Strain-Induced Tailoring of Oxygen-Ion Transport in Highly Doped CeO₂ Electrolyte: Effects of Biaxial Extrinsic and Local Lattice Strain

Ahn, Junsung,Choi, Sungjun,Yoon, Kyung Joong,Son, Ji-Won,Kim, Byung-Kook,Lee, Jong-Ho,Jang, Ho Won,Kim, Hyoungchul American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.49

<P>We explored oxygen-ion transport in highly doped CeO2 through density-functional theory calculations. By applying biaxial strain to 18.75 mol % Ceo(2):Gd, we predicted the average migration-barrier energy with six different pathways, with results in good agreement with those of experiments. Additionally, we found that the migration-barrier energy could be lowered by increasing the tetrahedron volume,, including the space occupied by the oxygen vacancy. Our results indicate that the tetrahedron volume can be expanded by larger codoliants, as well as biaxial tensile strain: Thus, the combination of thin-film structure and codoping could offer a new approach to accelerate oxygen-ion transport.</P>

Numerical analysis of an ion transport membrane system for oxy–fuel combustion

Shin, Donghwan,Kang, Sanggyu Elsevier 2018 APPLIED ENERGY Vol.230 No.-

<P><B>Abstract</B></P> <P>Ion transport membranes (ITM) have been studied as a promising air separation unit (ASU) technology for oxy–fuel combustion owing to their high oxygen permeability. Even though the power consumption of the ITM is lower than that of cryogenic ASU, it still consumes a high proportion of the overall system power.</P> <P>In this study, a numerical analysis of the ITM system has been conducted using Aspen Plus® to determine the optimal system design for minimizing the power consumption to separate oxygen from air. Since the oxygen permeation through the ITM is driven by the oxygen partial pressure gradient between feed and permeation side, three ITM systems that have different pressure gradients across the membrane have been presented and their performances compared. The effects of the contributing parameters, such as thickness, pressure, temperature, and air flow rate on the oxygen permeation rate have been investigated. ITM performances of the counter and parallel flow configurations have been compared. The system that operates under atmospheric pressure at the feed channel and under vacuum pressure at the permeate channel yields the lowest power consumption for obtaining the same oxygen permeation rate among other pressure conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermodynamic analysis of the ITM system. </LI> <LI> Development of a two dimensional numerical ITM model. </LI> <LI> Parametric analysis for the ITM. </LI> <LI> Performance comparison of the proposed system with two other ITM systems. </LI> </UL> </P>

Isothermal Charge Transport Properties of La_0.1Sr_0.9Co_0.8Fe_0.2O_3-δ by Blocking Cell Method

Im, Ha-Ni,Kim, In-Ho,Singh, Bhupendra,Jeon, Sang-Yun,Yoo, Young-Sung,Song, Sun-Ju The Electrochemical Society 2017 Journal of the Electrochemical Society Vol.164 No.4

<P>In this work, we investigated charge transport properties of La0.1Sr0.9Co0.8Fe0.2O3-delta (LSCF1982) by a blocking cell experiment in isothermal conditions in 800-950 degrees C range. By measuring the ionic charge of transport (alpha(*)(i)) vs. oxygen partial pressure (pO(2)), the cross-effect between ionic and electronic flows were investigated. The values of alpha(*)(i) were found to be non-zero with a magnitude of 0.43-1.15 in 800-950 degrees C range, indicating that even in the absence of a direct cause of electron flow a significant number of electrons are dragged by the cations. By constructing an Onsager matrix, the values of Onsager transport coefficients were extracted. It was observed that the Onsager coefficients related with the cross-effect (L-ie = L-ei) have nearly of the same order of magnitude that of the Onsager coefficient for ionic flow (L-ii) and therefore cannot be ignored. The values of partial ionic conductivity were calculated from Onsager matrix and which showed an exponential increase (sigma O-2-alpha pO(2)(m), m = 1/2) with increasing pO(2) and temperature at 800 degrees C but less dependence on pO(2) at the higher temperatures. (C) 2017 The Electrochemical Society. All rights reserved.</P>

Oxygen permeation performance of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane after surface modification

Jung Hoon Park,Edoardo Magnone,Jong Pyo Kim,Soo Hyun Choi 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.2

