• Title/Summary/Keyword: Catalytic Effect

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Improvement of DeNOx efficiency of SNCR Process with Chemical Additives in Urea Soution (환원제로 우레아를 사용하는 SNCR 공정에서 첨가제 적용에 따른 탈질효율 향상 연구)

  • Yoo, Kyung Seun;Park, Sung Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.663-668
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    • 2017
  • Dye waste water generated in the dye industry is categorized as hazardous waste water that requires appropriate treatment. The pilot scale experimental trials were carried out using dye waste water as an effective additive for the selective non-catalytic reduction (SNCR) of NOx in combustion flue gases. The additives were waste liquor obtained from the dye industry and several purification steps were taken to make a standardized reagents. The dye waste water was shown to possess valuable SNCR qualities (at least 87% NOx reduction efficiency) considering its availability as a waste product, which has to be strictly treated, and have little effects on CO removal. The results indicated that the NO removal efficiency increased first and then decreased with increasing temperature within $750-1150^{\circ}C$. The maximum NO reduction efficiency was approximately 87% at the optimal reaction temperature. A more than 10% increase in NO reduction was achieved in the presence of 1000 ppm Na-additives (dye waste water) compared to that without additives. The Na-based additives have also a significant promoting effect on $N_2O$ reduction and within the SNCR temperature window.

DNA-Independent ATPase Activity of Deinococcus radiodurans RecA Protein Is Activated by High Salt (고농도 염에 의한 Deinococcus radiodurans RecA 단백질의 DNA 비의존성 ATPase 역가의 활성화)

  • Kim, Jong-Il
    • Korean Journal of Microbiology
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    • v.46 no.4
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    • pp.313-318
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    • 2010
  • Deinococcus radiodurans RecA protein, when bound to DNA, exhibits a DNA-dependent ATPase. In the absence of DNA, the rate of RecA protein-promoted ATP hydrolysis drops 1,000-fold under the physiological concentrations of salt. This DNA-independent activity can be stimulated to levels approximating those observed with DNA by adding high concentrations (approximately 1.6 M) of a wide variety of salts. This effect was characterized by varying salt concentration and comparing the effects of different ion types. The higher concentrations of salt stimulated the ATP hydrolysis by RecA protein in the absence of DNA. At 1.6 M chloride, the observed stimulation showed the following cation trend $K^+{\geq}Na^+$ > $NH_4^+$ and the following anion sequence was observed: $glutamate^- \; > \; C1^- \;> \; acetate^-\; > \;PO_4^-$ at 1.6 M $K^+$. The catalytic properties of the salt-stimulated ATP hydrolysis reaction was optimal between pH 7.0 and 8.0, which was similar to the double stran nded DNA-dependent ATPase activities of Deinococcus radiodurans RecA protein. In the absence of DNA the active species for ATP hydrolysis by RecA protein was shown to be an aggregate of three RecA protein molecules.

Influence of Ni/CeO2-ZrO2 Catalysts on Methane Autothermal Reforming (메탄 자열개질 반응에 대한 Ni/CeO2-ZrO2 촉매의 영향)

  • Kang, Min Goo;Lee, Tae Jun;Lee, Jong Dae
    • Korean Chemical Engineering Research
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    • v.47 no.1
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    • pp.17-23
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    • 2009
  • The catalytic behavior of $Ni/Ce_XZr_{(1-X)}O_2$ loaded on the alumina coated honeycomb monolith was studied for the autothermal reforming reaction of methane. Among the catalysts with the different Ce/Zr ratios, the $Ni/Ce_{0.80}Zr_{0.20}O_2$ Catalyst showed the highest conversion of methane. By investigating the effect of Ni content on the $Ni/Ce_{0.80}Zr_{0.20}O_2$ catalysts, the catalyst loaded with 15wt% Ni had the highest activity. Also, $H_2$ yield was increased as $H_2O/CH_4$ ratio increased. Methane conversion was improved as $O_2/CH_4$ ratio was increased, whereas the yield of $H_2$ was decreased. Among the catalysts tested for 30 hours, $Ni(15wt%)/Ce_{0.80}Zr_{0.20}O_2$ showed the excellent conversion(${\geq}99%$) of methane and the stability at the condition of $GHSV=30,000h^{-1}$, feed ratio S/C/O=2/1/0.5 and reaction temperature $800^{\circ}C$.

