Highly Dispersed Ni Catalyst on Metal-Organic Framework-Derived Porous Hydrous Zirconia for CO 2 Methanation.

We report the preparation of porous hydrous zirconia by treatment of zirconium-based metal-organic framework (MOF) UiO-66 with a strong base. Microporosity of the original MOF was partially retained in the resultant porous hydrous zirconia. Ni ^II centers were then adsorbed onto the OH-rich hydrous zirconia and in situ converted to highly dispersed Ni ⁰ for CO ₂ hydrogenation to CH ₄ . The activated catalyst after an induction period showed a turnover frequency of 345 h ^-1 or a space-time yield of 5851 mmol·g _Ni ^-1 ·h ^-1 with a CH ₄ selectivity of over 99%. The catalyst was tested for 100 h on stream, showing only a 4% decrease in activity, and was found to convert atmospheric CO ₂ to CH ₄ via CO ₂ collection through Na ₂ CO ₃ /NaHCO ₃ cycling. Thermal decomposition of NaHCO ₃ released CO ₂ for hydrogenation to CH ₄ , and the resultant Na ₂ CO ₃ absorbed CO ₂ from air to form NaHCO ₃ . This work highlights the opportunity in using MOFs as precursors to prepare highly porous metal oxide/hydroxide supports for solid-gas phase catalysis.