Tetrachlorocobaltate-Catalyzed Methane Oxidation to Methyl Trifluoroacetate
In ongoing attempts to efficiently utilize abundant natural gas, there has been steady scientific and industrial interest in using an environmentally benign and inexpensive oxidant (dioxygen O<sub>2</sub>) for the direct catalytic oxidation of methane to oxygenate products under mild con...
Main Authors: | , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
MDPI AG
2022-11-01
|
Series: | Catalysts |
Subjects: | |
Online Access: | https://www.mdpi.com/2073-4344/12/11/1419 |
_version_ | 1797465725989814272 |
---|---|
author | Huyen Tran Dang Seokhyeon Cheong Jiyun Kim Ngoc Tuan Tran Honggon Kim Hyunjoo Lee |
author_facet | Huyen Tran Dang Seokhyeon Cheong Jiyun Kim Ngoc Tuan Tran Honggon Kim Hyunjoo Lee |
author_sort | Huyen Tran Dang |
collection | DOAJ |
description | In ongoing attempts to efficiently utilize abundant natural gas, there has been steady scientific and industrial interest in using an environmentally benign and inexpensive oxidant (dioxygen O<sub>2</sub>) for the direct catalytic oxidation of methane to oxygenate products under mild conditions. Here, we report the homogeneous bis(tetramethylammonium) tetrachlorocobaltate ([Me<sub>4</sub>N]<sub>2</sub>CoCl<sub>4</sub>)-catalyzed methane oxidation to methyl trifluoroacetate (MeTFA) with dioxygen O<sub>2</sub> in trifluoroacetic acid (HTFA) media. [Me<sub>4</sub>N]<sub>2</sub>CoCl<sub>4</sub> had the highest catalytic activity among previously reported homogeneous cobalt-based catalyst systems; the turnover of methane to MeTFA reached 8.26 mol<sub>ester</sub> mol<sub>metal</sub><sup>−1</sup>h<sup>−1</sup> at 180 °C. Results suggest that the ionic form of the catalyst makes the Co species more soluble in the HTFA media; consequently, an active catalyst form, [CoTFA<sub>x</sub>Cl<sub>y</sub>]<sup>2−</sup>, can form very rapidly. Furthermore, chloride anions dissociated from CoCl<sub>4</sub><sup>2−</sup> appear to suppress oxidation of the solvent HTFA, thereby driving the reaction toward methane oxidation. The effects of reaction time, catalyst concentration, O<sub>2</sub> and methane pressure, and reaction temperature on MeTFA production were also investigated. |
first_indexed | 2024-03-09T18:25:38Z |
format | Article |
id | doaj.art-ad21cd4dc4a84ae6b2627c5e5ceb79ca |
institution | Directory Open Access Journal |
issn | 2073-4344 |
language | English |
last_indexed | 2024-03-09T18:25:38Z |
publishDate | 2022-11-01 |
publisher | MDPI AG |
record_format | Article |
series | Catalysts |
spelling | doaj.art-ad21cd4dc4a84ae6b2627c5e5ceb79ca2023-11-24T07:55:47ZengMDPI AGCatalysts2073-43442022-11-011211141910.3390/catal12111419Tetrachlorocobaltate-Catalyzed Methane Oxidation to Methyl TrifluoroacetateHuyen Tran Dang0Seokhyeon Cheong1Jiyun Kim2Ngoc Tuan Tran3Honggon Kim4Hyunjoo Lee5Clean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, KoreaClean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, KoreaDivision of Energy & Environment Technology, KIST School, Korea University of Science and Technology, Seoul 02792, KoreaClean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, KoreaDivision of Energy & Environment Technology, KIST School, Korea University of Science and Technology, Seoul 02792, KoreaClean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, KoreaIn ongoing attempts to efficiently utilize abundant natural gas, there has been steady scientific and industrial interest in using an environmentally benign and inexpensive oxidant (dioxygen O<sub>2</sub>) for the direct catalytic oxidation of methane to oxygenate products under mild conditions. Here, we report the homogeneous bis(tetramethylammonium) tetrachlorocobaltate ([Me<sub>4</sub>N]<sub>2</sub>CoCl<sub>4</sub>)-catalyzed methane oxidation to methyl trifluoroacetate (MeTFA) with dioxygen O<sub>2</sub> in trifluoroacetic acid (HTFA) media. [Me<sub>4</sub>N]<sub>2</sub>CoCl<sub>4</sub> had the highest catalytic activity among previously reported homogeneous cobalt-based catalyst systems; the turnover of methane to MeTFA reached 8.26 mol<sub>ester</sub> mol<sub>metal</sub><sup>−1</sup>h<sup>−1</sup> at 180 °C. Results suggest that the ionic form of the catalyst makes the Co species more soluble in the HTFA media; consequently, an active catalyst form, [CoTFA<sub>x</sub>Cl<sub>y</sub>]<sup>2−</sup>, can form very rapidly. Furthermore, chloride anions dissociated from CoCl<sub>4</sub><sup>2−</sup> appear to suppress oxidation of the solvent HTFA, thereby driving the reaction toward methane oxidation. The effects of reaction time, catalyst concentration, O<sub>2</sub> and methane pressure, and reaction temperature on MeTFA production were also investigated.https://www.mdpi.com/2073-4344/12/11/1419methaneoxidationairmethyl trifluoroacetatecobalt catalyst |
spellingShingle | Huyen Tran Dang Seokhyeon Cheong Jiyun Kim Ngoc Tuan Tran Honggon Kim Hyunjoo Lee Tetrachlorocobaltate-Catalyzed Methane Oxidation to Methyl Trifluoroacetate Catalysts methane oxidation air methyl trifluoroacetate cobalt catalyst |
title | Tetrachlorocobaltate-Catalyzed Methane Oxidation to Methyl Trifluoroacetate |
title_full | Tetrachlorocobaltate-Catalyzed Methane Oxidation to Methyl Trifluoroacetate |
title_fullStr | Tetrachlorocobaltate-Catalyzed Methane Oxidation to Methyl Trifluoroacetate |
title_full_unstemmed | Tetrachlorocobaltate-Catalyzed Methane Oxidation to Methyl Trifluoroacetate |
title_short | Tetrachlorocobaltate-Catalyzed Methane Oxidation to Methyl Trifluoroacetate |
title_sort | tetrachlorocobaltate catalyzed methane oxidation to methyl trifluoroacetate |
topic | methane oxidation air methyl trifluoroacetate cobalt catalyst |
url | https://www.mdpi.com/2073-4344/12/11/1419 |
work_keys_str_mv | AT huyentrandang tetrachlorocobaltatecatalyzedmethaneoxidationtomethyltrifluoroacetate AT seokhyeoncheong tetrachlorocobaltatecatalyzedmethaneoxidationtomethyltrifluoroacetate AT jiyunkim tetrachlorocobaltatecatalyzedmethaneoxidationtomethyltrifluoroacetate AT ngoctuantran tetrachlorocobaltatecatalyzedmethaneoxidationtomethyltrifluoroacetate AT honggonkim tetrachlorocobaltatecatalyzedmethaneoxidationtomethyltrifluoroacetate AT hyunjoolee tetrachlorocobaltatecatalyzedmethaneoxidationtomethyltrifluoroacetate |