The effect of minor surface modification on the performance of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane was evaluated in the temperature region from 700 to 850 oC. Oxygen permeation experiments were conducted according to membrane thickness (1.0mm and 1.6 mm) and oxygen partial pressure (0.21, 0.42, and 0.63 atm) in the absence and in the presence of carbon dioxide (300 and 500 ppm). The oxygen permeation flux of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane increased with increasing temperature and decreasing membrane thickness. The oxygen permeation flux through the membrane of 1.0 mm thickness with Ba0.5Sr0.5Co0.8Fe0.2O3−δ-modified surface was ca. 1.23 ml/cm2·min at 850 oC under air feeding condition. It was found that the Ba0.5Sr0.5Co0.8Fe0.2O3−δ-modified Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane has better oxygen permeation flux than the pristine Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane. In summary, it has been demonstrated that the surface morphology is an important factor in determining the oxygen permeation fluxes through Ba0.5Sr0.5Co0.8Fe0.2O3−δmembrane under mixed-control conditions.

Effect of B-Cation Doping on Oxygen Vacancy Formation and Migration in LaBO3: A Density Functional Theory Study

권혁규,박진우,김병국,한정우 한국세라믹학회 2015 한국세라믹학회지 Vol.52 No.5

LaBO3 (B = Cr, Mn, Fe, Co, and Ni) perovskites, the most common perovskite-type mixed ionic-electronic conductors (MIECs), are promising candidates for intermediate-temperature solid oxide fuel cell (IT-SOFC) cathodes. The catalytic activity on MIECbased cathodes is closely related to the bulk ionic conductivity. Doping B-site cations with other metals may be one way to enhance the ionic conductivity, which would also be sensitively influenced by the chemical composition of the dopants. Here, using density functional theory (DFT) calculations, we quantitatively assess the activation energies of bulk oxide ion diffusion in LaBO3 perovskites with a wide range of combinations of B-site cations by calculating the oxygen vacancy formation and migration energies. Our results show that bulk oxide ion diffusion dominantly depends on oxygen vacancy formation energy rather than on the migration energy. As a result, we suggest that the late transition metal-based perovskites have relatively low oxygen vacancy formation energies, and thereby exhibit low activation energy barriers. Our results will provide useful insight into the design of new cathode materials with better performance.

Effect of B-Cation Doping on Oxygen Vacancy Formation and Migration in LaBO₃: A Density Functional Theory Study

Kwon, Hyunguk,Park, Jinwoo,Kim, Byung-Kook,Han, Jeong Woo The Korean Ceramic Society 2015 한국세라믹학회지 Vol.52 No.5

$LaBO_3$ (B = Cr, Mn, Fe, Co, and Ni) perovskites, the most common perovskite-type mixed ionic-electronic conductors (MIECs), are promising candidates for intermediate-temperature solid oxide fuel cell (IT-SOFC) cathodes. The catalytic activity on MIEC-based cathodes is closely related to the bulk ionic conductivity. Doping B-site cations with other metals may be one way to enhance the ionic conductivity, which would also be sensitively influenced by the chemical composition of the dopants. Here, using density functional theory (DFT) calculations, we quantitatively assess the activation energies of bulk oxide ion diffusion in $LaBO_3$ perovskites with a wide range of combinations of B-site cations by calculating the oxygen vacancy formation and migration energies. Our results show that bulk oxide ion diffusion dominantly depends on oxygen vacancy formation energy rather than on the migration energy. As a result, we suggest that the late transition metal-based perovskites have relatively low oxygen vacancy formation energies, and thereby exhibit low activation energy barriers. Our results will provide useful insight into the design of new cathode materials with better performance.

이온전도성 분리막을 이용한 산소분리 연구동향

박정훈 ( Jung Hoon Park ),김종표 ( Jong Pyo Kim ) 한국공업화학회 2011 공업화학전망 Vol.14 No.3

연소전 및 산소연소 CO2 포집 기술로 적용 가능한 이온전도성 분리막 이용 산소제조 기술에 대해 소재, 모듈 및 공정에 대한 국내.외의 기술 동향 및 향후 전망에 관해 알아보았다. 현재는 고온영역에서 구동되는 분리막 조성을 중심으로 개발되고 있으나 향후 중저온 영역에서 운전가능한 산소분리막이 개발될 것으로 전망되며, 아울러 단위 반응기 부피당 투과 분리막 면적을 증가시키고, 재료비를 감소시킬 수 있는 중공사막을 이용한 모듈 개발이 가속화 될 것으로 기대된다.