Studies on Electroanalytical Chemistry for the Oxygen Adducted Tetradentate Schiff base Cobalt(III) Complexes in Pyridine Solution (Pyridine 용액에서 산소 첨가된 네자리 Schiff base Cobalt(III) 착물들의 전기 분석화학적 연구)

  • Rim, Chae-Pyeong;Chae, Hee-Nam;Chjo, Ki-Hyung;Choi, Yong-Kook
    • Analytical Science and Technology
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    • v.8 no.1
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    • pp.55-62
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    • 1995
  • Tetradentate Schiff base cobalt(II) complexes such as $Co(II)_2-N$, N-bis(salicylidene)-m-phenylendiimine; [$Co(II)_2(SMPD)_2(H_2O)_4$] and $Co(II)_2-N$, N-bis(salicylidene)-p-phenylendiimine: [$Co(II)_2(SPPD)_2(H_2O)_4$], and oxygen adducted cobalt (III) complexes such as [$Co(III)_2O_2(SMPD)_2(Py)_2$] and [$Co(III)_2O_2(SPPD)_2(Py)_2$] in pyridine solutions were synthesized. It was identified that the oxygen adducted cobalt(III) complexes have hexacoordinated octahedral configuration with pyridine and oxygen from the measurement of elemental analysis, AA, IR spectra, and TGA. The redox processes were investigated for the oxygen adducted complexes in 0.1M TEAP-pyridine solution, using cyclic voltammetry on the glassy carbon electrode. The redox processes of oxygen adducted Co(III) complexes result in $$[Co(III)_2-O_2-CO(III)]\rightarrow^{e^-}[Co(III)-O_2-Co(II)]\rightarrow^{e^-}[Co(II)-O_2-Co(II)]\rightleftarrows^{e^-}[Co(II)+Co(II)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(II)+Co(I)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(I)+Co(I)+O_2{\cdot}^-]$$.

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The Effects of SO2 and NH3 on the N2O Reduction with CO over MMO Catalyst (MMO 촉매와 CO 환원제에 의한 N2O 분해에서 SO2 및 NH3 영향 연구)

  • Chang, Kil Sang;You, Kyung-Chang
    • 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.

The Catalytic Reduction of Sulfur Dioxide to Elemental Sulfur over Supported Cobalt Catalysts (담지 코발트 촉매를 이용한 SO2의 원소황으로의 환원반응 특성)

  • Park, Joon Hyo;Han, Jong Dae
    • Applied Chemistry for Engineering
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    • v.10 no.8
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    • pp.1129-1135
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    • 1999
  • The reduction of $SO_2$ by CO over supported cobalt catalysts was investigated within the temperature range of $350{\sim}550^{\circ}C$, initial $SO_2$ concentration of 1000~10000 ppm, $CO/SO_2$ molar ratio of 1.0~3.0 and space velocity of $5000{\sim}15000h^{-1}$. Several types of supports such as ${\gamma}-Al_2O_3$, $TiO_2$ were tested. The $SO_2$ conversion and selectivity to elemental sulfur were investigated using a differential fixed bed reactor at atmospheric pressure. The catalyst prepared by wet impregration of 5 wt % cobalt on ${\gamma}-Al_2O_3$ showed $SO_2$ conversion higher than 90% and COS yield lower than 6% at temperature above $400^{\circ}C$. The optimum $CO/SO_2$ molar ratio was investigated as 2.0. At higher $CO/SO_2$ molar ratio, the $SO_2$ conversion became higher but the main product was COS. The effect of $SO_2$ concentration and space velocity over $SO_2$ conversion and COS yield was not appreciable in the experimental range. The activated cobalt phase was detected as $CoS_2$ and the $CoS_2$ phase unchanged even after reaction.

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The Effect of Crystal Size of SAPO-34 Synthesized Using Various Structure Directing Agents for MTO Reaction (다양한 구조 유도제로써 합성된 SAPO-34의 결정크기가 메탄올로부터 올레핀 전환반응(MTO)에 미치는 영향)

  • Song, Young-Ha;Chae, Ho-Jeong;Jeong, Kwang-Eun;Kim, Chul-Ung;Shin, Chae-Ho;Jeong, Soon-Yong
    • Applied Chemistry for Engineering
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    • v.19 no.5
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    • pp.559-567
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    • 2008
  • SAPO-34 is a well-known catalyst for methanol to olefins (MTO) process, but is rapidly deactivated by coke formation. It is necessary to improve the catalyst lifetime of SAPO-34 for MTO process. In the present work, SAPO-34 catalysts were synthesized with a variety of structure directing agent, and the physicochemical properties of the catalysts were examined by $N_2$-isotherm, XRD, SEM, and $NH_3$-TPD. It was found that mixed structure directing agents, especially DEA and TEAOH, gave well developed SAPO-34 crystal structure and reduced the crystal size and moderated acidity of SAPO-34 under the same synthetic conditions as that of various structure directing agents. Also, we could find that SAPO-34 catalyst prepared by mixed templates of DEA and TEAOH had the superior catalytic activity and the longer lifetime in MTO reaction.

