Hydrogen dissociation sites on indium-based ZrO2-supported catalysts for hydrogenation of CO2 to methanol
OPEN ACCESS
Loading...
Author / Producer
Date
2022-03
Publication Type
Journal Article
ETH Bibliography
yes
Citations
Altmetric
OPEN ACCESS
Data
Abstract
The formation and nature of surface indium species in zirconia-supported catalysts for the hydrogenation of CO2 to methanol has been investigated by infrared (IR) spectroscopy. We studied the dissociation of hydrogen on In2O3/m-ZrO2, In2O3/t-ZrO2, In2O3/am-ZrO2 and m-ZrO2:In catalysts (m-, t- and am- refers to monoclinic, tetragonal and amorphous, respectively and m-ZrO2:In is a solid solution material), with and without a redox pretreatment. Indium hydride species and hydroxyl groups form at room temperature on the surface of all redox-treated catalysts upon their exposure to hydrogen. The activity and concentration of surface indium sites capable of heterolytic activation of H2 is the highest in In2O3/m-ZrO2(redox). The sites for the dissociation of hydrogen also exist, although in lower concentration, on the surface of calcined In2O3/m-ZrO2 and m-ZrO2:In catalysts (evacuated at 400 °C), i.e. the catalysts featuring the highest activity in the hydrogenation of CO2 to methanol. Noteworthy, the room temperature reaction between CO2 and Insingle bondH species of redox-treated catalysts gave surface formate species, i.e. intermediates of the methanol synthesis pathway, only for In2O3/m-ZrO2(redox) and m-ZrO2:In(redox), highlighting more favourable reactivity of Insingle bondH species and carbonates on the m-ZrO2 support. In situ X-ray absorption spectroscopy (XAS) at the In K-edge demonstrates the transformation of In2O3/m-ZrO2, during reduction in H2 at 400 °C, into highly dispersed In sites with an average oxidation state between In2+ and In0. Subsequent oxidation recovers the In3+ oxidation state (in the in situ XAS experiment) and forms a m-ZrO2:In solid solution. Thus, H2 dissociation in the most active m-ZrO2:In catalyst proceeds on In3+–O–Zr4+ sites dispersed in m-ZrO2, forming In–H and Zr–OH sites.
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
387
Pages / Article No.
38 - 46
Publisher
Elsevier
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Indium hydrides; H2 dissociation; Methanol synthesis; CO2 hydrogenation; Indium oxide; in situ IR
Organisational unit
03865 - Müller, Christoph R. / Müller, Christoph R.
Notes
Funding
ETH-44 16-2 - The direct integration of CO2 conversion into CO2 capture: Development of model bi-functional Cu-MgO-MOx materials through the elucidation of the carbonation mechanism and active sites for CO2 hydrogenation (ETHZ)
SEED-02 17-2 - Operando experiments to provide fundamental and applied insights into metal oxides catalysts for the dehydrogenation of propane to propene (ETHZ)
819573 - Advancing CO2 Capture Materials by Atomic Scale Design: the Quest for Understanding (EC)
SEED-02 17-2 - Operando experiments to provide fundamental and applied insights into metal oxides catalysts for the dehydrogenation of propane to propene (ETHZ)
819573 - Advancing CO2 Capture Materials by Atomic Scale Design: the Quest for Understanding (EC)