Controlling sintering and carbon deposition with post-coated MgO confined group VIII metal-based catalysts towards durable high-temperature steam reforming

Metal-sintering and carbon-deposition are two bottlenecks in hydrocarbon (e.g., n-dodecane) steam reforming for hydrogen production. Effective inhibition of carbon-deposition by MgO-pre-coating support was intensively confirmed. Unfortunately, we found that weak interaction between Rh-NPs and MgO-pre-coating-CZO induced serious metal-sintering (4→47 nm). To materialize bifunctional suppression, MgO-post-coating confined metal-NPs strategy is proposed. Under the conditions of 700 °C, WHSV = 10 h−1, and S/C = 3 for 50 h, negligible metal-sintering (4→7 nm) and carbon-deposition (0.7 mg C/g cat.) occurred for 5%MgO-1%Rh-Ce0.75Zr0.25O2, whereas Rh-NPs grew to 36 nm and carbon-deposition was 25.6 mg C/g cat. for 1%Rh-Ce0.75Zr0.25O2. Owing to enhanced metal-support-interaction, formed MgO/Rh/CZO interfaces, and increased proportion of Rh0, 5%MgO-1%Rh-Ce0.75Zr0.25O2 showed superior performance. DFT-based calculation results unveiled that MgO-post-coating increased the desorption energies of Rh cluster (0.21→3.29 eV) and individual atoms (3.89→4.35 eV). This study provides an efficient route for realizing sintering resistances of supported metal catalysts in high-temperature hydrothermal atmosphere.