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

Año: 2017

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 a Carberry-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 assess isotopeeffects. For Cu/ZrO⁠2, the initial RWGS reaction rate using D⁠2 instead of H⁠2 was slightly higher whereas suchrate was about equal for the ternary catalyst.Kinetic rate expressions obtained from the Langmuir-Hinshelwood-Hougen-Watson formalism were used tomodel and analyze the experimental results and the reaction mechanism(s) of the RWGS on these catalysts. Congruencewas found between the experimental results and a reaction mechanism where (predominantly) CO⁠2 adsorbsdissociatively on the Cu particles (rate-determining step). The reduction of (ad)oxygen and surface hydroxylsfollow afterwards.