Low Pressure CO₂ Hydrogenation to Methanol over Gold Nanoparticles Activated on a CeO_x/TiO₂ Interface

Abstract

Capture and recycling of CO2 into valuable chemicals such as alcohols could help mitigate its emissions into the atmosphere. Due to its inert nature, the activation of CO2 is a critical step in improving the overall reaction kinetics during its chemical conversion. Although pure gold is an inert noble metal and cannot catalyze hydrogenation reactions, it can be activated when deposited as nanoparticles on the appropriate oxide support. In this combined experimental and theoretical study, it is shown that an electronic polarization at the metal-oxide interface of Au nanoparticles anchored and stabilized on a CeO(x)/TiO2 substrate generates active centers for CO2 adsorption and its low pressure hydrogenation, leading to a higher selectivity toward methanol. This study illustrates the importance of localized electronic properties and structure in catalysis for achieving higher alcohol selectivity from CO2 hydrogenation.

Product selectivity in plasmonic photocatalysis for carbon dioxide hydrogenation

“…A high E ads,O partially compensates the energy cost for C–O bond cleavage in the CHO intermediates and increases the selectivity towards CH 4 . Although the reaction on the Au catalysts has been reported to involve additional reaction intermediates225960, the selectivity observed here is consistent with the corresponding E ads,O of Rh (5.22 eV) and Au (3.25 eV)61: the Rh catalyst had a slight preference towards CH 4 production under dark conditions, whereas the Au catalyst exclusively produced CO.…”

Hydrogenation of CO2 to Methanol: Importance of Metal–Oxide and Metal–Carbide Interfaces in the Activation of CO2

“…57 In this aspect, the catalytic activities of Au/CeO x /TiO 2 (110) and Cu/CeO x /TiO 2 (110) are similar, see Figure 10, but the selectivity ratio (rate of methanol synthesis / rate of RWGS) is somewhat better for the gold system. 57 It is remarkable that both catalysts are able to produce methanol under low pressures of 100 mTorr of CO 2 and 700 mTorr of H 2 (T= 573 K). Studies of AP-XPS were carried out under these conditions.…”

“…57 The charge transfer between Au 3 and the TiO 2 (110) substrate was found to be essentially zero. On the other hand, when the Au 3 cluster was in contact with the CeO x /TiO 2 (110) surface, see Figure 12, there was a substantial charge redistribution, with Au atoms becoming negatively charged.…”

“…Studies of AP-XPS were carried out under these conditions. 57 In the C 1s region, the Cu/CeO x /TiO 2 (110) and which is the product of the reaction of H with CO 2 on the Cu-ceria and Au-ceria interfaces.…”

Oxide‐Supported Gold Clusters and Nanoparticles in Catalysis: A Computational Chemistry Perspective

“…Often, oxides heterojunctions display interesting properties in terms of charge transfer, oxidation/reduction or stabilization of defects: in the case of a titania/ceria interface, the most interesting junction's effect concerns the stabilization of Ce 3+ centres, thus further increasing ceria's reducibility . Strongly reduced ceria will, in turns, transfer some charge to supported gold clusters, contributing to their activation . This discussion is developed in a joined experimental and computational paper, where the low‐pressure CO 2 hydrogenation to methanol on gold clusters supported on titania/ceria interfaces is studied.…”