• Resources Recycling
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• v.31 no.6
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• pp.52-59
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• 2022

Calcium silicate based cement (CSC) is a low-carbon cement that emits less CO₂ by up to 70% compared to ordinary Portland cement during its manufacture. Most developed countries have commercialized CSC, whereas Korea is still investigating the manufacturing characteristics and basic properties of CSC. This paper provides a review of methods for manufacturing CSC using domestic raw materials and discusses the possibility of CSC localization based on an evaluation of the basic physical properties of manufactured CSC. The experimental results of this study indicate that the primary mineral components of CSC were CS, C₃S₂ C₂S, and unreacted SiO₂. This suggests the possibility of manufacturing CSC using domestic raw materials that exhibit mineral compositions similar to that of theoretical CSC. The compressive strength of CSC mortar is less than 1MPa at the age of 7 d under wet curing. This implies that hydration does not affect the property development of CSC mortar. Meanwhile, during carbonation curing, the compressive strength is 56 MPa or higher after 7 d, which indicates excellent early strength development. Furthermore, results of Thermogravimetric Analysis Differential scanning calorimetry (TG/DSC) show that a significant amount of CaCO₃ is formed, which is consistent with the results of previous studies. This implies that carbonation is associated significantly with the properties of CSC.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2263-2273
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• 2000

Catalytic wet air oxidation of acetic acid over Mn-Ce based catalysts deposited on various supports ($SiO_2$, $TiO_2$, $ZrO_2$), $ZrSiO_4$, $ZrO_2(10wt%)/TiO_2$) have been carried out in high pressure microreactors. Also, promotional effects by small addition(O.5~1.0 wt%) of p-type semiconductors (CoO, $Ag_2O$, SnO) have been investigated. From the screening tests for initial activity ranking, both Mn(2.8)-Ce(7.2 wt%) and Ru(O.4)Mn(2.7)-Ce(6.9 wt%) supported on $TiO_2$ were selected as the promising reference candidates. In $Mn-Ce/TiO_2$ reference catalyst, addition of small amount of each p-type semiconductor (Co, Sn and Ag) resulted in activity promotional effect and the degree of the increase was in the following order: Co> Ag > Sn. Especially, $Mn-Ce/TiO_2$ promoted with 0.5 wt% Co gave the 2.6 folds activity increase compared to the reference case attributing to the surface area increase as well as synergy effect. In $Ru-Mn-Ce/TiO_2$ reference catalyst, only Co(1.0 wt%) promoted case showed a little reaction rate increase.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.1233-1236
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• 2010

본 연구에서는 메탄을 물질로 산화실험을 수행하였다. 메탄의 발화온도가 탄화수소 중에 가장 높으며, 대부분의 전이금속촉매 활성온도가 가장 높게 나타나는 물질이므로 메탄의 연소가 일어날 경우 대부분의 탄화수소류는 연소가 일어날 수 있으므로 메탄의 산화반응을 연구하였다. 메탄의 산화를 위한 전이금속 촉매중 망간을 산화물형태로 $Al_2O_3$, $TiO_2$에 담지하여 메탄에 대한 활성능을 측정하였으며, 조촉매로 금속산화물을 이용하여 활성능의 변화를 연구하였다. 또한 자연에 존재하는 천연망간광석과 금속산화물을 담지하여 최적의 메탄에 대한 활성능을 지닌 촉매를 선별하였다. 조촉매로는 Ce, Sn, Ni, Co, Mo 등을 이용하였다. 또한 본 연구에서는 촉매 제조는 과잉용액함침법을 사용하여 담지체에 촉매물질을 분산하였으며, 온도와 유량에 대한 각 조성 촉매의 활성능을 측정하여 활성화에너지 및 $T_{50}$, $T_{90}$을 도출하였다.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.101-106
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• 1998

