CO2 Methanation on Supported Rh Nanoparticles: The combined Effect of Support Oxygen Storage Capacity and Rh Particle Size

Georgia Botzolaki,Maria Goula,Anatoli Rontogianni,Nikolaos Charisiou,Stylianos Papadopoulos,Panagiota Zygouri,Dimitrios Gournis,Michalis Karakassides,Ersi Nikolaraki,Ioannis Yentekakis,Grammatiki Goula,Nikolaos Chalmpes

doi:10.3390/catal10080944

Abstract

CO2 hydrogenation toward methane, a reaction of high environmental and sustainable energy importance, was investigated at 200–600 °C and H2/CO2 = 4/1, over Rh nanoparticles dispersed on supports with different oxygen storage capacity characteristics (γ-Al2O3, alumina-ceria-zirconia, and ceria-zirconia). The effects of the support OSC and Rh particle size on reaction behavior under both integral and differential conditions were investigated, to elucidate the combined role of these crucial catalyst design parameters on methanation efficiency. A volcano-type variation of methanation turnover frequency was found in respect to support OSC; Rh/ACZ, with intermediate OSC, was the optimal catalyst. The structure sensitivity of the reaction was found to be a combined function of support OSC and Rh particle size: For Rh/γ-Al2O3 (lack of OSC) methanation was strongly favored on small particles—the opposite for Rh/CZ (high OSC). The findings are promising for rational design and optimization of CO2 methanation catalysts by tailoring the aforementioned characteristics.

Highlights

IntroductionFossil fuels (coal, oil, and natural gas) remain the dominant source of energy in the industrial, commercial, residential, and transportation sectors
Fossil fuels remain the dominant source of energy in the industrial, commercial, residential, and transportation sectors
We report on the intrinsic and integral CO2 methanation activity and selectivity of different sizes Rh nanoparticles deposited on oxide supports encompassing a wide range of oxygen storage capacity (OSC), namely γ-Al2 O3, alumina–ceria–zirconia (ACZ: 80 wt % Al2 O3 –20 wt % Ce0.5 Zr0.5 O2-δ ), and ceria-zirconia (CZ: Ce0.5 Zr0.5 O2-δ ), in a comparative manner

Summary

Introduction

Fossil fuels (coal, oil, and natural gas) remain the dominant source of energy in the industrial, commercial, residential, and transportation sectors. Besides the fact that fossil fuels are finite, fossil fuel utilization leads to the emission of tremendous quantities of CO2 in the atmosphere: These have risen from ~280 ppm before the industrial revolution to ~410 ppm nowadays. Control of CO2 emissions is a critical and urgent environmental issue [1,2,3,4,5,6,7,8,9]. A possible solution can be provided by energy models with a reduced environmental footprint that can be combined with the so-called cyclic economy strategies [4,9,10,11,12,13,14].

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