研究者詳細 - 大川　浩一

With the aim of investigating the deposition of Au/Pd core-shell nanoparticles (NPs) on cathode materials to decrease charge transfer resistance, Au/Pd core-shell NPs were successfully synthesized and deposited on LiFePO4 coated with carbon (LiFePO4/C) using ultrasound irradiation. Transmission electron microscopy observation confirmed that dispersed Au/Pd NPs with an average particle size of 7.2 nm were deposited on LiFePO4/C. An X-ray diffraction measurement evidenced a peak shifting from 38.2° to 39.1° upon calcination at 400 °C in Ar atmosphere, which can be attributed to the phase transition of the Au/Pd NPs from core-shell to alloy.

DOI

Utilization of tertiary amine solutions and ultrasound irradiation for CO<inf>2</inf> desorption at low temperature in a CCS process

Okawa H.

Japanese Journal of Applied Physics ( Japanese Journal of Applied Physics ) 60 ( SD ) 2021年07月 [査読有り]

研究論文（学術雑誌）国内共著

This study used three tertiary amine solutions as a CO absorbent. Ultrasound can desorb CO from CO (aq) and H CO species at low temperature. Tertiary amine solution with lower pKa created CO adsorption equilibrium at lower pH related to a higher CO desorption amount using 28 kHz ultrasound because the lower pH environment would increase the existence ratio of CO (aq). Triethanolamine (TEA) with lowest pKa (7.85) showed the highest CO desorption ratio of 48% for 30 min irradiation at 25 °C. The CO absorption-desorption capacity of TEA by reuse was evaluated and found to keep the first capacity for three cycles. 2 2 2 2 3 2 2 2 2 2

DOI

Desorption of carbon dioxide from monoethanolamine solution via calcium chloride addition under ultrasound irradiation and evaluation of the characteristics of generated calcium carbonate

Kitamura Y.

Japanese Journal of Applied Physics ( Japanese Journal of Applied Physics ) 60 2021年07月 [査読有り]

研究論文（学術雑誌）国内共著

We report the desorption of carbon dioxide [CO2(g)] from monoethanolamine (MEA) solution via the addition of calcium chloride (CaCl2) into a CO2-Absorbed MEA solution (0.2 M, pH 8.2) under ultrasound treatment (28 kHz, 200 kHz) and stirring (1500 rpm). Ultrasound at 28 kHz had a higher CO2(g) desorption ratio than either ultrasound at 200 kHz or stirring after 1 min [9.2% (28 kHz), 6.2% (stirring), and 5.8% (200 kHz)]. Treatment with ultrasound at 28 kHz resulted in the highest Ca recovery ratio, 89.1%, at 1 min treatment time. The desorption of CO2(g) from the MEA solution using 28 kHz ultrasound started immediately after the initiation of CaCO3 formation. Furthermore, it was found that the average particle size of CaCO3 obtained by ultrasound treatment at 28 kHz and a treatment time of 1 min was 0.91 μm, with a narrow particle size distribution.

DOI

Utilization of tertiary amine solutions and ultrasound irradiation for CO2 desorption at low temperature in a CCS process

Hirokazu Okawa, Hiroyasu Ito, Tatsuo Fujiwara, Yuya Kitamura, Takahiro Kato and Katsuyasu Sugawara

Japanese Journal of Applied Physics 60 SDDD01-1 - SDDD01-4 2021年02月 [査読有り]

研究論文（学術雑誌）国内共著

Preparation of fine copper particles by a wet chemical method

Takahiro Kato, Yuri Takada, Hirokazu Okawa and Katsuyasu Sugawara

Journal of Chemical Engineering of Japan 54 ( 3 ) 103 - 109 2021年01月 [査読有り]

研究論文（学術雑誌）国内共著

Enhancement of bitumen recovery from the oil sand in an alkaline solution using ultrasound irradiation and carbon dioxide

irokazu Okawa, Tomonao Saito, Shohei Yasuda, Youhei Kawamura, Takahiro Kato, Katsuyasu Sugawara and Tayfun Babadagli

Japanese Journal of Applied Physics ( The Japan Society of Applied Physics ) 59 ( SK ) 2020年07月 [査読有り]

