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  • Title/Summary/Keyword: temperature programmed reaction

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Study on the Fuel Decomposition Characteristics and Coke Formation by Type of Endothermic Fuel and Method of Catalyst Molding (흡열연료 종류와 촉매 성형 방법에 따른 분해특성과 코크 생성에 관한 연구)

  • Lee, Tae Ho;Kang, Saetbyeol;Kim, Sung Hyun
    • Korean Chemical Engineering Research
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    • v.57 no.5
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    • pp.611-619
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    • 2019
  • This study was carried out to investigate fuel decomposition characteristics and coke formation according to types of endothermic fuels and methods of catalyst molding. Methylcyclohexane (MCH), n-dodecane, and exo-tetrahydrodipentadiene (exo-THDCP) were used as the endothermic fuels. As a catalyst, USY720 supported with platinum was used. It was manufactured by only using pressure to disk-type, or pelletized with a binder and a silica solution. The characteristics of the catalysts according to the molding method were analyzed by X-ray diffraction analysis, scanning electron microscopy, nitrogen adsorption-desorption isotherm, and ammonia temperature programmed desorption analysis. The reaction was carried out under conditions of high temperature and high pressure (500C, 50 bar) in which the fuel could exist in a supercritical state. The product was analyzed by gas chromatograph/mass spectrometer and the coke produced by the catalyst was analyzed by thermogravimetric analyzer. After the reaction, the composition of the products varied greatly depending on the structure of the fuel. In addition, the crystallinity and surface properties of the catalysts were not changed by the method of catalyst molding, but the changes of the acid sites and the pore characteristics were observed, which resulted in changes in the amount and composition of products and coke.

Catalytic Effects and Characteristics of Ni-based Catalysts Supported on TiO2-SiO2 Xerogel

  • Jeong, Jong-Woo;Park, Jong-Hui;Choi, Sung-Woo;Lee, Kyung-Hee;Lee, Chang-Seop
    • Bulletin of the Korean Chemical Society
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    • v.28 no.12
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    • pp.2288-2292
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    • 2007
  • The catalytic activities of nickel-based catalysts were estimated for oxidizing acetaldehyde of VOCs exhausted from industrial facilities. The catalysts were prepared by sol-gel methods of SiO2 and SiO2-TiO2 as a xerogel followed by impregnating Al2O3 powder with the nickel nitrate precursor. The crystalline structure and catalytic properties for the catalysts were investigated by use of BET surface area, X-ray diffraction (XRD), Xray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR) techniques. These results show that nickel oxide is transformed to NiAl2O4 spinel structure at the calcination temperature of 400 °C in response to the steps with after- and co-impregnation of Al2O3 powder in sol-gel process. The NiAl2O4 could suppress the oxidation reaction of acetaldehyde by catalysts. The NiO is better dispersed on SiO2-TiO2/Al2O3 support than SiO2/Al2O3 and SiO2-TiO2-Al2O3 supports. From the testing results of catalytic activities for oxidation of acetaldehyde, Catalysts showed a big difference in conversion efficiencies with the way of the preparation of catalysts and the loading weight of nickel. The catalyst of 8 wt.% Ni/TiO2-SiO2/Al2O3 showed the best conversion efficiency on acetaldehyde oxidation with 100% conversion efficiency at 350 °C.

Hydrogen Reduction Behavior and Microstructure Characteristics of Ball-milled CuO-Co3O4 Powder Mixtures (볼 밀링한 CuO-Co3O4 혼합분말의 수소환원 거동과 미세조직 특성)

  • Han, Ju-Yeon;Lee, Gyuhwi;Kang, Hyunji;Oh, Sung-Tag
    • Journal of Powder Materials
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    • v.26 no.5
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    • pp.410-414
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    • 2019
  • The hydrogen reduction behavior of the CuOSCo3O4 powder mixture for the synthesis of the homogeneous Cu-15at%Co composite powder has been investigated. The composite powder is prepared by ball milling the oxide powders, followed by a hydrogen reduction process. The reduction behavior of the ball-milled powder mixture is analyzed by X-ray diffraction (XRD) and temperature-programmed reduction at different heating rates in an Ar-10%H2 atmosphere. The scanning electron microscopy and XRD results reveal that the hydrogen-reduced powder mixture is composed of fine agglomerates of nanosized Cu and Co particles. The hydrogen reduction kinetics is studied by determining the degree of peak shift as a function of the heating rate. The activation energies for the reduction of the oxide powders estimated from the slopes of the Kissinger plots are 58.1 kJ/mol and 65.8 kJ/mol, depending on the reduction reaction: CuO to Cu and SCo3O4 to Co, respectively. The measured temperature and activation energy for the reduction of SCo3O4 are explained on the basis of the effect of pre-reduced Cu particles.

CO Oxidation Over Pt Supported on Al-Ce Mixed Oxide Catalysts with Different Mole Ratios of Al/(Al+Ce) (서로 다른 몰비의 Al/(Al+Ce)를 가진 Al-Ce 혼합산화물에 담지된 Pt 촉매 상에서의 일산화탄소 산화반응)

  • Park, Jung-Hyun;Cho, Kyung-Ho;Kim, Yun-Jung;Shin, Chae-Ho
    • Clean Technology
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    • v.17 no.2
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    • pp.166-174
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    • 2011
  • The xAl-yCe oxide catalysts with different mol ratios of Al/(Al+Ce) were prepared by a co-precipitation method and Pt supported on xAl-yCe oxide catalysts were synthesized by an incipient wetness impregnation method. The catalysts were characterized by X-ray Diffraction (XRD), N2 sorption, and H2/CO-temperature programmed reduction (H2/CO-TPR) to correlate with catalytic activities in co oxidation. Among the catalysts studied here, Pt/1Al-9Ce oxide catalyst showed the highest activity in dry and wet reaction conditions and the catalytic activity showed a typical volcano-shape curve with respect to Al/(Al+Ce) mol ratio. When the presence of 5% water vapor in the feed, the temperature of T_{50%} was shifted ca. 30C to lower temperature region than that in dry condition. From CO-TPR, the desorption peak of CO2 on Pt/1Al-9Ce oxide catalyst showed the highest value and well correlated the catalytic performance. It indicates that the Pt/1Al-9Ce oxide catalyst has a large amount of active sites which can be adsorbed by co and easy to supplies the needed oxygen. In addition, the amount of pentacoordinated Al3+ sites obtained through 27Al NMR analysis is well correlated the catalytic performance.

Synthesis of Mesoporous SAPO-34 Catalyst Using Chitosan and Its DTO Reaction (키토산을 이용한 메조 세공 SAPO-34 촉매의 합성 및 DTO 반응)

  • Yoon, Young-Chan;Song, Kang;Lim, Jeong-Hyeon;Park, Chu-Sik;Kim, Young-Ho
    • Applied Chemistry for Engineering
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    • v.32 no.3
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    • pp.305-311
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    • 2021
  • Effects of chitosan as a mesopore directing agent of SAPO-34 catalysts were investigated to improve the catalytic lifetime in DTO reaction. The synthesized catalysts were characterized by XRD, SEM, N2 adsorption-desorption isotherm and NH3-temperature programmed desorption (TPD). The modified SAPO-34 catalysts prepared by varying the added amount of chitosan showed the same cubic morphology and chabazite structure as the conventional SAPO-34 catalyst. As the added amount of chitosan increased to 3 wt%, the surface area, mesopore volume and concentration of weak acid sites of modified SAPO-34 catalysts increased. The modified SAPO-34 catalysts showed enhanced catalytic lifetime and high selectivity for light olefins in the DTO reaction. In particular, the SAPO-CHI 3 catalyst (3 wt%) exhibited the longest catalytic lifetime than that of the conventional SAPO-34. Therefore, it was confirmed that chitosan was a suitable material as a mesopore directing agent to delay deactivation of the SAPO-34 catalyst.

