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Oxy-combustion systems result in enriched CO 2 in exhaust gases; however, the utilization of the concentrated CO 2 stream from oxy-combustion is limited by remnant O 2 . CH 4 oxidation using Pd catalysts has been found to have high O 2 -removal efficiency. Here, the effect of excess CO 2 in the feed stream on O 2 removal with CH 4 oxidation is investigated by combining experimental and theoretical approaches. Experimental results reveal complete CH 4 oxidation without any side-products, and a monotonic increase in the rate of CO 2 generation with an increase in CO 2 concentration in the feed stream. Density-functional theory calculations show that high surface coverage of CO 2 on Pd leads to a reduction in the activation energy for the initial dissociation of CH 4 into CH 3 and H, and also the subsequent oxidation reactions. A CO 2 -rich environment in oxy-combustion systems is therefore beneficial for the reduction of oxygen in exhaust gases.
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Methane Carboxylation Using Electrochemically Activated Carbon Dioxide
Abstract Direct synthesis of CH3COOH from CH4and CO2is an appealing approach for the utilization of two potent greenhouse gases that are notoriously difficult to activate. In thisCommunication, we report an integrated route to enable this reaction. Recognizing the thermodynamic stability of CO2, our strategy sought to first activate CO2to produce CO (through electrochemical CO2reduction) and O2(through water oxidation), followed by oxidative CH4carbonylation catalyzed by Rh single atom catalysts supported on zeolite. The net result was CH4carboxylation with 100 % atom economy. CH3COOH was obtained at a high selectivity (>80 %) and good yield (ca. 3.2 mmol g−1catin 3 h). Isotope labelling experiments confirmed that CH3COOH is produced through the coupling of CH4and CO2. This work represents the first successful integration of CO/O2production with oxidative carbonylation reaction. The result is expected to inspire more carboxylation reactions utilizing preactivated CO2that take advantage of both products from the reduction and oxidation processes, thus achieving high atom efficiency in the synthesis.
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- PAR ID:
- 10414529
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 62
- Issue:
- 27
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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