Catalytic Hydrogenation of CO2 to Methanol over Cu/MgO Catalysts in a Semi-Continuous Reactor

Susanne Lux,Moritz Pallua,Matthäus Siebenhofer,Sascha Kleiber

doi:10.3390/en14144319

Abstract

Methanol synthesis from carbon dioxide (CO2) may contribute to carbon capture and utilization, energy fluctuation control and the availability of CO2-neutral fuels. However, methanol synthesis is challenging due to the stringent thermodynamics. Several catalysts mainly based on the carrier material Al2O3 have been investigated. Few results on MgO as carrier material have been published. The focus of this study is the carrier material MgO. The caustic properties of MgO depend on the caustification/sintering temperature. This paper presents the first results of the activity of a Cu/MgO catalyst for the low calcining temperature of 823 K. For the chosen calcining conditions, MgO is highly active with respect to its CO2 adsorption capacity. The Cu/MgO catalyst showed good catalytic activity in CO2 hydrogenation with a high selectivity for methanol. In repeated cycles of reactant consumption and product condensation followed by reactant re-dosing, an overall relative conversion of CO2 of 76% and an overall selectivity for methanol of 59% was obtained. The maximum selectivity for methanol in a single cycle was 88%.

Highlights

The steadily increasing carbon dioxide (CO2 ) concentration in the atmosphere demands reduction of CO2 emissions and necessitate CO2 mitigation strategies [1]
The topic has been investigated in an ongoing project to collect data about the interaction of sintering temperature dependent MgO reactivity and the catalytic activity of Cu/MgO catalysts
The results indicate that the activity of the catalyst, as prepared, still becomes better after 48 h of operation

Summary

Introduction

The steadily increasing carbon dioxide (CO2 ) concentration in the atmosphere demands reduction of CO2 emissions and necessitate CO2 mitigation strategies [1]. Due to its higher performance, lower emissions and lower flammability compared to gasoline, methanol is classified as an alternative to conventional fossil-based fuels [2,3,4,5,6,7,8,9,10]. Methanol can be used as an energy carrier to store excess energy from wind and solar power plants at peak production times. Excess electric energy is converted into chemical ’hydrogen-fixed energy’ by electrolysis of water, and consecutive synthesis of methanol via CO2 hydrogenation improves the energy density of H2 -based energy carriers by one order of magnitude [11]. Methanol releases H2 by steam reforming, it is, highly feasible for fuel cell powering [12]. Gas turbines have been shown to successfully run on methanol, which can be used to provide electricity in remote regions [13]

Methods

Results

Conclusion