Research Achievements - Other -

1-07 Dissolution Behavior of Mercury Contained in Gypsum Produced from Coal Fired-Power Plant

UACIQUETE Dorcas Linda Ernesto, KATO Takahiro, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  58 ( 0 ) 14 - 15   2021.10

<p>Elution test was carried out in gypsum samples produced from a coal fired power plant, in order to understand the dissolution behavior of mercury when these materials are exposed to rain water. Experiments were carried out in 3 kinds of gypsums, two formed in liquid-column absorber desulfurization equipment and one from the jet bubbling type desulfurization equipment. For the elution test, the conventional batch method and the semi-batch method (improved method) were applied. The results revealed that the dissolution behavior of mercury varied significantly with the testing method. Furthermore, dissolution of mercury increased with decreasing pH. Quantification of mercury in eluate carried out by AAS show that in the conventional method, the dissolved mercury is then adsorbed, on the other hand, in the improved method, this behavior is negligible and only dissolution is observed.</p>

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2-21 Release Behavior of Harmful Elements During Heat Treatments of CCA-treated Wood

KATO Takahiro, HATAKEYAMA Takeshi, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  58 ( 0 ) 64 - 65   2021.10

<p>Chromated copper arsenate–treated wood produced by injecting a solution containing sub–percent of chromium, copper, and arsenic (hereinafter referred to as CCA–treated wood) is one of the construction wastes. As fundamental research on the development of clean gasification process for biomass, pyrolysis (400–800°C) which is the initial stage of gasification and CO₂ gasification (1000°C, 0–60min) characteristics of CCA–treated wood were investigated. The release behavior of high volatile arsenic during pyrolysis and gasification of CCA–treated wood was followed. When the CCA–treated wood was pyrolyzed, the release of arsenic proceeded with increasing temperature and the release extent was 41% at 800°C. In the case of gasification, the release extent of arsenic increased with gasification time and 90% of the arsenic was released into gas phase within 60min. Furthermore, it was possible to suppress the release of arsenic by 800°C during pyrolysis by mixing organic sludge rich in iron and calcium with CCA–treated wood.</p>

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2-12 Removal of Phosphorus from Spent Denitration Catalyst

KATO Takahiro, SAKUSABE Kosuke, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  57 ( 0 ) 42 - 43   2020.10

<p>Adsorption of phosphorus on a denitration catalyst degrades the activity of the catalyst during long-term operation of coal-fired power plants. In order to remove phosphorus and to regenerate a spent catalyst from a real coal-fired power plant, leaching behavior with water and ammonium citrate solution was investigated and change of the catalytic activity was observed. When the catalyst was treated with ammonia citrate, 67% of phosphorus could be removed, and the activity was recovered by restoration of ammonia adsorption capacity. A part of phosphorus (29%) was removed by leaching with distilled water, whereas negligible change in activity was observed.</p>

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1-6 Removal of sulfur and nit rogen from coal extract s using a n ionic liquid

ONODERA Gai, KATO Takahiro, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  56 ( 0 ) 12 - 13   2019.10

<p>In a series studies on development of an advanced desulfurizatio n and denit r o gen ation process of heavy hydrocarbon resources under mild conditions effect of coal type on removal behavior of sulfur and nitrogen was investigated for coal extracts by using imi dazolium type ionic liquid. Sulfur and nit rogen in the coal extracts were simultaneously removed during extraction by the ionic liquid. Nitrogen removal depends on the coal type and nitrogen in the coal extracts prepared from high rank coal was easily removed.</p>

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1-9 Analysis of mercury forms contained in unburned carbon

SAKUSABE Kosuke, TOYOSHIMA Nanako, KATO Takahiro, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  56 ( 0 ) 18 - 19   2019.10

<p>Mercury form analysis was carried out by using temperature programed desorption and cold vapor atomic absorption spectrometry. Model samples of mercury-adsorbed carbon were prepared using activated carbon and unburned carbon separated from coal fly ash. The mercury of adsorbed by unburned carbon (UC-Hg) and activated carbon (AC-Hg) showed different desorption temperature. The TPD curves of UC-Hg and AC-Hg were changed with concentration of mercury in the liquid during adsorption. Considering both forms of UC-Hg and AC-Hg, the quantitative analysis of various mercury forms in desulfurization gypsum can be achieved.</p>

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Development of Efficient Recovery Process for Precious Metals from E-waste

