CO exceeding 99%, and a high space time yield of CO (9.7 mol gNi <superscript>-1</superscript> h<superscript>-1</superscript>). The outcomes observed can be attributed to several factors, such as the highly dispersed Ni<superscript>0</superscript> and Ni<superscript>δ+</superscript> species, as well as the presence of bridging oxygen of the Ni-O-Si structure, on which CO<subscript>2</subscript> can be adsorbed moderately. The moderately bonded CO<subscript>2</subscript> on Ni<subscript>0.2</subscript>@S-1-red allows for the efficient desorption of its reduced intermediate, i.e. *CO, resulting in the generation of gaseous CO at a rapid rate, consequently preventing its deep hydrogenation to CH<subscript>4</subscript>. Complementary Density Functional Theory (DFT) calculations were performed and revealed that CO molecules have poor adsorption and higher adsorption energy on the Ni@S-1 surface compared to the S<superscript>-1</superscript> surface. This supports the rapid desorption of *CO and the observed high selectivity of CO. Moreover, the structure-activity correlation analysis further supports the claim of Ni<subscript>0.2</subscript>@S-1-red as a promising RWGS catalyst. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14639262
- Volume :
- 25
- Issue :
- 19
- Database :
- Complementary Index
- Journal :
- Green Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 172789828
- Full Text :
- https://doi.org/10.1039/d3gc02399k