掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Catalysis  

Cyclic and repeatable CO<inf>2</inf>/H<inf>2</inf> formation under periodic CO ↔ H<inf>2</inf>O feeds, that is unsteady-state water–gas shift reaction (uss-WGS), was found to be catalyzed by a gold nanoparticles-loaded CeO<inf>2</inf> (Au/CeO<inf>2</inf>) catalyst. Kinetics of the CO-reduction of Ce⁴⁺ to Ce³⁺ and Ce³⁺ reoxidation by H<inf>2</inf>O in combination with transient CO<inf>2</inf>/H<inf>2</inf> formation over Au/CeO<inf>2</inf> were studied by operando ultraviolet–visible (UV–vis) and infrared (IR) spectroscopies at 175 °C. The Ce⁴⁺–OH species were reduced by CO to give Ce³⁺-□-Ce³⁺ (□: oxygen vacancy) and gas phase products (H<inf>2</inf>, CO<inf>2</inf>). The Ce³⁺-□-Ce³⁺ species were oxidized by H<inf>2</inf>O to give H<inf>2</inf> and Ce⁴⁺–OH species. The reduction and reoxidation rates of Ce⁴⁺/Ce³⁺ redox couple were close to the rates of transient CO<inf>2</inf>/H<inf>2</inf> formation. The X-ray absorption spectroscopy results showed that the oxidation states of Au remained unchanged during the redox reactions. These results indicate that the uss-WGS is primary driven by the Ce⁴⁺/Ce³⁺ redox couple. Combined with the observation of adsorbed carboxylate intermediates as a precursor of H<inf>2</inf> and CO<inf>2</inf>, associative redox mechanism is proposed as the main pathway for the unsteady-state WGS reaction on Au/CeO<inf>2</inf> at 175 °C.

DOI： 10.1016/j.jcat.2024.115500

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Hindawi Limited  

Direct air capturing (DAC) is an energy demanding process for CO2-removal from air. Ongoing research focuses on the potential of indoor air as DAC-feed to profit from currently unused energetic synergies between DAC and the built environment. In this work, we investigated the performance of three different readily available, solid DAC-adsorbers under typical indoor environmental conditions of 16-25°C, 25-60% relative humidity (RH), and CO2-concentrations of less than 800 ppm above atmospheric concentrations. The measured mass-specific CO2-adsorption capacities of K2CO3-impregnated activated carbon, polyethylenimine-snow (PEI-snow), and polyethylenimine (PEI) on silica amount to 6.5±0.3 mg g−1, 52.9±4.9 mg g−1, and 56.9±4.2 mg g−1, respectively. Among the three investigated adsorber materials, PEI on silica is the most promising candidate for DAC-applications as its synthesis is rather simple, the CO2-desorption is feasible at moderate conditions of about 80°C at 100 mbar, and the competing co-adsorption of water does not strongly affect the CO2-adsorption under the investigated experimental conditions.

DOI： 10.1155/2023/8821044

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その他リンク： http://downloads.hindawi.com/journals/ina/2023/8821044.xml

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

DOI： 10.1021/acs.iecr.2c03558

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掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

DOI： 10.1021/acsomega.2c03385

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掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI AG  

Lowering the regeneration temperature for solid CO2-capture materials is one of the critical tasks for economizing CO2-capturing processes. Based on reported pKa values and nucleophilicity, we compared two different polyethylenimines (PEIs): branched PEI (BPEI) and linear PEI (LPEI). LPEI outperformed BPEI in terms of adsorption and desorption properties. Because LPEI is a solid below 73–75 °C, even a high loading amount of LPEI can effectively adsorb CO2 without diffusive barriers. Temperature-programmed desorption (TPD) demonstrated that the desorption peak top dropped to 50.8 °C for LPEI, compared to 78.0 °C for BPEI. We also revisited the classical adsorption model of CO2 on secondary amines by using in situ modulation excitation IR spectroscopy, and proposed a new adsorption configuration, R1(R2)-NCOOH. Even though LPEI is more expensive than BPEI, considering the long-term operation of a CO2-capturing system, the low regeneration temperature makes LPEI attractive for industrial applications.

DOI： 10.3390/en15031075

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Advances  

Perovskite oxides with a low cost and high catalytic activity are considered as suitable candidates for the oxygen evolution reaction (OER)/oxygen reduction reaction (ORR), but most of them favour only either the ORR or the OER. Besides, their underlying catalytic mechanisms are subject of an ongoing debate. Herein, La0.8Sr0.2CoO3-δ (LSC) was selected as a base perovskite oxide for doping different elements into its B-site to fabricate four different La0.8Sr0.2Co0.8M0.2O3-δ (LSCM; M = Ni, Fe, Mn, and Cu) perovskite oxides. Among the catalysts tested with and without multi-walled carbon nanotubes (MWNTs), La0.8Sr0.2Co0.8Fe0.2O3-δ (LSCF) outperformed any other catalysts in terms of both OER and ORR activity. The OER/ORR activity enhancement with LSCF is also discussed based on spectroscopic and microscopic analyses and lattice oxygen transportation.

DOI： 10.1039/d1ma00632k

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記述言語：日本語   会議種別：ポスター発表  

開催地：大阪大学   国名：日本国  

記述言語：日本語   会議種別：ポスター発表  

開催地：大阪大学   国名：日本国  

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：大阪大学   国名：日本国  

記述言語：英語   会議種別：ポスター発表  

開催地：九州大学   国名：日本国  

記述言語：英語   会議種別：ポスター発表  

開催地：九州大学   国名：日本国  

記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：九州大学   国名：日本国  

記述言語：英語   会議種別：口頭発表（一般）  

開催地：東京大学　物性研究所   国名：日本国  

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国