• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.387-390
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• 2008

Ni/MgAl 촉매상에서 LPG의 수증기 개질반응을 반응온도 $700{\sim}800^{\circ}C$, 공간속도 $20,000h^{-1}$, 수증기/탄소 비율 $1.0{\sim}3.0$인 조건으로 대기압하에서 수행하였다. 본 연구에서 사용된 촉매들은 공침법으로 제조하였으며, 하이드로탈사이트 구조에서 Ni-MgO 구조로 변환되는 과정에서 활성금속인 니켈이 고분산되는 장점을 지니고 있다. 제조된 촉매는 함침법으로 제조된 촉매보다 활성이 잘 유지되었으며 탄소침적에 대한 내구성 또한 향상되었으나 완벽하게 해결되지는 못하였다. 따라서 이와 같은 문제점을 해결하기 위해 귀금속이 modified된 Ni/MgAl 촉매를 제조하고 반응 특성을 비교하였다. Rh-Ni/MgAl 촉매는 LPG 수증기 개질 반응에서 1024시간동안 활성이 유지됨을 확인하였을 뿐만 아니라 탄소침적 또한 발생하지 않음을 확인하였다.

• Korean Journal of Chemical Engineering
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• v.36 no.2
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• pp.191-196
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• 2019

The phase of Cu,Zn,Al precursors strongly affects the activity of their final catalysts. Herein, the Cu,Zn,Al precursor was prepared by precipitation of $Al^{3+}$ onto primitive, amorphous Cu,Zn precipitate. This precursor turned out to be a phase mixture of zincian malachite and hydrotalcite in which the latter phase was less abundant compared to the co-precipitated precursor. The final catalyst derived from this precursor exhibited a little higher copper surface area and methanol synthesis activity than the co-precipitated counterpart. Therefore, the two precursor phases need to be mixed in an adequate proportion for the preparation of active $Cu/ZnO/Al_2O_3$ catalyst.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.653-657
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• 2009

Nitrous oxide is a typical greenhouse gas which is produced from various organic or fossil fuel combustion processes as well as chemicals producing plants. $N_2O$ has a global worming potential of 310 times that of $CO_2$ on per molecule basis, and also acts as an ozone depleting material in the stratosphere. However, its removal is not easy for its chemical stability characteristics. Most SCR processes with several effective reducing agents generally require the operation temperature higher than $450^{\circ}C$, and the catalytic conversion becomes decreased significantly when NOx is present in the stream. Present experiments have been performed to obtain basic design data of actual application concerning the effects of $SO_2$ and $NH_3$ on the interim and long term activities of $N_2O$ reduction with CO over the mixed metal oxide (MMO) catalyst derived from a hydrotalcite-like compound precursor. The MMO catalysts used in the experiments, have shown prominent activities displaying full conversions of $N_2O$ near $200^{\circ}C$ when CO is introduced. The presence of $SO_2$ is considered to show no critical behavior as can be met in the $NH_3$ SCR DeNOx systems and the effect of $NH_3$ is considered to play as mere an impurity to share the active sites of the catalysts.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.82-87
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• 2008

$N_2O$ decomposition characteristics of dual bed mixed metal oxide catalytic system was investigated. The partial oxidation of methane at first reactor of dual bed catalytic system was performed over Co-Rh-Al (1/0.2/1) catalyst under the optimized condition of $8,000h^{-1}$ GHSV, gas ratio ($CH_4:O_2=5:1$) at $500^{\circ}C$. In the dual bed system investigated herein, the second catalyst bed was employed for the $N_2O$ decomposition using product of partial oxidation of methane at first bed. An excellent $N_2O$ conversion activity even at lower temperature ($<250^{\circ}C$) was obtained with Co-Rh-Al (1/0.2/1) or Co-Rh-Zr-Al (1/0.2/0.3/1) catalyst by combining Co-Rh-Al (1/0.2/1) hydrotalcite catalyst for the partial oxidation of methane in a dual-bed system. The $N_2O$ conversion activity is drastically reduced in the presence of oxygen in second bed of a dual-bed system over Co-Rh-Al (1/0.2/1) catalyst at $300^{\circ}C$.

• Journal of Wetlands Research
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• v.24 no.2
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• pp.142-154
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• 2022

Arsenic (As) contamination in groundwater is one of the main problems in Bangladesh. As toxicity causes serious human health problems such as edema, skin cancer, bladder cancer, lung cancer, hyperkeratosis, premature birth, and black foot disease. As contamination in groundwater mainly originates from the geological characteristics of the area due to the influence of anthropogenic activities. Since most of the people in Bangladesh rely on tube well for drinking water, it is necessary to investigate the current status of As pollution and identify the treatment technologies that can be used to provide arsenic-free drinking water in water-scarce areas. A total of 92 papers were reviewed in this study to present a complete overview of the recent status of groundwater As contamination in Bangladesh and different low-cost remediation technologies. A method for evaluating the relative feasibility of different treatment technologies was also utilized to determine the most appropriate technologies for groundwater As treatment in Bangladesh. The districts with the highest groundwater As contamination include Brahamanbariya, Tangail, Barisal, Pabna, Patuakhali, Kurigram, Magura, and Faridpur, with concentrations exceeding 0.05 mg/L. Only six districts had relatively low groundwater arsenic concentrations (0.01 mg/L), including Kushtia, Khagrachari, Jessore, Dinajpur, Meherpur, and Munshiganj. There were a number of technologies used for treating As in water, but aerated electrocoagulation, Mg-Fe-based hydrotalcite-like compound, and electro-chemical As remediation (ECAR) reactor were found to be the most feasible treatment methods for As. Overall, the investment, operational, and maintenance costs, availability of materials, and expertise requirements should be considered when selecting the most appropriate treatment method for As in water.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.727-730
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• 2009

