• Title/Summary/Keyword: 2-step thermochemical water splitting

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2-Step Thermochemical Water Splitting on a Active Material Washcoated Monolith Using a Solar Simulator as Heat Source (인공태양을 이용한 모노리스 적용 반응기에서 2단계 열화학적 물분해 연구)

  • Kang, Kyoung-Soo;Kim, Chang-Hee;Park, Chu-Sik
    • Transactions of the Korean hydrogen and new energy society
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    • v.18 no.2
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    • pp.109-115
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    • 2007
  • Solar energy conversion to hydrogen was carried out via a two-step thermochemical water splitting using metal oxide redox pair. To simulate the solar radiation, a 7 kW short arc Xe-lamp was used. Partially reduced iron oxide and cerium oxide have the water splitting ability, respectively. So, $Fe_3O_4$ supported on $CeO_2$ was selected as the active material. $Fe_3O_4/CeO_2$(20 wt/80 wt%) was prepared by impregnation method, then the active material was washcoated on the ceramic honeycomb monolith made of mullite and cordierite. Oxygen was released at the reduction step($1673{\sim}1823\;K$) and hydrogen was produced from water at lower temperature($873{\sim}1273\;K$). The result demonstrate the possibility of the 2-step thermochemical water splitting hydrogen production by the active material washcoated monolith. And hydrogen and oxygen was produced separately without any separation process in a monolith installed reactor. But the SEM and EDX analysis results revealed that the support used in this experiment is not suitable due to the thermal instability and coating material migration.

Hydrogen Production with High Temperature Solar Heat Thermochemical Cycle using CeO2/ZrO2 Foam Device (CeO2/ZrO2 Foam Device를 이용한 고온 태양열 열화학 싸이클의 수소 생산)

  • Lee, Jin-Gyu;Seo, Tae-Beom
    • Journal of the Korean Solar Energy Society
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    • v.34 no.6
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    • pp.11-18
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    • 2014
  • Two-step water splitting thermochemical cycle with $CeO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2$ foam device depending on reaction temperature of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. As a result, the amount of reduced $CeO_2$ considerably varies according to the reaction temperature of Thermal-Reduction step. and hydrogen production was not much when the amount of reduced $CeO_2$ decreased even if the reaction temperature of Water-Decomposition step was high. Therefore, it is very important to keep the reaction temperature of Thermal-Reduction step high in two-step thermochemical cycle with $CeO_2$.

Partial Reduction and Water Splitting Characteristics of Metal Substituted Ferrite Mediums for Thermochemical Hydrogen Production (열화학 수소 제조를 위한 금속 치환 페라이트 매체의 부분 환원 및 물 분해 특성)

  • Lee, Dong-Hee;Kim, Hong-Soon;Cha, Kwang-Seo;Park, Chu-Sik;Kang, Kyung-Soo;Kim, Young-Ho
    • Transactions of the Korean hydrogen and new energy society
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    • v.18 no.4
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    • pp.356-364
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    • 2007
  • The partial reduction and water splitting properties of metal substituted ferrite mediums for two-step thermochemical hydrogen production, were carried out by TPR/O(Temperature programmed reduction/oxidation) method at a temperature of below 1173 K and under atmospheric pressure. $ZrO_2$ was added to the ferrite as a binder to prevent the sintering. As the results, the reactivity of the metal species added to the ferrite mediums decreased in the order of Cu>Co>Ni>Mn, on the basis of water-splitting temperature. It was also found that the produced hydrogen amounts in the water-splitting step on partial reduced mediums were corresponding to the consumed hydrogen amounts in the previously partial reduction step.

