• Title/Summary/Keyword: Gas sorption

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The Crystal Structure of Dehydrated Fully $Ag^+$-Exchanged Zeolite A Successively Treated with Ethylene and Bromine Vapor

  • Jeong, Mi-Suk;Jang, Se-Bok;Kim, Yang
    • Bulletin of the Korean Chemical Society
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    • v.15 no.11
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    • pp.940-944
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    • 1994
  • The crystal structure of an ethylene sorption complex of dehydrated $Ag_{12}-A $reacted with bromine vapor has determined by single-crystal X-ray diffraction techniques in the cubic space group of Pm3m at 22(l)$^{\circ}$C (a=12.180(2) ${\AA}$). The crystal was prepared by dehydration of $Ag_{12}$-A at 400 $^{\circ}$C and $2 {\times} l0^{-6}$ Torr for 2 days, followed by exposure to 200 Torr of ethylene gas at 24(l) $^{\circ}$C for 1 hr. After the ethylene gas was evacuated for 1 hr, the crystal was exposed to 180 Torr of bromine vapor at 24(l) $^{\circ}$C for 1.5 h. The structure was refined to the final error indices, $R_1=0.066\;and\;R_2$ (weighted)=0.055, using 137 independent reflections for which I>3${\sigma}$I. About 55% of the sodalite unit contain two 6-ring $Ag^+$ ions and the remaining 45% contain $Ag_6$ molecules complexed to 2 $Ag^+$ ions at 6-ring sites to give $(Ag^+)_2(Ag_6).$ Upon sorption of ethylene, 4.75 ethylene molecules were sorbed per unit cell and of these, only 1.25 ethylene molecules were brominated by treatment of dibromine because of the limitation of the available space for the reaction products in the large cavity. In the large cavity, each of 3.5 $Ag^+$ ions forms a lateral ${\pi}$ complex with an ethylene molecule. About 2.5 8-ring $Ag^+$ ions per unit cell interact with 1.25 1,2-dibromoethane and each of ca. 1.25 6-ring $Ag^+$ ions also interacts with one of bromine atoms of 1,2-dibromoethane. Each bromine atom approaches a carbon atom with C-Br(l)=2.07(20) ${\AA}$ and C-Br(2)=2.07(10) ${\AA}$, respectively.

Development of Volume Modified Sorption Model and Prediction for Volumetric Strain of Coal Matrix (흡착에 의한 석탄암체의 부피변화가 고려된 흡착모델 개선 및 부피변형률 예측)

  • Kim, Sang-Jin;Sung, Won-Mo
    • Journal of the Korean Institute of Gas
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    • v.19 no.2
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    • pp.37-44
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    • 2015
  • We proposed the improved Langmuir adsorption relations considering volume change effect of coal matrix during primary production of CBM and Enhanced-CBM with injection of carbon dioxide or CCS in coalseam but also volumetric strain. To verify this model, experimental data of pure gas adsorption such as $CO_2$, $CH_4$, and $N_2$ on coals were used to compare conventional Langmuir model with this model. From the results, we obtained that the larger adsorption capacity of coal and the higher adsorption affinity of gas, the larger error occur with Langmuir model. Using this model, however, we found not only substantially better fit in all condition but also reasonable volumetric strain of the coal matrix. We also applied this volume modified pure gas adsorption model to the IAS model to describe gas adsorption and volumetric strain for mixed gas. This modified-IAS model fitting experimental data by Hall et al(1994) improved accuracy of mixed gas adsorption calculation compared with conventional model.

Selection of Process Configuration and Operating Conditions for SEWGS System (회수증진 수성가스화 시스템의 공정구성 및 조업조건 선정)

  • Ryu, Ho-Jung
    • Journal of Hydrogen and New Energy
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    • v.20 no.2
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    • pp.168-178
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    • 2009
  • To check feasibility of SEWGS(Sorption Enhanced Water Gas Shift) system, conceptual design and sensitivity analysis of operating variables have been investigated based on a design program of two-interconnected fluidized bed. Based on the conceptual design results, the optimum configuration for SEWGS was considered. Among three configurations, bubbling beds system was selected as the best configuration. Process design results indicate that the SEWGS system is compact and feasible. Based on the selected operating conditions, the effects of variables such as pressure, $CO_2$ capture capacity, solid inventory, CO conversion and $CO_2$ capture efficiency have been investigated as well.

