Transient Analysis of the Reverse Water Gas Shift Reaction on Cu/ZrO2 and Ga2O3/Cu/ZrO2 Catalysts

E.L. FORNERO; D.L. CHIAVASSA; A.L. BONIVARDI; M.A. BALTANÁS

Journal of CO2 utilization

Elsevier NV

Lugar: Amsterdam; Año: 2017 vol. 22 p. 289 - 298

2212-9820

The performance of two copper-based catalysts, Cu/ZrO2 and Ga2O3/Cu/ZrO2, in regards the reverse water gasshift (RWGS) reaction as compared with their reaction rates for the methanol synthesis reaction (RCH3OH) wasstudied using H2/CO2 mixtures at 1.6 and 0.1 MPa, at 498 K. The reactivity studies were carried out using aCarberry-type microcatalytic reactor operated in the batch (transient) mode after H2 prereduction at 523 K (2 h).Measurements of the catalytic activity were also made using D2/CO2 mixtures (0.1 MPa, 498 K) to assessisotope effects. For Cu/ZrO2, the initial RWGS reaction rate using D2 instead of H2 was slightly higher whereas such rate was about equal for the ternary catalyst.Kinetic rate expressions obtained from the Langmuir-Hinshelwood-Hougen-Watson formalism were used to model and analyze the experimental results and the reaction mechanism(s) of the RWGS on these catalysts.Congruence was found between the experimental results and a reaction mechanism where (predominantly) CO2 adsorbs dissociatively on the Cu particles (rate-determining step). The reduction of (ad)oxygen and surface hydroxyls follow afterwards.