Sakusabe Kosuke, Kato Takahiro, Okawa Hirokazu, Sugawara Katsuyasu

Journal of the Society of Powder Technology, Japan ( The Society of Powder Technology, Japan )  56 ( 3 ) 130 - 135   2019.03

Domestic Co-author

<p>A separation and recovery process of precious metals from E-waste was developed using chlorination. Release behaviors of metal elements from incinerated ash of spent printed circuit board were followed during the heat treatment under a chlorine gas stream. Capturing behaviors of volatilized chlorides were also followed when the chloride gases were supplied to the bed of carbon particles. Rate analysis was conducted for the release and capturing behavior of precious metals obtained by changing the treatment temperature and residence time. Gold and silver in the ash was completely released when heated for 1 hour at 1000°C. The total amounts of released gold and silver from incinerated ash were successfully recovered by adjusting the thickness of the bed of carbon particles at 800°C. The rate analysis for the release and capturing indicated that gold showed lower activation energies for both release and capturing reactions than those of silver.</p>

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Desorption of Carbon Dioxide from Monoethanolamine Solution Using Ultrasound and Calcium Chloride

FUJIWARA Tatsuo, OKAWA Hirokazu, KATO Takahiro, SUGAWARA Katsuyasu

Journal of MMIJ ( The Mining and Materials Processing Institute of Japan )  135 ( 1 ) 1 - 7   2019.01

Domestic Co-author

<p>This study investigated an effective method to desorb CO₂ from low-concentration (0.2 mol/L) monoethanolamine (MEA) solutions using calcium chloride (CaCl₂) and ultrasound irradiation at 25 ºC. The pH value of the solution had a large influence on the desorption ratio of CO₂ from MEA solution under ultrasound irradiation. CO₂ was successfully desorbed up to pH8.2, and it was impossible to desorb CO₂ at pH over 8.2. It was clarified that CO₂ desorption by ultrasound irradiation is useful for the concentration of MEA solution of up to 2.0 mol/L, because the pH rises above 8.2 when the concentration of MEA solution is increased to above 2.0 mol/L. It also became evident that the addition of small amount of CaCl₂ further increases the amount of CO₂ desorbed during ultrasound irradiation.</p>

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No.1-13 Determination of mercury forms in by-products produced from the coal-fired power plant

SAKUSABE Kosuke, KATO Takahiro, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  55 ( 0 ) 26 - 27   2018

Domestic Co-author

<p>Mercury forms in fly ash and desulfurization gypsum produced from the coal-fired power plant were analyzed. A combination of temperature programmed desorption (TPD) and cold vapor atomic absorption spectrometry (CVAAS) was applied and the optimum operating condition was determined to clarify the forms of mercury. TPD curves of mercury obtained for the ash and gypsum were analyzed qualitatively and quantitatively with comparing to the peak temperature and linear combination of TPD curves of model mercury compounds. The results indicated that mercury in the desulfurization gypsum was mainly composed of HgCl2 and the adsorbed one by unburned carbon.</p>

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No.1-9 Removal of organic sulfur from coal extract

ONODERA Gai, KATO Takahiro, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  55 ( 0 ) 18 - 19   2018

Domestic Co-author

<p>In a series of studies on development of an advanced desulfurization process of heavy hydrocarbon resources under mild conditions without pressurized hydrogen and catalyst, removal behavior of organic sulfur was investigated for a coal extract by using sulfur free imidazolium type ionic liquid. Sulfur removal progressed with increasing number of extraction step and 87% of sulfur removal was achieved after the fifth treatment. The coal extract could be recovered at high yields from the ionic liquid phase by back extraction with 1-methylnaphthalene.</p>

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Behavior of Sulfur in Liquid Phase Oxidation of Coal

KATO Takahiro, NAGAI Yuki, OKAWA Hirokazu, SUGAWARA Katsuyasu

Journal of the Japan Institute of Energy ( The Japan Institute of Energy )  97 ( 4 ) 88 - 96   2018

<p>In order to develop an efficient pre-desulfurization technology for both inorganic and organic sulfurs in coals under the mild condition, oxidative desulfurization using hydrogen peroxide was carried out for five kinds of coals with different rank. The coal samples were agitated in the hydrogen peroxide aqueous solution for 2 h at the room temperature. Pyritic sulfur and sulfate as the inorganic sulfur were removed completely from the solid phase by the treatment. Organic sulfur was simultaneously removed, for example, 84% of organic sulfur was reduced for a low rank coal. The removed sulfur from the solid phase dissolved in the hydrogen peroxide aqueous solution as sulfate. XANES analysis showed that thiophenic sulfurs in the coals changed to sulfoxide and sulfone during the hydrogen peroxide treatment. The removal extent of thiophenic sulfur decreased with the increase of the coal rank and correlated well with the aromaticity of the raw coals.</p>

