Carbon Dioxide Hydrogenation on Ni(110)

Abstract

We demonstrate that the key step for the reaction of CO 2 with hydrogen on Ni(110) is a change of the activated molecule coordination to the metal surface. At 90 K, CO 2 is negatively charged and chemically bonded via the carbon atom. When the temperature is increased and H approaches, the H-CO 2 complex flips and binds to the surface through the two oxygen atoms, while H binds to the carbon atom, thus yielding formate. We provide the atomic-level description of this process by means of conventional ultrahigh vacuum surface science techniques combined with density functional theory calculations and corroborated by high pressure reactivity tests. Knowledge about the details of the mechanisms involved in this reaction can yield a deeper comprehension of heterogeneous catalytic organic synthesis processes involving carbon dioxide as a reactant. We show why on Ni the CO 2 hydrogenation barrier is remarkably smaller than that on the common Cu metal-based catalyst. Our results provide a possible interpretation of the observed high catalytic activity of NiCu alloys.

CO2 dissociation on Ni(211)

“…Therefore, these processes are possible. This is similar to the case of Ni (1 1 0), where the energy barrier of CO 2 (C 2v symmetry) hydrogenation is 0.17 eV lower than that of dissociation on Ni(1 1 0) with DFT calculations [36]. However, the dissociation barrier of HCOO (11) (1.08 eV) is the highest along the reaction path, the dissociation process will go from 11 back to 3b and then to 8.…”

On the kinetics of the methanation of carbon dioxide on coprecipitated NiAl(O)

“…Of course, further mechanisms could have been formulated comprising COH or HCOO, respectively (cf. [37][38][39][40] …”

Insights into the mechanisms of CO2 methanation on Ni(111) surfaces by density functional theory

“…Bothra et al [62] and Vesselli et al [63] explored the hydrogenation and methanation of CO 2 on Ni(110) surfaces by density functional theory (DFT) calculations. They believe that CO was one of the intermediates in this process by comparison of the energy barrier.…”