• Clean Technology
• /
• v.18 no.3
• /
• pp.229-249
• /
• 2012

At present, global warming and depletion of fossil fuels have been one of the big issues which should be solved for sustainable development in the future. CCS (carbon capture and sequestration) technology as the post $CO_2$ reduction technology has been considered as a promising solution for global warming due to increased carbon emission. However, the environmental and ecological effects of CCS have drawn concerns. There are needs for noble post reduction technology. More recently, CCU (carbon capture and utilization) Technology, which emphasizes transforming carbon dioxide into value-added chemicals rather than storing it, has been attracted attentions in terms of preventing global warming and recycling the renewable carbon source. In this paper, various technologies developed for carbon dioxide conversion both in gas and liquid phase have been reviewed. For the thermochemical catalysis in gas phase, the development of the catalytic system which can be performed at mild condition and the separation and purification technology with low energy supply is required. For the photochemical conversion in liquid phase, efficient photosensitizers and photocatalysts should be developed, and the photoelectrochemical systems which can utilize solar and electric energy simultaneously are also in development for more efficient carbon dioxide conversion. The energy needed in CCU must be renewable or unutilized one. CCU will be a key connection technology between renewable energy and bio industry development.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.445.2-445.2
• /
• 2014

표면 조직화의 목적은 태양전지 표면에서의 입사되는 빛의 반사율을 감소 시키고, 웨이퍼 내에서 빛의 통과 길이를 길게 하며, 흡수되는 빛의 양을 증가시키는 것이다. 본 연구에서는 여러 가지 표면 조직화 공정 기술을 이용하여 표면 형상에 따른 광 변환 효율에 대해 연구하였으며, 셀을 제작하여 전기적 특성과 광학적 특성의 상관관계를 분석하였다. KOH를 이용한 표면 조직화, 산 증기를 이용한 표면 조직화, 반응성 이온 식각을 이용한 표면 조직화, 금속 촉매 반응을 이용한 표면 조직화 공정 기술을 이용하여 표면 조직화 공정을 진행하였다. 셀 제작 결과, 반사도 결과와는 상반되는 결과를 얻을 수 있었다. 표면 조직화 형상에 따른 셀 효율의 변화는 도핑 프로파일과 표면 재결합 속도의 변화 때문이라 생각되며 더 명확한 분석을 위해 양자 효율을 측정하여 분석을 시도하였다. 표면 조직화 공정 기술별 도핑 프로파일을 보면 KOH를 이용한 표면 조직화 공정을 제외한 나머지 표면 조직화 공정들의 도핑 프로파일은 불균일하게 형성되어 있는 것을 확인 할 수 있다. 양자 효율 측정 결과 단파장 대역에서 낮은 응답특성을 가지는 것을 확인 할 수 있었다. 그 이유는 낮은 반사도를 가지는 표면 조직화 공정의 경우 나노사이즈의 구조를 갖기 때문에 균일한 도핑 프로파일을 얻지 못해 전자, 정공의 분리가 제대로 이루어지지 못하였고 표면 재결합 속도증가의 원인으로 단락전류와 개방전압이 낮아져 효율이 떨어진 것으로 판단된다. 결과적으로 낮은 반사율을 갖는 표면 조직화 공정도 중요하지만 표면 조직화 공정 기술에 따른 균일한 도핑 프로파일을 갖는 공정을 개발한다면 단파장 응답도가 향상되어 단락전류밀도와 개방전압 상승효과를 얻을 수 있을 것이라 판단된다.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.5
• /
• pp.447-452
• /
• 2017

A $Pd/TiO_2$ catalyst was prepared by a conventional impregnation method, and further characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis spectroscopy. The as-prepared material was employed to accelerate dehydrogenation of potassium formate in the presence of light at different temperatures. The $Pd/TiO_2$ catalyst showed distinct dehydrogenation activities, and particularly, the material exhibited a higher turnover frequency (TOF) of $2,097h^{-1}$ at $80^{\circ}C$ after 10 minutes in the presence of light compared to that (TOF of $1,477h^{-1}$) obtained in the absence of light. Numerous analytical techniques suggest that the increased dehydrogenation activity likely originates from light-excited electron and hole at the photocatalyst, i.e., $TiO_2$, in conjunction with metal-support interaction.