研究論文（学術雑誌）国際共著

Herein, we demonstrated the enhancement of bitumen recovery from the oil sand in a concentrated alkaline solution using ultrasound irradiation and carbon dioxide. The alkaline solution allowed the separation of bitumen and sand; however, it was difficult to collect bitumen via aeration. CO2 exhibited a high contact angle for bitumen even at a high pH. Therefore, we attempted to use CO2 for bitumen recovery under ultrasound irradiation, increasing the number of collisions between bitumen and the CO2 bubbles; thus, the bitumen recovery ratio exhibited a high value of approximately 70% even at a low CO2 injection rate of 20 ml min(-1). (C) 2020 The Japan Society of Applied Physics

DOI

Enhancement of desorption amount of carbon dioxide gas from monoethanolamine solution using ultrasound and calcium chloride

Kitamura Y.

Japanese Journal of Applied Physics ( The Japan Society of Applied Physics ) 59 ( SK ) 2020年07月 [査読有り]

研究論文（学術雑誌）国内共著

DOI

Mercury forms contained in desulfurization gypsums

Kosuke Sakusabe, Takahiro Kato, Hirokazu Okawa and Katsuyasu Sugawara

Journal of Chemical Engineering of Japan ( Journal of Chemical Engineering of Japan ) 53 ( 7 ) 359 - 365 2020年07月 [査読有り]

研究論文（学術雑誌）

We analyzed mercury forms in desulfurization gypsum generated at a coal-fired power plant via temperature-programmed desorption (TPD) and cold vapor atomic absorption. The gypsum used as samples was obtained from double contact flow and jet bubbling desulfurization equipment. There were three types of gypsum samples for each type of desulfurization equipment, and six types of samples in all. The total mercury in these samples was 0.36–1.85 ppm. For model samples, we prepared and analyzed carbon with mercury that was adsorbed onto unburned carbon particles separated from fly ash or onto bituminous coal-based activated carbon. The desorption temperature varied depending on the carbon species; as the amount of adsorption increased, the peak width also increased. The TPD behavior of desulfurization gypsum was simulated with a linear combination of TPD curves from model samples. Mercury was found in carbon contained in all desulfurization gypsum analyzed in the present study. Mercury in carbon in the desulfurization gypsum obtained from the double contact flow desulfurization equipment could be simulated with model samples for unburned carbon with adsorbed mercury alone. Further, desulfurization gypsum obtained from jet bubbling desulfurization equipment could be simulated using unburned carbon with adsorbed mercury and activated carbon with adsorbed mercury. With the jet bubbling type of equipment, the abundance ratios of HgO, HgS, and HgSO4·2HgO were higher than those in double contact flow equipment, showing that depending on the type of desulfurization equipment, not only the type of mercury in carbon but also mercury forms in gypsum vary notably.

DOI

Recovery of rare metals from spent denitrification catalysts in coal-fired power plants

Kosuke Sakusabe, Yuuki Mochizuki, Takahiro Kato, Hirokazu Okawa and Katsuyasu Sugawara

Journal of Chemical Engineering of Japan ( Journal of Chemical Engineering of Japan ) 53 ( 7 ) 351 - 358 2020年07月 [査読有り]

研究論文（学術雑誌）国内共著

A process for selectively recovering titanium, vanadium, and tungsten from spent denitrification catalysts generated in coal-fired power plants was developed in this study. Carbon was added as a reducing agent and the chloride volatilization behavior of rare metals under a chlorine gas flow was subsequently tracked. This demonstrated that the chloride volatilization reaction is promoted by the addition of carbon. In addition, if the spent catalyst is heat-treated in methanol vapor to deposit solid carbon on the catalyst surface, the chloride volatilization promotion is particularly high. After carbon was added by this method, heating to 400°C under a chlorine gas flow selectively released rare metals without releasing coexisting elements such as iron and aluminum. In addition, the released rare metals were converted into chlorides upon cooling and were completely recovered in solid or liquid form.

