Catalyst size matters: Tuning the molecular mechanism of the water–gas shift reaction on titanium carbide based compounds

摘要: Abstract The molecular mechanism of the water–gas shift reaction catalyzed by titanium carbide compounds was studied using a density functional approach. Three different catalyst models have been considered: extended TiC(001) surface, Ti 8 C 12 MetCar, and 14 13 nanoparticle. Adsorption reactants, intermediates, products occurs on sites, demonstrating chemical versatility TiC substrates. Thus, adsorption energies depend not only existence low-coordinated but also nature atoms involved in site. two most likely mechanisms, redox associative, were considered. first these mechanisms involves complete water dissociation, whereas second formation carboxyl (OCOH) intermediate. catalytic activity found to be highest for due overly strong reactants either or . This has important consequences underlying chemistry, as evidenced corresponding energy profiles, which show that is preferred route occurring nanoparticles, above surface. However, calculated rate constants indicate will hardly occur former, it quite feasible latter. present study suggests similar transition metal carbides can good catalysts potential substitutes current low-temperature catalysts. In addition, results point possible tuning control particle size steps.