Development of Solid Separator for Selective Solid Circulation in Two-interconnected Fluidized Beds System (2탑 유동층 시스템에서 선택적 고체순환을 위한 고체분리기 개발)

  • Ryu, Ho-Jung;Park, Young Cheol;Lee, Seung-Yong;Kim, Hong-Ki
    • Korean Chemical Engineering Research
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    • v.47 no.2
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    • pp.195-202
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    • 2009
  • As a basic research of developing two-interconnected fluidized beds system for selective solid circulation, a solid separator was developed to separate fine and coarse particles by means of particle size difference with particle size separation system equipped with metal screen. The effects of gas velocity, height of solid separator, and separation area on the solid separation rate were investigated as well. The solid separation rate increased as the gas velocity, height of solid separator, and separation area increased. As the gas velocity and height of the solid separator increased, the variation of the solid separation rate was consistent with that of bubble size. Consequently, coarse($212{\sim}300{\mu}m$) and fine($63{\sim}106{\mu}m$) particles were separated using the solid separator and the solid separation rate was ranged from 4.4 to 127 g/min. We also proposed two interconnenced fluidized beds system for sorption enhanced water-gas shift process equipped with the developed solid separator.

The Influence of Support on Gas Mask Cobalt Catalysts for Low Temperature CO Oxidation (방독마스크용 코발트 촉매의 저온 일산화탄소 산화반응에서 지지체의 영향)

  • Kim, Deog-Ki;Kim, Bok-Ie;Shin, Chae-Ho;Shin, Chang-Sub
    • Journal of the Korean Society of Safety
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    • v.21 no.2 s.74
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    • pp.35-45
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    • 2006
  • Cobalt catalysts for gas mask loaded on various supports such as $Al_{2}O_{3},\;TiO_{2}$, AC(activated carbon) and $SiO_{2}$ were used to examine influences of calcination temperatures and reaction temperatures for CO oxidation. $Co(NO_{3})_2{\cdot}6H_{2}O$ was used as cobalt precursor and the catalysts were prepared by incipient wetness impregnation. The catalysts were characterized using XRD, TGA/DTA, TEM, $N_{2}$ sorption, and XPS. For the catalytic activity, support was in the order of ${\gamma}-Al_{2}O_{3}>TiO_{2}>SiO_{2}>AC\;and\;Al_{2}O_{3}$. The catalytic activity at lower temperature than $80^{\circ}C$ showed that with the increase of reaction temperature, cobalt catalysts on ${\gamma}-Al_{2}O_{3},\;TiO_{2},\;AC\$ has the negative activation energy but that of $SiO_{2}$ was positive.

Studies on Food Preservation by Controlling Water Activity 1. Measurement of Sorption Isotherm of Dried Filefish Muscle by Equilibration in Dynamic Stream of Conditioned Air (식품보장과 수분활성에 관한 연구 1. 조절기류에 의한 건조말쥐치육의 등온흡습곡선의 측정)

  • HAN Bong-Ho;CHOI Soo-Il
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.14 no.4
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    • pp.189-193
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    • 1981
  • An apparatus for continuous measurements of sorption isotherm of dried food was manufactured to shorten the time required for equilibration. The apparatus was so designed that the temperature, air velocity and relative humidity in the experimental chamber could be controlled. The use of dynamic stream of conditioned air with a velocity of 0.2m/sec, instead of static atmosphere, allowed a faster equilibration of dried filefish muscle at $25^{\circ}C$. The mean time necessary for the equilibration of dried filefish muscle at the water activity of a given state to a higher water activity was about 45 hours. The monolayer moisture content of dried filefish muscle calculated from BET-equation was 0.092 kg water /kg dry matter at $25^{\circ}C$.

