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CO2 reduction over Mo2 C-based catalysts

DOI: 10.1021/acscatal.0c05019 DOI Help

Authors: Wijnand Marquart (University of Cape Town; DST-NRF Centre of Excellence in Catalysis c*change) , Shaine Raseale (University of Cape Town) , Gonzalo Prieto (Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas (UPV-CSIC)) , Anna Zimina (Karlsruhe Institute of Technology) , Bidyut Bikash Sarma (Karlsruhe Institute of Technology) , Jan-Dierk Grunwaldt (Karlsruhe Institute of Technology) , Michael Claeys (University of Cape Town) , Nico Fischer (University of Cape Town)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Catalysis

State: Published (Approved)
Published: January 2021

Abstract: Four Mo-based catalysts were prepared via three different synthesis techniques supported on SiO2 and/or SBA-15. By means of complementary in situ characterization techniques, the carburization process and the final characteristics of these catalysts were investigated. Additionally, the four catalysts were evaluated for the activation of CO2 in the absence and presence of H2 (reverse water–gas shift, RWGS). The results suggest that CO2 reacts via a dissociation on the carbide surface, forming adsorbed oxygen surface species. Severe oxidation of the carbide into its oxidic phases (MoO2 or MoO3) only occurs at temperatures above 850 K in the presence of CO2. O2 dissociates on the carbide surface when introduced at low concentrations (1 vol %) at room temperature, but when exposed to higher concentrations, a strong exothermic bulk re-oxidation reaction occurs, forming MoO2. All four catalysts show high RWGS activity in terms of CO2 conversions with a minimum CO selectivity of 98% without any signs of bulk catalyst oxidation. Although minimal, the observed deactivation is suggested to be primarily due to phase changes between Mo2C allotropes (β-phase, oxycarbide, and η-phase) and/or sintering of the active phase.

Journal Keywords: carbon dioxide; hydrogen; reverse water−gas shift; molybdenum carbide; in situ XRD; in situ Raman spectroscopy; in situ XAS

Diamond Keywords: Carbon Capture and Storage (CCS)

Subject Areas: Chemistry, Environment

Instruments: B18-Core EXAFS

Added On: 25/01/2021 10:00

Discipline Tags:

Earth Sciences & Environment Climate Change Physical Chemistry Catalysis Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS)