The solar-driven CO2 utilization is free from the uncertainty of sunlight supply
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(A) THE PROCESS OF NATURAL PHOTOSYNTHESIS. (B) THE PROCESS OF ARTIFICIAL PHOTOSYNTHESIS BY DECOUPLING LIGHT REACTION AND DARK REACTION IN THIS WORK.
view moreCREDIT: ©SCIENCE CHINA PRESS
Converting CO2 into CO, CH4, CH3OH, and other compounds through artificial photocatalysis in all weather conditions is a sustainable approach aimed at concurrently mitigating the energy crisis and realizing net CO2 emission. Photogenerated electrons have a lifespan ranging from sub-picoseconds to a few seconds, resulting in the prompt cessation of the photocatalytic reaction upon the termination of illumination. The inconsistency in the availability of solar energy, influenced by factors like daylight duration and weather conditions, creates a significant barrier for the widespread adoption of solar-driven CO2 conversion.
In a new research article titled “Sustainable all-weather CO2 utilization by mimicking natural photosynthesis in a single material” published in National Science Review, a joint team from the Institute of Earth Environment, Chinese Academy of Sciences, University of Science and Technology of China, Institute of Atmospheric Physics, Chinese Academy of Sciences, and Shaanxi Normal University presented a novel concept to decouple light and dark reaction processes by mimicking natural photosynthesis, showcasing the feasibility of achieving sustainable CO2 conversion even in the absence of light.
They prepared a Pt-loaded hexagonal-WO3 as the model catalyst, for the purpose of storing photogenerated electrons and hydrogen atoms under light irradiation in the dark. The unique characteristics of the WO3 carrier—its ability to alternate between valence states (W6+/W5+) and its hexagonal tunnel structures—combined with Pt's proficiency in water splitting and transferring hydrogen atoms onto the h-WO3 surface and tunnel structures, are the key to achieve the decoupling of light and dark reactions for CO2 conversion. When exposed to simulated sunlight for 10 minutes, the catalyst was able to convert CO2 to CH4 in the dark for 10 days, indicating the possibility of a single material promoting CO2 conversion in all-weather conditions. In pursuit of practical applications, the team designed outdoor experimental equipment and conducted continuous 15-day experiments using natural light. Results revealed that the CO2 reduction process remained effective at night and on rainy days, indicating the proposed concept enables round-the-clock and all-weather CO2 conversion. By separating the light and dark reactions, solar-driven CO2 utilization becomes independent of uncertainties related to sunlight availability.
(A) SCHEMATIC DIAGRAM OF OUTDOOR EXPERIMENTAL EQUIPMENT. (B) SOLAR LIGHT INTENSITY. (C) PRODUCTION OF CH4 IN 16 CONSECUTIVE DAYS WITH 12-H DAYTIME AND 12-H NIGHT-TIME. DAYTIME REPRESENTS 7: 00 TO 19: 00, AND NIGHT-TIME REPRESENTS 19: 00 TO 7: 00 OF THE NEXT DAY. (D) CUMULATIVE YIELD OF CH4.
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©Science China Press
See the article:
Sustainable all-weather CO2 utilization by mimicking natural photosynthesis in a single material
Natl Sci Rev 2023; doi: 10.1093/nsr/nwad275
https://doi.org/10.1093/nsr/nwad275
JOURNAL
National Science Review
Selective conversion of CO2 into dimethyl ether over hydrophobic and gallium-modified copper catalysts
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THE PROXIMITY OF CU AND GA SPECIES OVER CU/GA-SIO2-20ME CATALYST COULD SIMULTANEOUSLY REALIZE TANDEM REACTIONS OF HYDROGENATION OF CO2 TO METHANOL AND DEHYDRATION OF METHANOL TO DME, WHERE FURTHER TRANSPORTATION AND RE-ADSORPTION OF METHANOL INTERMEDIA TO THE HYDROPHOBIC CATALYST WAS AVOIDED. MOREOVER, THE METHYL GROUPS EFFICIENTLY REMOVED THE WATER GENERATED IN THESE TWO REACTIONS, SHIFTING THE REACTION EQUILIBRIUM FORWARD. IN THIS CASE, CO2 CONVERSION AND DME SELECTIVITY WERE BOTH PROMOTED OVER CU/GA-SIO2-20ME CATALYST.
view moreCREDIT: CHINESE JOURNAL OF CATALYSIS
The selective conversion of CO2 and H2 into valuable chemicals and fuels is a promising route for carbon recycling. Multiple routes have been developed for the CO2 hydrogenation to methanol, higher alcohols, dimethyl ether (DME), aromatics, hydrocarbon, and olefins. Among these products, DME is attractive because it is nontoxic and noncorrosive and has been used as a platform chemical in industry, a carrier for hydrogen, and an additive for fuels.
A series of catalysts has been synthesized for the direct hydrogenation of CO2-to-DME via cascade catalysis involving methanol synthesis and methanol condensation to DME over a supported copper catalyst. However, high DME selectivity was only achieved at low conversion of CO2, resulting in poor one-pass productivity. When the CO2 conversion increased, abundant by-products of CO, methanol, and hydrocarbons were produced. A recent trend is CO2 to DME conversion over bifunctional catalysts, such as acid oxide-supported copper nanoparticles, but their performance is still unsatisfactory. In addition, the copper nanoparticles were sintered during catalysis, resulting in poor durability.
Recently, a research team led by Prof. Feng-Shou Xiao and Prof. Liang Wang from Zhejiang University, China, overcomes these limitations by developing a highly active, selective, and durable copper nanoparticle catalyst for converting CO2-to-DME. This was achieved by loading Cu nanoparticles onto hydrophobic and Ga-modified silica supports. The Ga-modified silica provided moderate acidity for methanol dehydration to DME, which hindered deep dehydration to hydrocarbons. Importantly, the hydrophobic catalyst surface efficiently hinders the sintering of the Cu nanoparticles, which is usually triggered by water and methanol. Consequently, under the following reaction conditions (6000 mL gcat–1·h–1, 3 MPa, 240 °C), the CO2 conversion of 9.7%, DME and methanol selectivities of 59.3% and 28.4%, and CO selectivity of only 11.3% were obtained. In a continuous evaluation for 100 h, the performance was well maintained without any deactivation trend, outperforming the general supported Cu catalysts. For more detailed information, please refer to their publication in the Chinese Journal of Catalysis (https://doi.org/10.1016/S1872-2067(23)64535-8).
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About the Journal
Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 16.5. The Editors-in-Chief are Profs. Can Li and Tao Zhang.
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JOURNAL
Chinese Journal of Catalysis
ARTICLE TITLE
Selective hydrogenation of CO2 into dimethyl ether over hydrophobic and gallium-modified copper catalysts
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