(765h) Creating Metal-Oxide Interfaces in Metal Organic Framework for Efficient Methanol Synthesis from CO2

Authors: 
Gutiérrez, O., Pacific Northwest National Laboratory
Zhu, Y., Pacific Northwest National Laboratory
Zheng, J., Pacific Northwest National Laboratory
Cui, Y., Pacific Northwest National Laboratory
Koh, K., Pacific Northwest National Laboratory
Kovarik, L., Pacific Northwest National Laboratory
Camaioni, D. M., Pacific Northwest National Laboratory
Fulton, J. L., Pacific Northwest National Laboratory
Lercher, J. A., Pacific Northwest National Laboratory

Figure 1. (A) Schematic view of the approach for
creating interfaces between metal nanoparticles in 3-D frameworks. (B) The Cu
k-edge XAFS and the fitted spectrum suggesting Cu nanoclusters locate in the
pores of MOF with ~30% Cu-O-Zr interfacial sites. (C) The activity in selective
hydrogenation of CO2 to methanol suggesting Cu/UiO66 has superior
performance.

Interfaces
between metals and metal oxides have high activity for activation and
conversion of CO2, whereas they are just accessible on the perimeter
of the metal nanoparticles on traditional supported catalysts. We present here
a strategy for the synthesis of well-defined metal-metal oxide interfaces by
incorporating metal nanoparticles into the pores of metal organic frameworks
(UiO-66 and ZIF-8) (Figure 1A). Pd or Cu nanoparticles bind to the
hydroxyl groups of the secondary building units (SBUs), i.e., Zr6 oxide
or ZnN4 clusters (UiO-66 and ZIF-8, respectively). As a result, the
proportion of metal atoms located at the interfaces with the SBUs is maximized
(Cu in UiO-66, Figure 1B). Our novel systems are highly active for the
selective conversion of CO2 to methanol even compared to commercial
catalysts and highly dispersed metal clusters deposited in zeolites. For
instance, Cu/UiO-66 is more active than the Cu on bulk ZrO2 and
commercial Cu/ZnO/Al2O3 catalyst (Figure 1C). Our
work highlights the advantages of combining the architecture and chemical
features of MOF with small metal entities for CO2 and H2
activation.