Highly Dispersed Ni Catalyst on Metal-Organic Framework-Derived Porous Hydrous Zirconia for CO2 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. NiII centers were then adsorbed onto the OH-rich hydrous zirconia and in situ converted to highly dispersed Ni0 for CO2 hydrogenation to CH4. The activated catalyst after an induction period showed a turnover frequency of 345 h-1 or a space-time yield of 5851 mmol·gNi-1·h-1 with a CH4 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 CO2 to CH4 via CO2 collection through Na2CO3/NaHCO3 cycling. Thermal decomposition of NaHCO3 released CO2 for hydrogenation to CH4, and the resultant Na2CO3 absorbed CO2 from air to form NaHCO3. This work highlights the opportunity in using MOFs as precursors to prepare highly porous metal oxide/hydroxide supports for solid-gas phase catalysis.