Nature of the Pt-Cobalt-Oxide surface interaction and its role in the CO2 Methanation

Anastasiia Efremova,Imre Szenti,János Kiss,Ákos Szamosvölgyi,András Sápi,Kornélia Baán,Luca Olivi,Gábor Varga,Zsolt Fogarassy,Béla Pécz,Ákos Kukovecz,Zoltán Kónya

doi:10.1016/j.apsusc.2021.151326

Abstract

Based on our previous investigations, it turned out that the Co3O4 material is a promising catalyst in the ambient pressure CO2 methanation. This work aims at understanding the Pt-Cobalt-Oxide surface interaction and its effect on the catalytic performance. The incorporation of Pt nanoparticles into the mesoporous Co3O4 (Pt/m-Co3O4) and commercial Co3O4 (Pt/c-Co3O4) improves the catalytic activity of both catalysts by a factor of ∼ 1.4 and ∼ 1.9 respectively at 673 K. The same tendency towards the increased basicity was also observed. Morphology-induced surface basicity was previously shown to play a key role in determining the catalytic activity of free-standing supports. From HR-TEM (-EDX), EXAFS, CO2-TPD, and CO chemisorption measurements it was established that during the pre-treatment, Co-Pt alloy particles partially covered by the CoxOy layer are formed. It has been postulated that this structure transformation generates new basic centres, the amount of which per unit surface area is significantly larger for Pt/c-Co3O4 and this in turn is responsible for the higher enhancement effect of the Pt/c-Co3O4 catalyst in the CO2 methanation. This study emphasizes the importance of the surface structure exploration for the dynamic catalytic systems in order to reach maximum activity and selectivity in the CO2 methanation.

Highlights

The rapid development of technical and technological applications over the past few centuries has been accompanied by the utilization of carbon fuels, injudicious deforestation, and the decrease of green spaces
Combining High Resolution Transmission Electron Microscopy (HR-TEM) (-EDX), edge X-ray absorption fine structure (EXAFS), X-Ray Photoelectron Spectroscopy (XPS), CO2-temperature-programmed desorption (TPD), Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) data and the results of the CO chemisorption analysis, we propose the following sketch (Fig. 8.), illustrating the structure and mechanisms operating for the catalysts during CO2 methanation reaction
The incorporation of 1% 5 nm Pt nanoparticles onto m-Co3O4 and cCo3O4 allowed higher CO2 consumption rates, slightly diminishing their CH4 selectivity in the CO2 hydrogenation reaction

Summary

Introduction

The rapid development of technical and technological applications over the past few centuries has been accompanied by the utilization of carbon fuels, injudicious deforestation, and the decrease of green spaces. This has brought about an increase in the amount of carbon dioxide in the Earth’s biosphere, which is associated with the adverse effects on climate change [1,2]. Heterogeneous catalytic hydrogenation opens a perspective way to involve cheap, safe, and renewable CO2 source into a chemical interaction and allows the production of valuable synthetic fuel components, such as methane. The Cobalt oxide containing catalysts, including their Pt metal-modified structures are in the focus of heterogeneous catalytic and electrocatalytic appli cations, their morphology and surface chemistry character ization are the subject of recent investigations [16,17,18]

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Conclusion