Expression of DNA-dependent Protein Kinase and Its Relationship with Epidermal Growth Factor Receptor Signaling in Metastatic Cancer Cell Lines (DNA-PK 및 표피성장인자수용체의 신호전달이 암전이에 미치는 영향)

  • Hwang Jee Young;Kim Sun Hee;Kang Chi Dug;Yoon Man Soo
    • Journal of Life Science
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    • v.15 no.3 s.70
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    • pp.406-414
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    • 2005
  • The genetic instability of cancer cells may be related to inappropriately activated DNA repair pathways. In present study, the modulated expression of DNA-dependent protein kinase (DNA-PK), a major DNA repair protein, in human cancer metastatic cells was tested. The expressions of Ku70/80, regulatory subunit of DNA-PK, and the Ku DNA-binding activity in various highly metastatic cell lines were higher than those in each parental cell line. Also, the expression of DNA-PKcs, catalytic subunit of DNA-PK, and the kinase activity of the whole DNA-PK complex in highly metastatic cells were significantly increased as compared to those of parental cells, suggesting that the enhanced DNA repair capacity of metastatic cells could be associated with aberrant use of DNA repair, which may mediate tumor progression and metastatic potential. Increased EGFR (epidermal growth factor receptor) signaling has been associated with tumor invasion and metastasis, and the linkage between EGFR-mediated signaling and DNA-PK has been suggested. This study showed that PKI166, the new EGFR tyrosine kinase inhibitor, modulated the expressions of Ku70/80 and DNA-PKcs and also revealed the chemosensitization effect of PKI166 against metastatic cells may be in part due to inhibition of Ku70/80. These results suggest that interference in EGFR signaling by EGFR inhibitor resulted in the impairment of DNA repair activity, and thus DNA-PK could be possible molecular targets for therapy against metastatic cancer cells.

A Development of Communication and Relationship Enrichment Program for Multicultural Couples (다문화가정 부부의 의사소통 및 관계 증진 프로그램 개발)

  • Kim, GumHee;Min, Ki-yeon;Lee, Youngsun
    • The Journal of the Korea Contents Association
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    • v.15 no.11
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    • pp.202-214
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    • 2015
  • This study aims to develop and apply communication and relationship enrichment programs for married multicultural couples and verify its effects. This preliminary program was developed based on results from reviews of existing intervention programs, participants' interview for their needs and professionals' feedback on program. The program includes 11 sessions(once a week; 2 hours per session) focusing on communication strategies and related activities using marital counseling. Four multicultural couples participated in the intervention program. Qualitative data was collected during the program, including voice recording files, activity sheets, and filed notes conducted by researchers. Based on the results from the data analysis, we could find the intervention program had an positive effect on the communication between multicultural couples. Specifically, the intervention program could (1) enhanced intimacy in the couples, (2) started conversation and improved communication patterns between the couples. And also (3) modes of communication were changed to more collaborative communication through this program. The marital communication program developed in this study is significant in that it played a catalytic role for marital conversation in multicultural couples and used professional counseling techniques and strategies in solving and managing marital conflict.

Selective Oxidation of Hydrogen Over Palladium Catalysts in the Presence of Carbon Monoxide: Effect of Supports (Pd 촉매상에서 일산화탄소 존재 하 수소의 선택적 산화반응: 담체 효과)

  • Kim, Eun-Jeong;Kang, Dong-Chang;Shin, Chae-Ho
    • Korean Chemical Engineering Research
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    • v.55 no.1
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    • pp.121-129
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    • 2017
  • Pd based catalysts were prepared by impregnating palladium precursor using incipient wetness method on $TiO_2$, $Al_2O_3$, $ZrO_2$, and $SiO_2$ and were applied for the selective oxidation of $H_2$ in the presence of CO. Their physicochemical properties were studied by X-ray diffraction (XRD), $N_2$-sorption, temperature programmed desorption of CO (CO-TPD) and (CO+$H_2O$)-TPD, temperature programmed reduction of CO (CO-TPR) and XPS a. The results of CO- and (CO+$H_2O$)-TPD showed the correlation between peak temperature of TPD and catalytic activities for $H_2$ and CO conversion. The $Pd/ZrO_2$ catalyst exhibited the highest conversion of $H_2$. The addition of $H_2O$ vapor promotes the conversion of $H_2$ and CO by inducing easy desorption of CO and $H_2$ in the competitive adsorption of $H_2O$, CO and $H_2$.