Abstract
MOFs derived supported catalysts showing strong metal-support interactions along with stable and high catalytic activity towards methane dry reforming.
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•One-potsupported Nicatalysts with SMSI are designed by tuning the pyrolysis of MOFs.•Pyrolysis impacts the microstructure, composition, and interface of the derived catalysts.•Coalesced MOFs derived catalyst show high and stable activity for methane dry reforming.•Operando studies revealed the lattice oxygen mobility and carbon pathways under DRM conditions.•Minimal coking and sintering under elevated DRM conditions evidence the robustness of the catalysts.
Dry reforming of methane (DRM) is an inimitable approach for eliminating both greenhouse gases, methane and CO2, while producing synthesis gas which further can be converted to added-value fuels. However, the industrialization of DRM has been limited due to sintering and coking to the catalysts under the harsh reaction conditions. Here, we propose a new methodology for producing tunable supported nickel-based catalysts for DRM using metal organic frameworks (MOFs) as precursors of the catalyst components. In particular, Ni- and La-MOFs were coalesced using sonication and then calcined at different temperatures to produce catalysts with tailored Ni metal size (5–20 nm) and tuned strong metal-support interactions (SMSI). Here, the synthesis of nickel and nickel oxide nanoparticles embedded on lanthanum-based supports by controlled calcination of the MOF structures is demonstrated; the Ni supported catalysts were then used for DRM reaction. Among the developed catalysts, the catalyst produced following calcination at 500 °C (Ni-La-500) has shown stable and high CH4 conversion rates under DRM conditions at 800 °C with negligible carbon formation at elevated gas hourly space velocities. Further, the catalytic performance of Ni-La-500 catalyst (sonicated) was compared to the physically mixed MOFs derived catalyst (Ni-La-500-PM), conventional wetness impregnated catalyst (Ni-La-500 WI), Ni-MOF derived unsupported catalyst (Ni-500), and lower Ni concentration catalyst (sonicated, 10Ni-La-500). The observed CH4 conversion rates at 50,000 mL·gcat–1·h−1 GHSV are 81.8, 67.9, 85.4, 34.7, and 57.9 % for Ni-La-500, Ni-La-500 PM, Ni-La-500 WI, Ni-500, and 10Ni-La-500 catalysts, respectively after 24 h of DRM reaction. With isotopic studies, it was found that the 18O exchange rate was higher in case of Ni-La-500-PM catalyst (8.1 mmol·g−1) as compared to Ni-La-500 catalyst (5.5 mmol·g−1). Prior interaction between MOFs, calcination temperatures, reaction conditions, and the carbon pathways during catalytic activity dictates the conversion rates and selectivity of the products. Overall, with the herein proposed approach of MOF-derived supported catalysts exceptional conversion rates and stability during the DRM reaction with nominal coking and sintering were demonstrated, solving the two major challenges faced by conventional and unsupported catalysts.