• Polymer(Korea)
• /
• v.27 no.1
• /
• pp.3-8
• /
• 2003

Polysiloxanes with methacrylate groups at both terminals were synthesized by a hydrosilylation reaction between allyl methacrylate and hydride-terminated polysiloxanes. The polysiloxane methacrylates with high molecular weights could be prepared through the reaction of polysiloxane methacrylates and octamethylcyclotetrasiloxane with an acid catalyst. The structures of the prepared polysiloxane methacrylates were verified by $^1$H- and $^{29}Si-NMR.$ The polysiloxane methacrylates were freely miscible with silicone oils. Polysiloxane films with microphase-separated liquid silicone oil were prepared by photo-crosslinking the mixture of polysiloxane methacrylates and silicone oil. Scanning electron microscopy (SEM) of the films showed that the size of silicone oil droplets became smaller with a lower loading of silicone oil, lower molecular weight of polysiloxane methacrylate, and lower molecular weight of silicone oil.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.6
• /
• pp.1302-1307
• /
• 2006

This study describes the preparation of high-performance photocatalyst and its environmental applications. We prepared visible-light response nano-particle photocatalyst exhibiting the similar photocatalytic activity with $TiO_2$, dispersed $TiO_2$ on $SiO_2$ with an active rutile type titanium oxide prepared at low temperature. The binder and stable photocatalytic $TiO_2$ sol for photocatalytic system were also prepared. Such products were evaluated by UV/Vis spectrometer, X-ray diffraction analysis, SEM, measurement of photocatalytic activities and surface area, mechanical properties of $TiO_2$-coated surfaces. The results obtained can be applied in efficient photocatalytic systems using POF and metal plate for the purification of air.

• Applied Chemistry for Engineering
• /
• v.22 no.1
• /
• pp.21-25
• /
• 2011

In this study, anatase/brookite hybrid $TiO_2$ was prepared using different acid catalysts and microwave to improve photodegradation of organic pollutants. The methylene blue photodegradation properties of the prepared photocatalysts with different particle/crystal size and brookite fractions were investigated. Surface characteristics and particle sizes of anatase/brookite hybrid $TiO_2$ were evaluated using scanning electron microscopy (SEM) and laser diffraction particle size analyzer, respectively and crystal structures were investigated with X-ray diffraction (XRD). Methylene blue photodegradation properties were evaluated with UV-vis spectrophotometer. Anatase and anatase/brookite hybrid $TiO_2$ had less than 500 nm size of clusters and the average particle size of $6.66{\sim}6.85{\mu}m$, suggesting that types of acid catalysts did not affect the size. XRD of the prepared $TiO_2$ showed that the photocatalysts had anatase/brookite hybrid crystal structure and applying microwave did not change their crystal structure. Photodegradation of methylene blue with the prepared photocatalyst did not increased proportionally to the fraction of brookite and the crystal size and decreased when brookite fraction and the crystal size increased further. Anatase/brookite hybrid $TiO_2$ with brookite fraction of 9.4% and crystal size of 4.53 nm shows the best photodegradation activity of methylene blue.

