Enhancing DMC Production from CO<sub>2</sub>: Tuning Oxygen Vacancies and In Situ Water Removal
The direct synthesis of dimethyl carbonate (DMC) from methanol and CO<sub>2</sub> presents an attractive route to turn abundant CO<sub>2</sub> into value-added chemicals. However, insufficient DMC yields arise due to the inert nature of CO<sub>2</sub> and the limi...
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MDPI AG
2024-02-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/17/4/839 |
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| author | Kaiying Wang Shiguang Li Miao Yu Xinhua Liang |
| author_facet | Kaiying Wang Shiguang Li Miao Yu Xinhua Liang |
| author_sort | Kaiying Wang |
| collection | DOAJ |
| description | The direct synthesis of dimethyl carbonate (DMC) from methanol and CO<sub>2</sub> presents an attractive route to turn abundant CO<sub>2</sub> into value-added chemicals. However, insufficient DMC yields arise due to the inert nature of CO<sub>2</sub> and the limitations of reaction equilibrium. Oxygen vacancies are known to facilitate CO<sub>2</sub> activation and improve catalytic performance. In this work, we have demonstrated that tuning oxygen vacancies in catalysts and implementing in situ water removal can enable highly efficient DMC production from CO<sub>2</sub>. Ce<i><sub>x</sub></i>Zr<i><sub>y</sub></i>O<sub>2</sub> nanorods with abundant oxygen vacancies were synthesized via a hydrothermal method. In liquid-phase DMC synthesis, the Ce<sub>10</sub>Zr<sub>1</sub>O<sub>2</sub> nanorods exhibited a 1.7- and 1.4-times higher DMC yield compared to CeO<sub>2</sub> nanoparticles and undoped CeO<sub>2</sub> nanorods, respectively. Zr doping yielded a CeZr solid solution with increased oxygen vacancies, promoting CO<sub>2</sub> adsorption and activation. In addition, adding 2-cyanopyridine as an organic dehydrating agent achieved an outstanding 87% methanol conversion and >99% DMC selectivity by shifting the reaction equilibrium to the desired product. Moreover, mixing CeO<sub>2</sub> nanoparticles with hydrophobic fumed SiO<sub>2</sub> in gas-phase DMC synthesis led to a doubling of DMC yield. This significant increase was attributed to the faster diffusion of water molecules away from the catalyst surface, facilitated by the hydrophobic SiO<sub>2</sub>. This study illustrates an effective dual strategy of enhancing oxygen vacancies and implementing in situ water removal to boost DMC production from CO<sub>2</sub>. The strategy can also be applied to other reactions impacted by water accumulation. |
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| language | English |
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| series | Energies |
| spelling | doaj.art-88423e81bb3148efb2eedde33fe6cb3e2024-02-23T15:15:13ZengMDPI AGEnergies1996-10732024-02-0117483910.3390/en17040839Enhancing DMC Production from CO<sub>2</sub>: Tuning Oxygen Vacancies and In Situ Water RemovalKaiying Wang0Shiguang Li1Miao Yu2Xinhua Liang3Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USAGTI Energy, Des Plaines, IL 60018, USADepartment of Chemical and Biological Engineering and RENEW Institute, University at Buffalo, Buffalo, NY 14260, USADepartment of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USAThe direct synthesis of dimethyl carbonate (DMC) from methanol and CO<sub>2</sub> presents an attractive route to turn abundant CO<sub>2</sub> into value-added chemicals. However, insufficient DMC yields arise due to the inert nature of CO<sub>2</sub> and the limitations of reaction equilibrium. Oxygen vacancies are known to facilitate CO<sub>2</sub> activation and improve catalytic performance. In this work, we have demonstrated that tuning oxygen vacancies in catalysts and implementing in situ water removal can enable highly efficient DMC production from CO<sub>2</sub>. Ce<i><sub>x</sub></i>Zr<i><sub>y</sub></i>O<sub>2</sub> nanorods with abundant oxygen vacancies were synthesized via a hydrothermal method. In liquid-phase DMC synthesis, the Ce<sub>10</sub>Zr<sub>1</sub>O<sub>2</sub> nanorods exhibited a 1.7- and 1.4-times higher DMC yield compared to CeO<sub>2</sub> nanoparticles and undoped CeO<sub>2</sub> nanorods, respectively. Zr doping yielded a CeZr solid solution with increased oxygen vacancies, promoting CO<sub>2</sub> adsorption and activation. In addition, adding 2-cyanopyridine as an organic dehydrating agent achieved an outstanding 87% methanol conversion and >99% DMC selectivity by shifting the reaction equilibrium to the desired product. Moreover, mixing CeO<sub>2</sub> nanoparticles with hydrophobic fumed SiO<sub>2</sub> in gas-phase DMC synthesis led to a doubling of DMC yield. This significant increase was attributed to the faster diffusion of water molecules away from the catalyst surface, facilitated by the hydrophobic SiO<sub>2</sub>. This study illustrates an effective dual strategy of enhancing oxygen vacancies and implementing in situ water removal to boost DMC production from CO<sub>2</sub>. The strategy can also be applied to other reactions impacted by water accumulation.https://www.mdpi.com/1996-1073/17/4/839DMC synthesisCeZr solid solutionCeO<sub>2</sub> nanorodsoxygen vacanciesdehydrating agent |
| spellingShingle | Kaiying Wang Shiguang Li Miao Yu Xinhua Liang Enhancing DMC Production from CO<sub>2</sub>: Tuning Oxygen Vacancies and In Situ Water Removal Energies DMC synthesis CeZr solid solution CeO<sub>2</sub> nanorods oxygen vacancies dehydrating agent |
| title | Enhancing DMC Production from CO<sub>2</sub>: Tuning Oxygen Vacancies and In Situ Water Removal |
| title_full | Enhancing DMC Production from CO<sub>2</sub>: Tuning Oxygen Vacancies and In Situ Water Removal |
| title_fullStr | Enhancing DMC Production from CO<sub>2</sub>: Tuning Oxygen Vacancies and In Situ Water Removal |
| title_full_unstemmed | Enhancing DMC Production from CO<sub>2</sub>: Tuning Oxygen Vacancies and In Situ Water Removal |
| title_short | Enhancing DMC Production from CO<sub>2</sub>: Tuning Oxygen Vacancies and In Situ Water Removal |
| title_sort | enhancing dmc production from co sub 2 sub tuning oxygen vacancies and in situ water removal |
| topic | DMC synthesis CeZr solid solution CeO<sub>2</sub> nanorods oxygen vacancies dehydrating agent |
| url | https://www.mdpi.com/1996-1073/17/4/839 |
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