Carbon Dioxide Hydrogenation on Cu Nanoparticles

Abstract

The reaction mechanism and active sites for CO 2 adsorption during the reverse water-gas shift (RWGS) reaction on silica-supported Cu nanoparticles were investigated. The Cu nanoparticles prepared by an atomic layer epitaxy technique were shown to strongly bind CO 2 molecules, as evidenced by the two main peaks with maxima near 353 (R peak) and 525 K (β peak) observed during temperature-programmed desorption experiments. The high-temperature peak (525 K), which corresponds to CO 2 in the β state, indicates that β-state CO 2 was the dominant species for the RWGS reaction. The values for the activation energy of CO 2 desorption were 33.4 and 74.4 kJ/mol for R-CO 2 and β-CO 2 , respectively. The sites for CO 2 adsorption were different from those for CO adsorption (defect sites and sites with highly dispersed Cu particles). It is likely that CO 2 hydrogenation occurs on a low-index plane. We propose that the mechanism for the RWGS reaction mainly involves formation of formate species.

Recent advances in catalytic hydrogenation of carbon dioxide

“…35,52,53 Chen et al examined desorption energies of CO 2 , active sites, and reaction mechanism of the RWGS reaction on Cu nanoparticles. 54 The Cu nanoparticles strongly bind CO 2 molecules, as evidenced by two main peaks with maxima at 353 K (a peak) and 525 K (b peak) in CO 2 -TPD (temperatureprogrammed desorption of CO 2 ) spectra. b-Type CO 2 is substantiated as the major species for the RWGS reaction.…”

A Brief Review of Carbon Dioxide Hydrogenation to Methanol Over Copper and Iron Based Catalysts

“…According to Tabatabaei et al [36] the intermediate is a bidentate format on Cu, the most stable absorbed species. Chen et al [36][37][38][39][40] suggest that CO is formed from decomposition of format intermediate, deduced from unification of hydrogen (H 2 ) with CO 2 . As well as, Sloczynski et al [41] indicate that CO may be formed from decomposition of methanol, whereas the reverse-water-gas-shift mechanism can explain directly the CO formation as the major by product.…”

Use of CuNi/YSZ and CuNi/SDC Catalysts for the Reverse Water Gas Shift Reaction

“…The adsorbed hydrogen might react with the adsorbed CO 2 at the three-phase (metal-support-gas) boundary, as shown in (10). Alternatively, the hydrogen adsorbed on the metal surface diffuses from the metal surface unto the support surface prior to reacting via (10) (hydrogen spillover).…”

“…Metallic pure Cu catalysts have shown a tendency to deactivate over time when exposed to high temperatures [8][9][10]. Stabilizers have been used in an attempt to improve copper's thermal stability.…”