CO2 hydrogenation on Au/TiC, Cu/TiC, and Ni/TiC catalysts: Production of CO, methanol, and methane

Small Au, Cu, and Ni particles in contact with TiC(0 0 1) display a very high activity for the catalytic hydrogenation of CO2. The major product over these catalysts is CO which is produced by the reverse water–gas shift reaction (RWGS, CO2 + H2 → CO + H2O). In the cases of Au/TiC(0 0 1) and Cu/TiC(0 0 1), a substantial amount of methanol is also produced, but no methane is detected. Ni/TiC(0 0 1) produces a mixture of CO, methanol, and methane. The highest catalytic activity is found for small two-dimensional particles or clusters of the admetals in close contact with TiC(0 0 1). The catalytic activity of the supported metals can be orders of magnitude higher than those of Au(1 0 0), Cu(1 0 0), or Ni(1 0 0). Density functional calculations point to HOCO as a key intermediate for the generation of CO through the RWGS, with the production of methanol probably involving the hydrogenation of a HCOO intermediate or the CO generated by the RWGS.