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Ni5Ga3 catalysts for CO2 reduction to methanol: Exploring the role of Ga surface oxidation/reduction on catalytic activity

Gallo, Alessandro, Snider, Jonathan L., Sokaras, Dimosthenis, Nordlund, Dennis, Kroll, Thomas, Ogasawara, Hirohito, Kovarik, Libor, Duyar, Melis S. and Jaramillo, Thomas F. (2019) Ni5Ga3 catalysts for CO2 reduction to methanol: Exploring the role of Ga surface oxidation/reduction on catalytic activity Applied Catalysis B: Environmental, 118369.

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Abstract

A δ-Ni5Ga3/SiO2 catalyst, which is highly active and stable for thermal CO2 hydrogenation to methanol, was investigated to understand its surface dynamics during reaction conditions. The catalyst was prepared, tested and characterized using a multitude of techniques, including ex-situ XRD (X-ray Diffraction), TEM (Transmission Electron Microscopy), H2-TPR (Temperature Programmed Reduction), CO chemisorption, along with in-situ ETEM (Environmental Transmission Electron Microscopy), APXPS (Ambient Pressure X-ray Photoelectron Spectroscopy) and HERFD-XAS (High Energy Resolution Fluorescence Detected X-Ray Absorption Spectroscopy). Upon air exposure Ga migrates from the subsurface region to the surface of the nanoparticles forming a Ga-oxide shell surrounding a metallic core. The oxide shell can be reduced completely only at high temperatures (above 600 °C); the temperature of the reducing activation treatment plays a crucial role on the catalytic activity. HERFD-XAS and APXPS measurements show that an amorphous Ga2O3 shell persists during catalysis after low temperature reductions, promoting methanol synthesis.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Chemical and Process Engineering
Authors :
NameEmailORCID
Gallo, Alessandro
Snider, Jonathan L.
Sokaras, Dimosthenis
Nordlund, Dennis
Kroll, Thomas
Ogasawara, Hirohito
Kovarik, Libor
Duyar, Melis S.m.duyar@surrey.ac.uk
Jaramillo, Thomas F.
Date : 4 November 2019
DOI : 10.1016/j.apcatb.2019.118369
Copyright Disclaimer : © 2019 Published by Elsevier B.V.
Uncontrolled Keywords : Ni-Ga; Intermetallic; Methanol synthesis; In-Situ characterization; Ga2O3 CO2utilization
Depositing User : Diane Maxfield
Date Deposited : 29 Nov 2019 15:52
Last Modified : 02 Dec 2019 10:21
URI: http://epubs.surrey.ac.uk/id/eprint/853220

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