Two types of CoMo/zeolite as well as $NiMo/{\gamma}-Al_2O_3$ were prepared and their activities and selectivities of low-temperature dibenzothiophene(DBT) hydrodesulfurization(HDS) were studied in high pressure fixed bed reactor. The HDS activities of CoMo/zeolites were higher than that of $NiMo/{\gamma}-Al_2O_3$ at temperatures below $225^{\circ}C$ while they were lower than that of $NiMo/{\gamma}-Al_2O_3$ at temperatures higher than $275^{\circ}C$. The main products from $NiMo/{\gamma}-Al_2O_3$ were biphenyl and cyclohexylbenzene. The product distribution of CoMo/zeolite catalysts was different from that of $NiMo/{\gamma}-Al_2O_3$. It is speculated that DBT is converted to alkylcyclohexane over zeolite based catalysts through both alkylation and hydrogenation reactions. The crystal structure of molybdenum was $MoO_3$ in fresh zeolite support while mixtures of $MoO_3$ and $MoS_2$ were observed in the aged catalyst.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.61-64
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• 1997

1. 서론 : 적절한 이산화탄소의 분리는 지구온난화의 가속현상을 늦출 수 있을 뿐만 아니라 각종 탄화수소가스의 원료로 분리 정제된 이산화탄소를 재이용할 수 있으므로 경제적으로 매우 중요하다. 이산화탄소 분리에 사용되던 기존 공정들의 단점을 보완할 수 있는 대체방안으로 최근에 개발되기 시작한 것이 소수성의 다공성 고분자 분리막(hydrophobic porous ploymeric membrane) 방법인데, 이는 모듈의 유효 막 표면적이 상대적으로 크고 기체와 액체의 흐름을 독립적으로 제어할 수 있으므로 범람 등의 현상이 없으나 막 자체의 저항이 비교적 큰 단점을 가지고 있다. Qi와 Cussler는 이러한 특성을 가지는 중공사막 모듈에서의 기-액 흐름에 대한 물질전달 상관관계식을 얻었으며[1], Karoor 등은 여러 가지 중공사막 모듈을 사용하여 순수물과 diethanolamine(DEA) 등의 흡수제에 대한 이산화탄소의 물질전달 거동을 수치모델과 실험을 통하여 고찰하였다[3]. 또한 중공사막 접촉기의 실제적 응용에 대하여 Matsumoto 등은 화력발전소에서 발생하는 연소가스 내의 이산화탄소 흠수에 대한 연구를 수행하였다[4]. 본 연구에서는 중공사막 접촉장치를 사용하여 흡수제를 순수물과 탄산칼륨($K_2CO_3$)을 사용했을 경우의 이산화탄소의 분리 거동을 수치모델과 실험을 통하여 고찰하였다. 수치모델의 경우 이전까지의 연구가 반응이 없는 경우나 반응식을 간략화시킨 경우에 한정되었는데 비하여, 반으이 있는 경우 각각의 반응물질들의 거동을 고려한 반응식을 유도하여 해를 구하고자 하녔다.

• Membrane Journal
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• v.14 no.4
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• pp.275-288
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• 2004

Carbon dioxide was absorbed into water-in-oil (w/o) emulsion composed of aqueous 2-amino-2-methyl-1-propanol (AMP) droplets as a dispersed phase and benzene solutions of polybutene and polyisobutylene as a continuous phase in a flat-stirred vessel to investigate the effect of non-Newtonian rheological behavior on the rate of chemical absorption of $CO_2$, where the reaction between $CO_2$ and AMP in the aqueous phase was assumed to be a pseudo-first-order reaction. It was expressed that PIB with elastic property made the rate of chemical absorption of $CO_2$ accelerated by comparison of mass transfer coefficient of $CO_2$ in the non-Newtonian liquid with that in the Newtonian liquid.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.73.2-73.2
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• 2011