Highly active and stable nano-sized Ni catalysts supported on MgO-$Al_2O_3$ calcined from hydrotalcite-like materials have been successfully developed with a strong metal to support interaction (SMSI) to enhance the coke resistance in combined $H_2O$ and $CO_2$ reforming of $CH_4$ (CSCRM) for syngas ($H_2$/CO=2) production. The change of the surface area and NiO crystallite size with varying the pre-calcination temperature of support and Mgo content was investigated in relation to the coke resistance. As increasing the pre-calcination temperature, the surface area decreases and the metal to support interaction becomes weak. As a consequence, the coke deposition was more severe on catalysts pre-calcined at high temperature. It was concluded that highly dispersed Ni metal in the surface of Ni/MgO-$Al_2O_3$ catalyst (MgO=30 wt%) pre-calcined at $800^{\circ}C$ had a strong metal to support interaction (SMSI) resulting in an increase of coke resistance and high activity.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.745-748
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• 2009

수소는 지구상에 풍부하게 존재하는 원소로 최근 수소경제시대에 대한 기대와 함께 청정 에너지 carrier로 주목받고 있다. 본 연구에서는 고순도 수소 생산을 위해 water gas shift (WGS) 반응과 $CO_2$의 분리를 하나의 unit operation의 형태로 수행하는 신개념의 thermal swing sorption enhanced reaction (TSSER) 공정의 타당성을 테스트하는데 목적을 두고 있다. Le Chatelier 원리를 기본으로 하는 흡착분리 동시 반응 (sorption enhanced reaction, SER)에서는 수소생산 반응의 열역학적 한계를 극복할 수 있고 정반응의 속도를 증대시킬 수 있다. 본 연구에서는 $K_2CO_3$가 첨가된 hydrotalcite에 대한 고온에서의 $CO_2$ 화학흡착 평형 및 거동 데이터를 실험을 통하여 측정하였다. 또한 WGS 상용촉매와 화학 흡착제를 이용하여 흡착분리 동시 반응을 실험과 수치해석 시뮬레이션으로 수행하였고, 연구결과로부터 연료전지에 사용할 수 있는 고순도의 수소 (~10 ppm CO)를 직접 생산할 수 있으며, 동시에 고압상태의 $CO_2$를 고순도로 포집할 수 있음을 확인할 수 있었다. 고압, 고순도의 $CO_2$ 포집은 이후 $CO_2$ 저장에 용이하게 이용되어 온실가스 저감에 기여할 수 있을 것으로 기대된다.

• New & Renewable Energy
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• v.4 no.4
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• pp.80-87
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• 2008

Steam reforming of LPG was investigated over spc-Ni/MgAl catalyst in a temperature range of $600{\sim}850^{\circ}C$, feed molar ratio of $H_2O/C=1.0{\sim}3.0$, space velocity of $10,000{\sim}90,000h^{-1}$ and at atmospheric pressure. spc-Ni/MgAl catalyst was prepared by a co-precipitation method, whereas Ni/MgO and $Ni/Al_2O_3$ catalysts were prepared by an incipient wetness method. The characteristics of catalysts were analyzed by N2 Physisorption, CO chemisorption, XRD, TOF-SIMS, SEM and TEM techniques. The Ni/MgO and $Ni/Al_2O_3$ catalysts were deactivated by the formation of carbon. However, the spc-Ni/MgAl catalyst showed higher conversion and $H_2$ selectivity than the other catalysts, even though carbon was formed on the surface of the catalyst during the reaction under the tested reaction conditions.

• Corrosion Science and Technology
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• v.7 no.4
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• pp.212-218
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• 2008

Inorganic ion exchange compounds (IECs) including hydrotalcites and bentonite clays are a well known classes of layered mixed metal hydroxides or silicates that demonstrate ion exchange properties. These compounds have a range of applications from water purification to catalyst supports. The use of synthetic versions of these compounds as environmentally friendly additives to paints for storage and release of inhibitors is a new and emerging application. In this paper, the general concept of storage and release of inhibiting ions from IEC-based particulate pigments added to organic coatings is presented. The unique aspects of the IEC structure and the ion exchange phenomenon that form the basis of the storage and release characteristic are illustrated in two examples comprising an anion exchanging hydrotalcite compound and a cation exchanging bentonite compound. Examples of the levels of corrosion protection imparted by use of these types of pigments in organic coatings applied to aluminum alloy substrates is shown. How corrosion inhibition translates to corrosion protection during accelerated exposure testing by organic coatings containing these compounds is also presented.

• Corrosion Science and Technology
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• v.21 no.3
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• pp.221-229
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• 2022

To understand effects of cooling rates of coating layer on microstructures and corrosion behaviors of hot-dip alloy coated steel sheets (Zn-5%Al-2%Mg) in a neutral aqueous condition with chloride ion, a range of experimental and analytical methods were used in this study. Results showed that a faster cooling rate during solidification decreased the fraction of primary Zn, and increased the fraction of Zn-Al phase. In addition, interlamellar spacing became refined under a faster cooling rate. These modifications of the coating structure had higher open circuit potentials (OCP) with smaller anodic and cathodic current densities in the electrochemical potentiodynamic polarization. Surface analyses after a salt spray test showed that the increase in the Zn-Al phase in the coating formed under a faster cooling rate might have contributed to the formation of simonkolleite (Zn₅(OH)₈Cl₂·H₂O) and hydrotalcite (ZnAl₂(OH)₆Cl₂·H₂O) with a protective nature on the corroded outer surface, thus delaying the formation of red rust.