The Characteristics of Solar Thermochemical Methane Reforming using Ferrite-based Metal Oxides (페라이트계 금속산화물을 이용한 태양 열화학 메탄 개질 특성)

  • Cha, Kwang-Seo;Lee, Dong-Hee;Jo, Won-Jun;Lee, Young-Seok;Kim, Young-Ho
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.06a
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    • pp.45-48
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    • 2007
  • Thermochemical 2-step methane reforming, involving the reduction of metal oxide with methane to produce syn-gas and the oxidation of the reduced metal oxide with water to produce pure hydrogen, was investigated on ferrite-based metal oxide mediums and $WO_{3}/ZrO_{2}$. Thermochemical 2-step methane reforming were accomplished at 900 $^{\circ}C$(syn-gas production step) and 800 $^{\circ}C$(water-splitting step). In syn-gas production step, it appeared carbon deposition on metal oxides with increasing react ion time. Various mediums showed the different starting point of carbon deposition each other. To minimize the carbon deposition, the reaction time was controlled before the starting point of carbon deposition. As a result, $CO_{x}$ were not evolved in water-splitting step, Among the various metal oxides, $Mn-ferrite/ZrO_{2}$ showed high reactivity, proper $H_{2}/CO$ ratio, high selectivity of undesired $CO_{2}$ and high evolution of $H_{2}$.

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TWO-STEP THERMOCHEMICAL CYCLES FOR HYDROGEN PRODUCTION WITH DISH TYPE SOLAR THERMAL SYSTEM and $CeO_2/NiFe_2O_4$ (접시형 태양열 집광 시스템과 산화세륨 및 페라이트산화물을 이용한 열화학 사이클의 수소생산)

  • Kwon, Hae-Sung;Oh, Sang-June;Seo, Tae-Beom
    • 한국태양에너지학회:학술대회논문집
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    • 2012.03a
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    • pp.113-119
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    • 2012
  • The two-step water splitting thermochemical cycle is composed of the T-R (Thermal Reduction) and W-D (Water Decomposition) steps. The mechanism of this cycle is oxidation-reduction, which produces hydrogen. The reaction temperature necessary for this thermochemical cycle can be achieved by a dish-type solar thermal collector (Inha University, Korea). The purpose of this study is to validate a water splitting device in the field. The device is studied and fabricated by Kodama et al (2010, 2011). The validation results show that the foam device, when loaded with $CeO_2$ powder, was successfully achieved hydrogen production under field conditions. Through this experiment, we can analyze the characteristics of the catalyst and able to determine which is more advantageous thing to produce hydrogen compared with previous experiment that used ferrite-device.

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A Study on Hydrogen Production with High Temperature Solar Heat Thermochemical Cycle by Heat Recovery (열회수에 따른 고온 태양열 열화학 싸이클의 수소 생산에 관한 연구)

  • Cho, Ji-Hyun;Seo, Tae-Beom
    • Journal of the Korean Solar Energy Society
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    • v.37 no.2
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    • pp.13-22
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    • 2017
  • Two-step water splitting thermochemical cycle with $CeO_2/ZrO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2/ZrO_2$ foam device depending on heat recovery of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2/ZrO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. Resultantly, the quantity of hydrogen generation increased by 52.02% when the carrier gas of Thermal-Reduction step is preheated to $200^{\circ}C$ and, when the $N_2/steam$ is preheated to $200^{\circ}C$ in the Water-Decomposition step, the quantity of hydrogen generation increased by 35.85%. Therefore, it is important to retrieve the heat from the highly heated gases discharged from each of the reaction spaces in order to increase the reaction temperature of each of the stages and thereby increasing the quantity of hydrogen generated through this.

Thermodynamic Analysis of Thermochemical Process for Water Splitting (고온열 이용 공정의 열역학적 해석)

  • Kim, Jong-Won;Son, Hyun-Myung;Lee, Sana-Ho;Sim, Kyu-Sung;Jung, Kwang-Deog
    • Transactions of the Korean hydrogen and new energy society
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    • v.13 no.3
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    • pp.204-213
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    • 2002
  • In this work, hydrogen production by a 2-step water-spritting thermochemical cycle based on metal oxides redox pairs was investigated on the bases of the thermodynamics and technical feasibility. Also, a 2nd-law analysis performed on the closed cyclic process indicates a maximum exergy conversion efficiency of 7.1% when using a solar cavity-receiver operated at 2300K and air/Fe3O4 molar ratio = 10.

