Revealing the dependence of CO₂ activation on hydrogen dissociation ability over supported nickel catalysts

Abstract

In the present work, we demonstrate that the mechanism and kinetics of CO 2 activation, as the first step of its hydrogenation, over supported nickel catalysts is particle size sensitive owing to the distinct H 2 dissociation ability over nickel particles with various sizes. Large nickel nanoparticles facilitate H 2 dissociation, enabling CO 2 activation via a kinetically favored redox mechanism compared to small nickel nanoparticles that activate CO 2 via the formate mechanism. The elucidation of the dependency of the catalytic reaction pathway on particle size will guide the rational design of supported nickel catalysts for selective CO 2 hydrogenation. This work demonstrated in the CO 2 hydrogenation reaction, CO 2 is activated through different mechanisms due to different H 2 dissociation capabilities over supported Ni catalysts with different particle sizes, which provides a convincing experimental explanation for the structural sensitivity of nickel-based catalysts.

Combined In Situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Kinetic Studies on CO2 Methanation Reaction over Ni/Al2O3

“…For the fresh 40NiAl catalyst (Figure a), the reduction peak shifts to lower temperatures with a T p of 410 °C and an onset temperature of 271 °C. Such a shift has been previously ascribed to possessing larger nickel nanoparticles and improved hydrogen dissociation ability for 40NiAl than 10NiAl . The content of reduced Ni species in Ni/Al 2 O 3 is quantified using CuO as an external standard.…”

Interface-Enhanced Oxygen Vacancies of CoCuOx Catalysts In Situ Grown on Monolithic Cu Foam for VOC Catalytic Oxidation

“…56,57 The bands at1441 and 1528 cm −1 could be assigned to carbonate [ν s (CO 3 − )] and bicarbonate [ν a (CO)] species due to the interaction of adsorbed CO 2 with H*. 56,58,59 This demonstrated that acetone is degraded to formic acid first and then formic acid is decomposed to carbonate and bicarbonate species on 12CoCu-R. Finally, CO 2 and H 2 O are formed through complete oxidation.…”

Effect of Fe and La on the Performance of NiMgAl HT-Derived Catalysts in the Methanation of CO2 and Biogas

“…The incomplete reduction of Ni 2+ to Ni 0 at 600 °C could explain the low CO 2 conversion and poor productivity below 375 °C. A higher number of Ni 0 sites after reduction at 750 °C may increase both the activation of CO 2 by the dissociative mechanism and the H 2 splitting and, therefore, the CH 4 productivity . Hence, the following Mg-containing catalysts are prereduced in situ at 750 °C.…”