Multiple Cuprous Centers Supported on a Titanium-Based Metal-Organic Framework Catalyze CO2 Hydrogenation to Ethylene

Hydrogenation of carbon dioxide (CO2) to ethylene (C2H4) can be achieved in two routes via tandem reactions: (1) CO2 hydrogenation to methanol (CH3OH) followed by methanol-to-olefin conversion and (2) reverse water-gas shift reaction followed by Fischer-Tropsch synthesis. Here we present another tandem route for CO2-to-C2H4 conversion via (3) CO2 hydrogenation to ethanol (C2H5OH) followed by C2H5OH dehydration. Multiple cuprous (Cu-I) centers were loaded onto the Ti-8(mu(2)-O)(8)(mu(2)-OH)(4) secondary building units of a Ti-based metal-organic framework (MOF), MIL-125-NH2, via deprotonation and ion exchange of the mu(2)-OH groups. These multiple Cu-I centers catalyzed CO2 hydrogenation to C2H5OH, while the Ti-2-mu(2)-O-M+ (M+ = H+, Li+) sites converted C2H5OH to C2H4. The MOF achieved CO2-to-C2H4 generation rates of up to 2598 mu mol g(Cat)(-1) h(-1) in supercritical CO2 (CO2 30 MPa, H-2 5 MPa) at 85 degrees C and 514 mu mol g(Cat)(-1) h(-1) in the gas phase at 5 MPa (H-2:CO2 = 3) and 100 degrees C, respectively. This work opens another path to selectively producing C2H4 via the hydrogenation of CO2.

Automated summary

A new tandem route for the conversion of CO2 to C2H4 via CO2 hydrogenation to ethanol followed by ethanol dehydration is presented in this study. Multiple Cu(I) centers loaded onto a Ti-based metal-organic framework catalyzed the conversion, achieving high CO2-to-C2H4 generation rates. This work opens up another path for selectively producing C2H4 through the hydrogenation of CO2.