A study of hydrocarbon SCR(selective catalytic reduction) on Ag/γ-Al2O3 catalyst (Ag/γ-Al2O3 촉매상에서 탄화수소-SCR(Selective Catalytic Reduction) 연구)

  • Kim, Moon-Chan;Lee, Cheal-Gyu
    • Analytical Science and Technology
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    • v.18 no.2
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    • pp.139-146
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    • 2005
  • Removal of NO contained in automobile exhaust gas was accomplished by the non-selective catalyst reduction method. The catalysts were prepared through loading of a specific amount of Ag into γAl2O3. The conversion of NOx was studied by varying the temperatures, O2 concentrations and SO2 concentrations for the prepared catalysts. The influence of the structure of catalyst to NOx conversion was followed through the analysis of the physical properties of the prepared catalysts. Experiments were conducted on each of the catalysts by varying the reaction conditions to find an optimum condition. The catalyst Ag/γAl2O3 shows a highest NOx conversion when the Ag content was 2 wt% and a reaction temperature of about 450C. and after conducting the experiments, samples of before and after experiments analyzed using XRD, XPS, TPR, and UV-Vis DRS experiments. The result indicated that when Ag oxide content could not be maintained well at high temperatures NOx conversion decreased.

Oxidative Dehydrogenation of n-Butenes over BiFe0.65MoP0.1 Oxide Catalysts Prepared with Various Synthesis Method (다양한 합성 방법으로 제조된 BiFe0.65MoP0.1 산화물 촉매 상에서 n-부텐의 산화탈수소화 반응)

  • Park, Jung-Hyun;Shin, Chae-Ho
    • Korean Chemical Engineering Research
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    • v.53 no.3
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    • pp.391-396
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    • 2015
  • To investigate the effect of the catalyst synthesis method on the oxidative dehydrogenation (ODH) of nbutenes, BiFe0.65MoP0.1 oxide catalysts were prepared with various synthesis methods such as co-precipitation, citric acid method, hydrothermal method, and surfactant templated method. The catalysts were characterized by X-ray Diffraction (XRD), N2 sorption, and NH3/1-butene-temperature programmed desorption (NH3/1-butene-TPD) to correlate with catalytic activity in ODH reaction. Among the catalysts studied here, BiFe0.65MoP0.1 oxide catalyst prepared with co-precipitation method marked the highest activity showing 1-butene conversion, 79.5%, butadiene selectivity, 85.1% and yield, 67.7% after reaction for 14 h. From the result of NH3-TPD, the catalytic activity is closely related to the acidity of the BiFe0.65MoP0.1-x oxide catalyst and acidity of the BiFe0.65MoP0.1 oxde catalyst prepared with co-precipitation method was higher than that of other catalysts. In addition, combined with the 1-butene TPD, the higher catalytic activity is closely related to the amount of weakly adsorbed intermediate (< 200C) and the desorbing temperature of strongly adsorbed intermediates (> 200C).

CO2 Decomposition Characteristics of Zn-ferrite Powder Prepared by Hydrothermal and Solid State Reaction (수열합성법과 고상법을 이용해 제조된 Zn-ferrite 분말의 이산화탄소 분해 특성)

  • Nam, Sung Chan;Park, Sung Youl;Yoon, Yeo Il;Jeong, Soon Kwan
    • Applied Chemistry for Engineering
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    • v.22 no.5
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    • pp.555-561
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    • 2011
  • The objective of this study is the development of carbon recycle technology which converts CO2 captured from flue gas to CO or carbon and reuse in industrial fields. Since CO2 is very stable and difficult to decompose, metal oxide was used as an activation agent for the decomposition of CO2 at low temperature. Metal oxides which convert CO2 to CO or carbon at 500C were prepared using Zn-ferrite by the solid state reaction and hydrothermal synthesis. The behaviors of CO2 decomposition were studied using temperature programmed reduction/oxidation (TPR/TPO) and thermogravimetric analyzer (TGA). Zn-ferrite containing 5 wt% ZnO showed the largest reduction and oxidation. Reduction by H2 was 26.53 wt%, oxidation by CO2 was 25.73 wt% and 96.98% of adsorbed CO2 was decomposed to CO2 and carbon with excellent oxidation-reduction behaviors.

