Turning CO2 to CH4 and CO over CeO2 and MCF-17 supported Pt, Ru and Rh nanoclusters – Influence of nanostructure morphology, supporting materials and operating conditions

Ali Shan Malik,András Sápi,Gyula Halasi,Anastasiia Efremova,Henrik Bali,Ákos Szamosvölgyi,Fanni Czirok,Břetislav Šmíd,Zoltán Kónya,Ákos Kukovecz

doi:10.1016/j.fuel.2022.124994

Ali Shan Malik, András Sápi + Show 8 more

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https://doi.org/10.1016/j.fuel.2022.124994

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Abstract

• <2 nm Pt, Ru and Rh NCs were anchored over CeO 2 /MCF17. • Supported metal NCs exhibited excellent catalytic performance for CO 2 reduction. • Ru NCs/CeO 2 exhibited ∼ 99% selectivity to CH 4 . • Effect of two entirely different supports (CeO 2 and MCF 17) was evaluated. Efficient conversion of CO 2 into CH 4 and CO brings an important opportunity to get valuable feedstock for a variety of industrially important reactions as both CH 4 and CO are widely used as starting materials for the synthesis of valuable fuels and chemicals. Herein, we synthesized sub-nanometer (<2nm) Platinum (Pt), Ruthenium (Ru) and Rhodium (Rh) nanoclusters (NCs) via colloidal method; successfully decorated over mesoporous CeO 2 and high surface area (HSA) siliceous meso -cellular foam (MCF 17) and tested for high-pressure CO 2 reduction at lower temperature range (220–340 °C). Pt and Ru NCs exhibited typical reverse water gas shift (RWGS) and methanation catalytic performance respectively with minimal influence of the nature of support however, Rh NCs showed drastic variations in the product selectivity which exhibited strong influence of the support over the product distribution. Furthermore, Ru NCs (with a relatively lower metal loading ∼ 1 wt%) were found to be highly selective to CH 4 (∼99 %) and stable (upto 40 hr time on stream) with either CeO 2 /MCF 17 at 340 °C; also Ru NCs exhibited comparatively the highest CO 2 conversion (∼93 % in case of Ru NCs/CeO 2 ) among the supported metal NCs. HRTEM results showed that metal NCs were homogeneously dispersed with a controlled and uniform particle size (<2nm); no substantial agglomeration of Ru NCs were observed after reaction. Beside the stable dispersion of NCs, Near Ambient Pressure (NAP) in situ XPS of Ru/CeO 2 showed that the dynamic Ce 3+ /Ce 4+ ratio of CeO 2 can attribute to the high activity and selectivity.

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