CO2 Hydrogenation over Pt-Containing UiO-67 Zr-MOFs—The Base Case

Abstract

CO2 hydrogenation was carried out over Pt-containing UiO-67 Zr-MOFs at T = 220–280 °C and ambient pressure, with H2/CO2 = 0.2–9 and contact times, τ = 0.004–0.01 gcat×min×ml−1. The catalysts were characterized by XRD, N2 adsorption, FESEM, TEM and HRTEM, dissolution-NMR, CO chemisorption, IR spectroscopy and TGA. A positive correlation was observed between the degree of Pt reduction and CO2 conversion. Contact time variation experiments showed that CO is a primary product of reaction, while CH4 is a secondary product. Testing of catalyst crystals with 0.15 and 2.0 micron crystal size, respectively, revealed no influence of diffusion on the reaction rate. Comparison to a conventional Pt/SiO2 catalyst showed very similar activation energy, with Eapp = 50±3 kJ×mol−1. However, the turn-over frequency over Pt/SiO2 was significantly lower, and Pt/SiO2 did not yield methane as product. The Pt-containing UiO-67 Zr-MOF catalyst showed stable activity during 60 hours testing.