Ga and Zn increase the oxygen affinity of Cu-based catalysts for the CO_x hydrogenation according to ab initio atomistic thermodynamics

Abstract

In this article, we show that the surface state of Cu-based COx-hydrogenation catalysts with reducible promoters depends on the composition of the active atmosphere, and the surface becomes highly dynamic only for CO2-containing feeds.

Structure and Role of a Ga-Promoter in Ni-Based Catalysts for the Selective Hydrogenation of CO2 to Methanol

“…These results indicated that the Ni–Ga alloy nanoparticles retained their structure and composition under CO 2 hydrogenation conditions, with no evidence for dealloying/additional alloying, in agreement with the study of Hejral et al using unsupported Ni–Ga nanoparticles . The behavior observed for Ni–Ga/SiO 2 contrasts what have been observed for other bimetallic catalysts (i.e., Cu–Zn, Cu–Ga, , Pd–Ga) synthesized via the same SOMC approach used in this work, where dealloying, even if partial, was always observed under CO 2 hydrogenation conditions. ,,,, Note that the absence of bulk dealloying was also observed for the Au–Zn/SiO 2 system (Au:Zn ca. 33:67) .…”

“…25 The behavior observed for Ni−Ga/SiO 2 contrasts what have been observed for other bimetallic catalysts (i.e., Cu−Zn, 31 Cu−Ga, 10,12 Pd−Ga 18 ) synthesized via the same SOMC approach used in this work, where dealloying, even if partial, was always observed under CO 2 hydrogenation conditions. 12,18,31,59,60 Note that the absence of bulk dealloying was also observed for the Au−Zn/SiO 2 system (Au:Zn ca. 33:67).…”

Metadynamics simulations reveal alloying-dealloying processes for bimetallic PdGa nanoparticles under CO2 hydrogenation

“…their chemical potentials. 3,4 This complexity poses a signicant challenge for elucidating the distribution and nature of active sites, even when using advanced in situ/operando spectroscopic techniques and state-of-the-art computational modelling. 5 For instance, state-of-the-art bimetallic NP catalysts for the selective hydrogenation of CO 2 to methanol exemplify the complexity of dynamic alloying processes as a function of chemical potential or reaction conditions (Fig.…”

“…1b). 4,21 To answer these questions, we confront experimental observations (XAS, chemisorption, CO-adsorption IR) on this well-dened SOMC-derived catalyst with simulations to explore the structural space of PdGa NPs around the free energy minimum under various reactive environments. We rst rene the structure of PdGa NPs and study the inuence of the SiO 2 support on their structure, before addressing the morphological changes of PdGa NPs under different reactive gas atmospheres-H 2 , CO, and oxidizing conditions that correspond to CO 2 hydrogenation.…”

“…their chemical potentials. 3,4 This complexity poses a significant challenge for elucidating the distribution and nature of active sites, even when using advanced in situ / operando spectroscopic techniques and state-of-the-art computational modelling. 5…”