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Reaction Characteristics of WGS Catalyst for SEWGS Process in a Pressurized Fluidized Bed Reactor (가압 유동층 반응기에서 SEWGS 공정을 위한 WGS 촉매의 반응특성)

  • Kim, Ha-Na;Lee, Dong-Ho;Lee, Seung-Yong;Hwang, Taek-Sung;Ryu, Ho-Jung
    • Journal of Hydrogen and New Energy
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    • v.23 no.4
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    • pp.337-345
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    • 2012
  • To check effects of operating variables on reaction characteristics of WGS catalyst for SEWGS process, water gas shift reaction tests were carried out in a pressurized fluidized bed reactor using commercial WGS catalyst and sand(as a substitute for $CO_2$ absorbent) as bed materials. Simulated syngas(mixed with $N_2$) was used as a reactant gas. Operating temperature was $210^{\circ}C$ and operating pressure was 20 bar. WGS catalyst content, steam/CO ratio, gas velocity, and syngas concentration were considered as experimental variables. CO conversion increased as the catalyst content and steam/CO ratio increased. CO conversion at fluidized bed condition was higher than that of fixed bed condition. However, CO conversion were maintained almost same value within the fluidized bed condition. CO conversion decreased as the syngas concentration increased. The optimum operation condition was confirmed and long time water gas shift reaction test up to 24 hours at the optimum operating conditions was carried out.

Effect of the Number of Passes through Grinder on the Pore Characteristics of Nanofibrillated Cellulose Mat (그라인딩 처리 횟수에 따른 나노피브릴화 셀룰로오스 매트의 공극 특성)

  • Sim, Kyujeong;Ryu, Jaeho;Youn, Hye Jung
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.45 no.1
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    • pp.35-41
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    • 2013
  • In this study, we investigated the effect of the number of passes through agrinder on the pore characteristics of nanofibrillated cellulose (NFC) mat. The beaten pulp suspension was used to make NFC suspension using a grinder. To evaluate the pore characteristics of a NFC mat, the surface morphology of the dried NFC mat was observed with FE-SEM and the specific surface area was analyzed with BET nitrogen gas adsorption. The structure of NFC mat was changed with the different number of passes and drying methods. The specific surface area of NFC mat increased with the increase in the number of passes. The 20-passed NFC mat had 20 times larger specific surface area ($141m^2/g$) compared to the 0-passed NFC mat. The specific surface area was strongly correlated with the average pore size in NFC mat. The average pore diameter in NFC mat was calculated from the gas sorption isotherms using BJH model. The value was 13 - 15 nm, indicating that the NFC mat had mesoporous structure.

Fabrication and NOx Sensing Characteristics of $WO_{3}$ Based Thick Film Devices Doped with $TiO_{2}$ and Noble Metals ($TiO_{2}$와 귀금속을 첨가한 $WO_{3}$ 후막 센서의 제조 및 NOx 감응 특성)

  • Lee, Dae-Sik;Han, Sang-Do;Son, Young-Mok;Lee, Duk-Dong
    • Journal of Sensor Science and Technology
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    • v.6 no.4
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    • pp.274-279
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    • 1997
  • NOx sensors using tungsten oxide films as a base material were prepared and their electrical and sensing characteristics have been investigated. The $WO_{3}$ thick films doped with $SnO_{2}$ or $TiO_{2}$ showed higher sensitivity and better sorption characteristics to NOx gas than the pure $WO_{3}$ films material in air at operating temperature of $400^{\circ}C$. By addition of noble catalysts, such as Ru or Au, to the $TiO_{2}-WO_{3}$ thick films, their sensitivity, recovery and selectivity to NOx gas were found to be more enhanced.

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Odor Removal by Using Compost and Granular Scrap Tires (퇴비 및 폐타이어 Granule을 이용한 악취 제거)

  • Chung, Yoon-Jin
    • Journal of Korean Society of Water and Wastewater
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    • v.13 no.1
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    • pp.43-50
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    • 1999
  • In spite of low energy requirement, and operation and construction cost, biofilters with soil beds have not been operated efficiently. Because of excess moisture in winter and rainy periods, saturated pores in the bed prevent passage and sorption of odorous compounds. Sometimes this results in septic conditions that release previously sorbed and oxidized sulfur. Therefore, an economical and effective alternative needs to be developed. The objectives of this study were to confirm applicability of the granular scrap tires with compost for treating odorous gas as well as to obtain optimum design parameters for proposed system. In lab-scaled test, multiple stage reactors had lower headloss than a single stage reactor and less headloss was occurred for the gas with higher moisture content. For practical purpose, pilot-scaled reactor was operated to remove odor from septic tank, manure and animal wastewater treatment plant and composting machine. According to the results of pilot scaled test, $H_2S$ can be always removed completely and ammonia/amine can be removed excellently when proper moisture content is provided. The results from lab and pilot test showed that granular scrap tire could be replaced with soil as supporting material for biofilter showed excellent drainage because of its ability to reject moisture.

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