DOI

Removal of arsenite from aqueous solutions using ultrasonic irradiation in the presence of a lead electrode

Miyaki Ohta, Hirokazu Okawa, Takahiro Kato and Katsuyasu Sugawara

Japanese Journal of Applied Physics ( The Japan Society of Applied Physics ) 59 ( SK ) 2020年07月 [査読有り]

研究論文（学術雑誌）国内共著

DOI

Separation of trace magnesium from metallic bismuth by chlorination

Takahiro Kato, Hirokazu Okawa, Katsuyasu Sugawara, Risehiro Nonaka and Masashi Tsuda

Journal of Chemical Engineering of Japan ( Journal of Chemical Engineering of Japan ) 53 ( 7 ) 366 - 374 2020年07月 [査読有り]

研究論文（学術雑誌）国内共著

Open-cell porous silicon is gaining attention for use as a negative electrode to increase the theoretical capacity of lithium-ion batteries. Open-cell porous silicon is prepared by eluting Mg from Mg–Si alloy in molten Bi. To reuse the expensive Bi, separation of trace Mg from Bi is indispensable. Although metallic Mg and Bi form a uniform melting state, MgCl2 floats on the Bi melt. To separate Mg from Mg–Si alloy, effects of different types of chlorinating agents, reaction temperatures, and reaction times on chlorination behavior of Mg and Bi were investigated in this study. When the alloy was heated at 600°C for 21 h, as accumulated reaction time under the decomposition of NH4Cl gas, the Mg content in the sample decreased from the initial 0.9 to 0.1% and 90% of Bi was recovered as melt.

DOI

Adsorption and Desorption Mechanisms of Rare Earth Elements (REEs) by Layered Double Hydroxide(LDH) Modified with Chelating Agents

Shuang Zhang, Naoki Kano, Kenji Mishima, Hirokazu Okawa

Applied science 9 4805-1 - 4805-16 2019年11月 [査読有り]

研究論文（学術雑誌）国際共著

DOI

Mercury Forms in By-Products from Coal-Fired Power Plant

Kosuke Sakusabe, Takahiro Kato, Hirokazu Okawa and Katsuyasu Sugawara

Journal of Chemical Engineering of Japan 52 ( 11 ) 859 - 865 2019年11月 [査読有り]

研究論文（学術雑誌）国内共著

Mercury forms in by-products from coal-fired power plant

Kosuke Sakusabe, Takahiro Kato, Hirokazu Okawa, Katsuyasu Sugawara

Journal of Chemical Engineering of Japan ( 公益社団法人化学工学会 ) 52 ( 11 ) 859 - 865 2019年11月 [査読有り]

研究論文（学術雑誌）国内共著

An analysis of the chemical form of mercury in the by-products produced from a coal-fired power plant was performed by a combining temperature programmed desorption (TPD) method and cold vapor atomic absorption. The TPD curve of the model sample for each mercury compound showed a unique peak temperature, and the chemical form of mercury was identified by comparing the peak temperature with that of the by-product sample. A linear combination of the TPD curve of each model sample was curve-fitted to that of the by-product sample. The ratio of each form of mercury present in the by-products was calculated from the area ratio of the TPD curve of the model sample used in the analysis. The mercury in the fly ash used in this study mainly existed in a form bound to sulfur, and the mercury that adsorbed on carbon was not found despite the very high unburned carbon content. In contrast, the study found that the mercury adsorbed to carbon was the main form of mercury in desulfurization gypsum. These findings suggested that mercury-adsorbed carbon was formed when the mercury that transitioned into the liquid phase in a desulfurization equipment was adsorbed onto the unburned carbon.

DOI CiNii Research

Distribution of Sulfur during Solvent Extraction of Coals and Desulfurization of Extracted Product

Katsuyasu Sugawara, Takahiro Kato, Hirokazu Okawa, Nakorn Worasuwannarak

Journal of Chemical Engineerig of Japan 52 ( 7 ) 610 - 615 2019年07月 [査読有り]

研究論文（学術雑誌）国内共著

Removal of Arsenic from a Denitration Catalyst by Reduction Using Methanol as Carbon Source

Takahiro Kato, Kosuke Sakusabe, Yuki Mochizuki, Hirokazu Okawa, KatsuyasuSugawara

Reaction Chemistry & Engineering 4 1208 - 1215 2019年07月 [査読有り]

研究論文（学術雑誌）国内共著

DOI

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