석탄 합성가스 중에는 $H_2S$, HCl, $NH_3$와 같은 불순물이 포함되어 있다. 이러한 가스들은 오염가스 배출과 관련한 환경기준 준수와 터빈과 같은 설비의 보호를 위해 제거되어야 한다. 석탄 합성가스 중 HCl 농도는 탄종에 따라 다르기는 하지만 많게는 1000 ppmv 수준까지 존재한다. 합성가스를 이용하여 발전을 하는 경우 가스터빈 보호를 위해 HCl은 <3 ppmv 이하로 정제되어야 하고, 합성가스를 연료전지에 사용하고자 하는 경우에는 HCl을 <0.5 ppmv 수준까지, 화학원료로 사용하고자 하는 경우에는 <10 ppbv 수준까지 정제하여야 한다. 또한 HCl은 고온 탈황공정에 사용되는 흡수제의 활성에도 장기적으로 부정적인 영향을 주기 때문에 고온에서 HCl을 정제할 수 있는 흡수제가 필요하다. 본 연구에서는 알칼리금속을 활성물질로 사용하여 분무건조법으로 제조한 HCl 흡수제에 대해 물성 및 HCl과의 반응성을 살펴보았다. $300-500^{\circ}C$ 영역에서 K-계 및 Na-계 흡수제에 대해 고정층반응기에서 HCl 가스를 함유한 모사 합성가스를 이용하여 상압 조건에서 Cl 흡수능을 측정한 결과 15wt% 이상의 흡수능을 나타내었으며 반응온도가 높을수록 흡수능이 증가함을 알 수 있었다. XRD 분석을 통하여 Cl은 K 및 Na와 반응하여 KCl과 NaCl을 형성하면서 흡수됨을 알 수 있었다. 20 bar 조건에서 실험한 결과에서도 동일한 경향의 반응성을 나타내었으며 반응온도가 낮을수록 흡수능은 감소하지만 Cl을 더 낮은 농도로 정제할 수 있었다. 본 실험에 사용된 Na 및 K계 흡수제는 모두 연소 후 배가스 중 $CO_2$를 제거하기 위한 흡수제로 사용되는 고체 흡수제이다. 석탄화력발전소 배가스에 연계되어 $CO_2$ 회수실험에 사용되었던 사용 후 $CO_2$ 흡수제에 대해 HCl 흡수 실험을 수행한 결과에서도 우수한 HCl 제거 성능을 보여 주었다. 이로부터, 폐 $CO_2$ 흡수제의 HCl 흡수제로서의 활용가능성을 확인 하였다.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.56-61
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• 2016

In this study, the effect of natural minerals on the reaction kinetics for lignite-$CO_2$ gasification was investigated. After physical mixing of lignite from Meng Tai area with 5 wt% of each natural mineral catalysts among Dolomite, Silica sand, Olivine and Kaolin, $CO_2$ gasification was performed using TGA at each 800, $850^{\circ}C$ and $900^{\circ}C$. The experimental data was analyzed with volumetric reaction model (VRM), shrinking core model (SCM) and modified volumetric reaction model (MVRM). MVRM was the most suitable among three models. As increasing the reaction temperature, the reaction rate constant became higher. With natural mineral catalysts, the reaction rate constant was higher and activation energy was lower than that of without catalysts. The lowest activation energy, 114.90 kJ/mol was obtained with silica sand. The highest reaction rate constant at $850^{\circ}C$ and $900^{\circ}C$ and lower reaction rate constant at $800^{\circ}C$ were obtained with Kaolin. Conclusively, the better catalytic performance could be observed with Kaolin than that of using other catalysts when the reaction temperature increased.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.3
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• pp.112-117
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• 2018

The metal alkoxide, CuCo-glycerate nanospheres (NSs), were successfully synthesized as Cu-Co bimetallic sulfides hierarchical multi-shelled hollow nanospheres ($CuCo_2S_4$ HMHNSs) through solvothermal synthesis. In this reaction mechanism, the solvothermal temperature and the amount of glycerol as a cosurfactant play significant role to optimize the morphology of CuCo-glycerate NSs. Furthermore, $CuCo_2S_4$ HMHNSs were obtained under optimized sulfurization reaction time of 10 h via anion exchange reaction between glycerate and sulfur ions. Finally, the structural and chemical compositions of CuCo-glycerate NSs and $CuCo_2S_4$ HMHNSs were confirmed through field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and electrochemical performances.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.803-810
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• 1998

We have studied the catalytic combustion of soot particulate over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution of metal into A or B site of perovskite oxide. In addition, the reaction conditions, such as temperature, $O_2$ concentration, space velocity have been studied. The effect of $SO_2$ pretreatment and water introduced into reactants were also examined. In the $LaCoO_3$ catalyst, the partial substitution of alkali metals into A site enhanced the catalytic activity in the combustion of soot particulate and the activity was shown in the order : Cs>K>Na; In the $La_{0.6}Cs_{0.4}CoO_3 $; catalyst, the substitution of Fe or Mn showed no effect on the ignition temperature. The ignition temperature decreased with increasing $O_2$ concentration and contact time. The introduction of water into reactants feed decreased the ignition temperature and the pretreatment of $SO_2$ showed no effect on the catalytic activity.