TWO-STEP THERMOCHEMICAL CYCLES FOR HYDROGEN PRODUCTION WITH DISH TYPE SOLAR THERMAL SYSTEM (접시형 태양열 집광 시스템을 이용한 열화학 사이클의 수소생산)

  • Kwon, Hae-Sung;Oh, Sang-June;Seo, Tae-Beom
    • 한국태양에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.169-176
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    • 2011
  • The two-step water splitting thermochemical cycle is composed of the T-R (Thermal Reduction)and W-D (Water Decomposition)steps. The mechanism of this cycle is oxidation-reduction, which produces hydrogen. The reaction temperature necessary for this thermochemical cycle can be achieved by a dish-type solar thermal collector (Inha University, Korea). The purpose of this study is to validate a water splitting device in the field. The device is studied and fabricated by Kodama et al (2010, 2011). The validation results show that the foam device, when loaded with $NiFe_2O_4/m-ZrO_2$powder, was successfully achieved hydrogen production with 9 (10 with a Xe-light solar simulator, 2009, Kodama et al.) repeated cycles under field conditions. Two foam device used in this study were tested for validation before an experiment was performed. The lab scale ferrite-conversion rate was in the range of 24~76%. Two foam devices were designed to for structural stability in this study. In the results of the experiments, the hydrogen percentage of the weight of each foam device was 7.194 and $9.954{\mu}mol\;g^{-1}$ onaverage, and the conversion rates 4.49~29.97 and 2.55~58.83%, respectively.

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Hydrogen Production with High Temperature Solar Heat Thermochemical Cycle Using Dual-zone Reactor and CeO2/ZrO2 Foam Device (Dual-zone reactor와 CeO2/ZrO2 Foam Device를 이용한 고온 태양열 열화학 싸이클의 수소 생산)

  • Cho, Ji-Hyun;Seo, Tae-Beom
    • Journal of the Korean Solar Energy Society
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    • v.37 no.5
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    • pp.27-37
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    • 2017
  • In this study, an artificial solar simulator composed of a 2.5 kW Xe-Arc lamp and mirror reflector was used to carry out the solar thermal two step thermochemical water decomposition cycle which can produce high efficiency continuous hydrogen production. Through various operating conditions, the change of hydrogen production due to the possibility of a dual-zone reactor and heat recovery were experimentally analyzed. Based on the reaction temperature of Thermal-Reduction step and Water-Decomposition step at $1,400^{\circ}C$ and $1,000^{\circ}C$ respectively, the hydrogen production decreased by 23.2% under the power off condition, and as a result of experiments using heat recovery technology, the hydrogen production increased by 33.8%. Therefore, when a thermochemical two-step water decomposition cycle is conducted using a dual-zone reactor with heat recovery, it is expected that the cycle can be operated twice over a certain period of time and the hydrogen production amount is increased by at least 53.5% compared to a single reactor.

Reaction Characteristics of Thermochemical Methane Reforming on Ferrite-Based Metal Oxide Mediums (페라이트계 금속 산화물 매체 상에서 열화학 메탄 개질 반응 특성)

  • Cha, Kwang-Seo;Lee, Dong-Hee;Jo, Won-Jun;Lee, Young-Seak;Kim, Young-Ho
    • Transactions of the Korean hydrogen and new energy society
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    • v.18 no.2
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    • pp.140-150
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    • 2007
  • Thermochemical 2-step methane reforming, involving the reduction of metal oxide with methane to produce syngas and the oxidation of the reduced metal oxide with water to produce pure hydrogen, was investigated on ferrite-based metal oxide mediums. The mediums, CoFZ, CuFZ, or MnFZ, were composed of the mixture of M(M=Co, Cu or Mn)-substituted ferrite as an active component and $ZrO_2$ as a binder, respectively. The WZ medium, composed of the mixture of $WO_3$ and $ZrO_2$, was also prepared to compare. With an addition of $ZrO_2$, the surface area of the mediums was slightly increased and the sintering of active components was greatly suppressed during the reduction. The higher reactivity of the reduced mediums for water splitting was confirmed by the temperature programmed reaction. From the results of the thermochemical 2-step methane reforming, the reactivity of $CH_4$ reduction and water splitting with ferrite-based metal oxide mediums was relatively higher than that with WZ, and the order of reactivity of the mediums was MnFZ>CoFZ>CuFZ>WZ.