How CO₂ Chemisorption States Affect Hydrogenation Activity

Abstract

Carbon dioxide (CO 2 ) activation and then hydrogenation is an alternative route to achieve the efficient control of CO 2 emission. For activation, the neutral CO 2 molecule is first chemisorbed as carboxylate (CO 2 δ− ) or carbonate (CO 3 2− ) on catalysts, which is an important step. Up to now, the relationship elucidation between CO 2 chemisorption states and hydrogenation activity still lacks of direct experimental evidence. Herein, the model Zn−Cr mixed oxide catalysts were created to fulfill the goal. The chemisorption states and hydrogenation mechanism were carefully identified by in situ DRIFTS experiments. Furthermore, additional characterizations demonstrated that CO 2 chemisorption states depended on surface oxygen concentration and species. Combined with the results of CO 2 hydrogenation experiments, the conclusion that chemisorption state as carboxylate was beneficial for higher hydrogenation activity was concluded.

Copper-ceria solid solution with improved catalytic activity for hydrogenation of CO2 to CH3OH

“…The copper-ceria solid solution samples (CuCeOx-Y) could facilitate the reduction of surface copper oxide species and achieve higher hydrogenation activity by lowering the energy for H2 activation and generating more oxygen vacancies, due to their higher Cu-Ov-Cex fraction than the CuO/CeO2-Y samples [14]. The oxygen vacancies further enhance the H2 reactivity and the CH3OH formation [29,30]. The second factor is related to CO2 activation.…”

Impacts of the Catalyst Structures on CO2 Activation on Catalyst Surfaces

“…The other chemisorbed CO 2 species is the CO 3 2− , which is direct evidence of the transfer of charge from surface oxygen to the CO 2 and a molecule bending to form a [O-CO 2 ] 2− complexes [33].…”

Probing the morphological effects of ReOx/CeO2 catalysts on the CO2 hydrogenation reaction

“…16 We have also investigated the relationship between the CO 2 chemisorption states and the CO 2 hydrogenation activity based on a Zn-Cr mixed-oxide catalyst. 1 The oxygen-deficient catalyst which adsorbed CO 2 as CO 2 δ− showed a higher hydrogenation activity compared to the oxygen-rich catalyst which chemisorbed CO 2 as CO 3 2− . 1 Therefore, it is a reasonable speculation that the reaction intermediates may be the key clues to clarify the morphology-performance relationship.…”

“…1 The oxygen-deficient catalyst which adsorbed CO 2 as CO 2 δ− showed a higher hydrogenation activity compared to the oxygen-rich catalyst which chemisorbed CO 2 as CO 3 2− . 1 Therefore, it is a reasonable speculation that the reaction intermediates may be the key clues to clarify the morphology-performance relationship.…”

“…CO, CH 4 and CH 3 OH, is a promising way not only for CO 2 elimination, but also for sustainable chemical production. [1][2][3][4] CO 2 hydrogenation typically requires the steps of CO 2 activation and H 2 dissociation, followed by stabilizing intermediates for further hydrogenation. 5 It is accepted that the morphology of the catalyst support in the CO 2 hydrogenation reaction exhibits a crucial role in its activity and selectivity.…”