• Korean Chemical Engineering Research
• /
• v.55 no.5
• /
• pp.718-722
• /
• 2017

We have investigated the photocatalytic activity for the decomposition of methyl orange on the pure $LaCoO_3$ and metal ion doped $LaCoO_3$ perovskite-typeoxides prepared using microwave process. In the case of pure $LaCoO_3$ and cesium ion doped $LaCoO_3$ catalysts, the formation of the perovskite crystalline phase was confirmed regardless of the preparation method. From the results of UV-Vis DRS, the pure $LaCoO_3$ and cesium ion doped $LaCoO_3$ catalysts have the similar absorption spectrum up to visible region. The chemisorbed oxygen plays an important role on the photocatalytic decomposition of methyl orange and the higher the contents of chemisorbed oxygen, the better performance of photocatalyst.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.816-819
• /
• 2007

국내에서 IGCC 플랜트의 복합발전시스템의 평가는 여러 분야별로 진행되어 왔다. 크게 살펴보면 다음과 같다. 첫 번째는 가스터빈 쪽의 기술이다. 즉, 기존 천연가스를 이용하는 가스터빈을 어떻게 하면 석탄가스를 사용하는 IGCC 플랜트에 적합하게 맞출 것인가 하는 문제이다. 두 번째는 효율을 어떻게 하면 높일 수 있는가의 문제로서 석탄의 종류, 가스화 방법을 효율적으로 선택, HRSG(heat recovery steam generator)를 효율적으로 설계, 그리고 정제공정에서의 에너지 소비를 줄이는 분야였다. 세 번째는 어떻게 하면 오염을 줄일까의 문제로서 질소나 스팀 분사를 연계하여 NOx를 감소시키고 정제 공정에 사용되는 촉매를 개발한다던지 공정을 발달시키는 분야였다. 이 외에도 여러 종류의 연구가 이 분야에서 있었으나 주로 설계 분야의 연구가 주되였다. 이것은 발전소의 건설을 위한 초기 단계로서 당연한 결과일 수 있다. 그러나, 지금 IGCC 플랜트가 건설되는 과정에 있으므로 우리나라 전력계통 연계와의 문제도 생각해보아야 한다고 생각한다. 따라서 이번 연구에서는 IGCC 플랜트 운영의 불확실성이 약간이라도 존재하기에 이 플랜트가 기저발전 보다는 첨두발전 쪽이나 태양열/광발전, 풍력발전 등 다른 신재생에너지 자원처럼 독립된 전력 시스템으로 운영될 것이라 생각하고 이렇게 운영될 때는 발전소의 부하률의 변화가 심할 수 있다는 가정하에 플랜트의 부하률에 따른 석탄의 합성가스, 연료가스 전환량 및 전환효율 및 발전량 및 발전효율을 전산모사를 통해 예측해보았다.

• Journal of Food Hygiene and Safety
• /
• v.19 no.2
• /
• pp.97-103
• /
• 2004

The present study was performed to investigate photodegradation rate constants and degradation products of piperophos by the USEPA method. The pesticide was very stable in 16 days exposure of sunlight from October 3 to 22, 2003 and humic acid had no sensitizing effect on the photolysis of each pesticide in sunlight. In the UV irradiation test, piperophos was rapidly degraded as increasing UV intensity. In case of UV irradiation with TiO$_2$ and with TiO$_2$ powder amount, degradation of piperophos was slower than UV irradiation. In order to identify photolysis product, the extracts of degradation product was analyzed by GC/MS. The mass spectrum of photolysis product of piperophos was at m/z 166. It was suggested that the photolysis products of piperophos was O, O-dipropyl phosphorodithioate.

• Journal of the Korean Chemical Society
• /
• v.17 no.2
• /
• pp.130-135
• /
• 1973

The rate-constants of hydrolysis of 3, 4-methylenedioxyphenylmethylenemalononitrile are determined by ultraviolet spectrophotometry at various pH and a rate equation which can be applied over wide pH range is obtained. The rate equation reveals that below pH 5.0 and above pH 9.0, the hydrolysis is initiated by the addition of water and hydroxide ion respectively. However, at pH 6.0-8.0 the competitive addition of water and hydroxide ion occurs. The catalytic contribution of hydroxide ion and water can be fully explained by the rate equation obtained.