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Selectivity Control in the Direct CO Esterification over Pd@UiO-66: The Pd Location Matters
Shuaishuai Hu1, Chenfan Xie1, Yu-Ping Xu2,3
1Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China.
Angewandte Chemie (International Ed. in English)
|September 1, 2023
Summary
This study introduces a novel method for controlling palladium nanoparticle selectivity in carbon monoxide esterification. By embedding palladium within metal-organic frameworks, researchers achieved high selectivity for dimethyl carbonate production.
Area of Science:
- Materials Science
- Catalysis
- Nanotechnology
Background:
- Controlling selectivity in palladium nanoparticle (Pd NP) catalysis for direct carbon monoxide (CO) esterification is a significant challenge.
- Existing methods often yield mixtures of dimethyl oxalate (DMO) or dimethyl carbonate (DMC).
Purpose of the Study:
- To develop a strategy for achieving high selectivity towards dimethyl carbonate (DMC) in the direct CO esterification reaction using palladium nanoparticles.
- To investigate the effect of palladium nanoparticle location within metal-organic frameworks (MOFs) on catalytic selectivity.
Main Methods:
- Incorporation of palladium nanoparticles (Pd NPs) into isoreticular metal-organic frameworks (MOFs), specifically UiO-66-X (X=-H, -NO2, -NH2), to create Pd@UiO-66-X.
- Comparison of catalytic performance with conventionally supported Pd NPs on MOFs (Pd/UiO-66).
- Utilizing experimental data and Density Functional Theory (DFT) calculations to understand structure-activity relationships.
Main Results:
- Pd@UiO-66-X catalysts demonstrated unexpectedly high selectivity (up to 99%) towards dimethyl carbonate (DMC).
- In contrast, Pd/UiO-66 catalysts showed high selectivity (89%) towards dimethyl oxalate (DMO), consistent with previous findings.
- DFT calculations and experimental results indicated that the distinct microenvironments and interfacial areas between Zr-oxo clusters and Pd NPs in Pd@UiO-66 and Pd/UiO-66 dictate the observed selectivity differences.
Conclusions:
- The location of palladium nanoparticles within or on the surface of MOFs significantly influences their selectivity in direct CO esterification.
- This work presents an unprecedented approach for DMC production using Pd NPs, a transformation previously limited to Pd(II) catalysts.
- The findings open new avenues for designing highly selective heterogeneous catalysts by controlling metal nanoparticle integration within MOF structures.
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