Effect of Metal Addition and Silica/Alumina Ratio of Zeolite on the Ethanol-to-Aromatics by Using Metal Supported ZSM-5 Catalyst (금속담지 ZSM-5 촉매를 사용한 에탄올로부터 방향족 화합물 제조에 관한 제올라이트의 금속성분 및 실리카/알루미나 비의 영향)

  • Kim, Han-Gyu;Yang, Yoon-Cheol;Jeong, Kwang-Eun;Kim, Tae-Wan;Jeong, Soon-Yong;Kim, Chul-Ung;Jhung, Sung Hwa;Lee, Kwan-Young
    • Korean Chemical Engineering Research
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    • v.51 no.4
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    • pp.418-425
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    • 2013
  • The catalytic conversion of ethanol to aromatic compounds ETA was studied over ZSM-5 heterogeneous catalysts. The effect of reaction temperature, weight hourly space velocity (WHSV), and addition of water and methanol, which are the potential impurities of bio-ethanol, on the catalytic performance was investigated in a fixed bed reactor. Commercial ZSM-5 catalysts having different Si/Al2 ratios of 23 to 280 and modified ZSM-5 catalysts by addition of metal (Zn, La, Cu, and Ga) were used for the activity and stability tests in ETA reaction. The catalysts were characterized with ammonia temperature programmed desorption (NH3-TPD) and nitrogen adsorption-desorption techniques. The results of catalytic performance revealed that the optimal Si/Al2 ratio of ZSM-5 is about 50~80 and the selectivity to aromatic compounds decreases in the order of Zn/La > Zn > La > Cu > Ga for the modified ZSM-5 catalysts. Among these catalysts from the ETA reaction, Zn-La/ZSM-5 showed the best catalytic performance for the ETA reaction. The selectivity to aromatic compounds was 72% initially and 56% after 30 h over the catalysts at reaction temperature of 437C and WHSV of 0.8h1.

Synthesis and Characterization of High Surface Area of Zirconia: Effect of pH (고비표면적 지르코니움 산화물의 제조 및 특성 분석: pH 영향)

  • Jeong, Ye-Seul;Shin, Chae-Ho
    • Korean Chemical Engineering Research
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    • v.57 no.1
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    • pp.133-141
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    • 2019
  • High specific surface area zirconia with acid-basic property was synthesized by precipitation using reflux method or hydrothermal synthesis method using ammonium hydroxide solution as precipitant in the range of pH of Zr solution from 2 to 10. The prepared zirconia was characterized by the nitrogen adsorption, X-ray diffraction (XRD), isopropanol temperature programmed desorption (IPA-TPD), scanning electron microscopy and X-ray photoelectron spectroscopy, and the catalytic activity in the IPA decomposition reaction was correlated with the acid-basic properties. When using reflux method, high pH of Zr solution was required to obtain high fraction of tetragonal zirconia, and pure tetragonal zirconia was possible at pH 9 or higher. High pH was required to obtain high specific surface area zirconia, and the hydrous zirconia synthesized at pH 10 had high specific surface area zirconia of 260m2g1 even after calcination at 600C. However, hydrothermal synthesis with high pressure under the same conditions resulted in very low specific surface area below 40m2g1 and monoclinic phase zirconia was synthesized. High pH of the solution was required to obtain high specific surface area tetragonal phase zirconia. In hydrothermal synthesis requiring high pressure, monoclinic zirconia was produced irrespective of the pH of the solution, and the specific surface area was relatively low. Zirconia with high specific surface area and tetragonal phase was predominantly acidic compared to basicity and only propylene, which was observed as selective dehydration reaction in IPA decomposition reaction, was produced.