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No.1-11 Oxidative desulfurization of Hyper-coal using hydrogen peroxide and acetic anhydride

ONODERA Gai, KATO Takahiro, OKAWA Hirokazu, SUGAWARA Katuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  54 ( 0 ) 22 - 23   2017

<p>To develop a mild chemical desulfurization method without residual chemicals in the treated Hyper-coal, desulfurization behavior was investigated by oxidation using hydrogen peroxide and acetic anhydride at room temperature and by pyrolyzing the treated sample under nitrogen stream. XANES analysis showed that the Hyper-coal contained only thiophenic sulfur and that the thiophenic sulfur changed to sulfone during the oxidation treatment. High removal extent of sulfur with high char yield was achieved by pyrolyzing the oxidized sample prepared at room temperature for 24 hour.</p>

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No.1-12 Distribution of Sulfur during Solvent Extraction of Coals

TAMURA Mami, KATO Takahiro, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  54 ( 0 ) 24 - 25   2017

<p>In a series of studies on the development of coal utilization process with pre-desulfurization, three types of coal were extracted by 1-methylnapthalene and sulfur distribution from raw coals to products (Soluble, Residue and Deposit) was clarified. XANES analysis indicated that most of pyritic sulfur was distributed to Residue. Soluble contained no inorganic sulfur. Every Soluble obtained from three types of coal contained organic sulfur, especially thiophenic sulfur only. Thiophenic sulfur content in Soluble decreased linearly with the increase of the steps of extraction using an ionic liquid of imidazolium type.</p>

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No.1-13 Simultaneous recovery and desulfurization of bitumen from oil sand using oxidative desulfurization and ultrasound irradiation

AKAZAWA Nobuyuki, OKAWA Hirokazu, Kamal Wan Mohamad Ikhwan Bin Wan, KATO Takahiro, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  54 ( 0 ) 26 - 27   2017

<p>Desulfurization of bitumen was performed by combination of oxidative desulfurization (ODS) and ultrasound irradiation. Tetrahydrofuran (THF) was employed as solvent to emulsify the bitumen and improve the desulfurization ratio. In the result, the desulfurization ratio reached to 82.7% (ion-exchange water: 52%). We also investigated simultaneous recovery and desulfurization of bitumen from oil sand using ODS and ultrasound. Recovery ratio of bitumen from oil sand was 68.1% and the purity of recovered bitumen was 72.3%.</p>

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No.1-15 Recovery of Rare Metals from Spent Denitrification Catalyst

SAKUSABE Kosuke, KATO Takahiro, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  54 ( 0 ) 30 - 31   2017

<p>Selective recovery process of titanium, vanadium and tungsten has been developed for the spent denitrification catalyst produced from coal fired plant. Volatilization behaviors of the rare metals were followed in a chlorine gas stream with the addition of carbon as a reducing agent. Methanol vapor was supplied to a fixed bed of catalyst at 400 °C and fine carbon was deposited on the surface of catalyst. The volatilization rates of the rare metals ware enhanced drastically with the use of the deposited carbon compared to pyrolytic carbon prepared from phenolphthalein. The rare metals in the catalyst could be recovered selectively at 400 °C without silicon, iron and aluminum when the deposited carbon of 20 wt% was used.</p>

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No.2-15 Arsenic Removal from Denitration Catalyst by Carbon Reduction

KATO Takahiro, SATO Yukiko, OKAWA Hirokazu, SUGAWARA Katsuyasu

Proceedings of Conference on Coal Science ( The Japan Institute of Energy )  54 ( 0 ) 80 - 81   2017

<p>Decreasing of activity of the denitration catalyst caused by arsenic adsorption is one of the big problems against the stable long term operation of the coal power plant. In order to remove arsenic from the catalyst by conversion of As₂O₅ to volatile As₂O₃, methanol was used as the carbon source for the reduction. Effects of treatment temperature, reaction time and partial pressure of methanol on changes in the removal extent of arsenic, the chemical forms of vanadium and the denitration activity were investigated.</p>

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