순산소 연소용 이온 교환 막 시스템의 수치해석 연구

신동환(Donghwan Shin),강상규(Sanggyu Kang) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

Since the Ba<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Co<SUB>0.8</SUB>Fe<SUB>0.2</SUB>O<SUB>3-δ</SUB> membranes have the high oxygen permeability, which is widely used for the ion transport membrane(ITM). However, in order for the BSCF membranes to be commercialized as an air separation unit, its stability should be highly enhanced. Many researchers have been focused on the increase of the stability of the BSCF membranes. The performance of the ITM is affected by many geometric and operating parameters. The correlation between the parameters and the performance of the ITM should be investigated for the ITM system optimization. In this study, a numerical study on the ITM system has been conducted by using the Aspen Plus<SUP>®</SUP>. The ITM system is composed of ITM, heat exchanger, heater, cooler, vacuum pump, turbine and compressor. Two dimensional ITM model has been developed to capture the ITM characteristics more accurately. The ITM model has been discretized into 3 control volumes of feed channel, membrane, and permeate channel in the flow perpendicular direction to capture the oxygen transfer rate from the feed side to the permeate side. In order to capture the distribution of the oxygen transfer rate through the ITM, the ITM model has been discretized into 10 control volumes along the air flow direction. The ITM model has been validated by comparison with the published data. The ITM system model has been simulated by varying the pressure of the feed and permeate side.

순산소 연소시스템 이용 CO₂ 회수 기술 개발

박정훈(Jung Hoon Park),백일현(IL Hyun Baek),노동순(Dong-Soon Noh),이대근(Dae Keun Lee) 한국에너지기후변화학회 2007 에너지기후변화학회지 Vol.2 No.1

Carbon dioxide capture and storage (CCS) technologies are considered as one of the options to reduce atmospheric concentration of CO₂, Among these technologies, oxy-fuel combustion technology is being developed to capture a large amount of carbon dioxide emitted especially in electric generation and combustion system, Because oxy-fuel combustion technology is in the phase of demonstration contrary to pre- and post-combustion technology, many unit processes such as ASU and CO₂ recycle are being studied to develop more economical processes and to easily capture carbon dioxide. 10n transport membrane process to separate oxygen from the air is being developed as an emerging technology to reduce the O₂ producing cost, though cryogenic process is already commercialized, In addition, several worldwide projects on the oxy-fuel combustion have been launched to demonstrate CO₂ recovery by 2008 or 2011. In Korea, CO₂ recycle and burner technology of oxy-fuel combustion as well as ion transport membrane are being studied since 2002 supported from 21<SUP>st</SUP> century CO₂ frontier program and pulverized coal-oxygen / CO₂ recyle bumer of 100 ㎾-class and test facility were established.

La0.6Sr0.4B0.2Fe0.8O3-δ(B=Co, Ti) 분리막의 산소투과특성 및 안정성 비교

김종표(Jong Pyo Kim),박정훈(Jung Hoon Park),김기영(Ki Young Kim) 한국에너지기후변화학회 2007 에너지기후변화학회지 Vol.2 No.2

La0.6Sr0.4B0.2Fe0.8O3-δ(B=Co, Ti) oxide was synthesised by citric acid method and polymerized complex method respectively. Dense membranes of perovskite oxide have been prepared using as prepared powder by pressing and sintering at 1,300℃. Precursor was investigated by TGA and XRD. La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF-6428) was showed SrCO3 existed as impurity at 850°C, however indicated single phase perovskite structure at 1300℃. On the other hand, La0.6Sr0.4Co0.2Fe0.8O3-δ(LSTF-6428) was showed single phase perovskite structure at above than 800℃. The oxygen was permeated at temperatures from 700℃ to 950℃ by mixed conducting through oxygen vacancy diffusion in the dense membrane. The oxygen permeation flux increased with increasing temperature. In the result of LSCF-6428 was measured higher than LSTF-6428 to be 0.46 ㎖/minㆍ㎠ at 950℃. La0.6Sr0.4Co0.2Fe0.8O3-δ(B=Co, Ti) membrane after oxygen permeation were maintained perovskite structure and the surface of permeate-side was showed intact grain boundary.