• Title, Summary, Keyword: Catalytic chemical reaction

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Homogeneous and Catalytic Methanol Synthesis by Partial Oxidation of Methane (메탄의 균일 및 접촉부분산화에 의한 메탄올 합성)

  • Hahm, Hyun-Sik;Choi, Woo-Jin;Hwang, Jae-Young;Ahn, Sung-Hwan;Kim, Myung-Soo;Park, Hong-Soo
    • Journal of the Korean Applied Science and Technology
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    • v.22 no.1
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    • pp.56-61
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    • 2005
  • Methanol was synthesized by homogeneous and catalytic reactions of partial oxidation of methane. The effect of pressure, temperature and oxygen concentration on methanol synthesis was investigated. The catalyst used was Bi-Cs-Mg-Cu-Mo mixed oxide. The partial oxidation reaction was carried out in a fixed bed reactor at 20${\sim}$46 bar and $450{\sim}480^{\circ}C$ and oxygen concentration of 5.3${\sim}$7.7mol%. The results were compared with results of homogeneous reaction performed at the same conditions. Methane conversions of the homogeneous and catalytic reactions increased with temperature. Methanol selectivity of the homogeneous reaction decreased with increasing temperature. However, the methanol selectivity of catalytic reaction increased with temperature. For both homogeneous and catalytic reactions, the methane conversions were around 5%. This may be due to the low oxygen concentration. Methanol selectivity of the catalytic reaction was higher than that of homogeneous one.

A study on the direct catalytic steam gasification of coal for the bench-scale system

  • Kang, Tae-Jin;Park, HyeJung;Namkung, Hueon;Xu, Li-Hua;Park, Jung-Hyun;Heo, Iljeong;Chang, Tae-Sun;Kim, Beom Sik;Kim, Hyung-Taek
    • The Korean Journal of Chemical Engineering
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    • v.34 no.10
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    • pp.2597-2609
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    • 2017
  • Various techniques have been developed to increase the efficiency of coal gasification. The use of a catalyst in the catalytic-steam gasification process lowers the activation energy required for the coal gasification reaction. Catalytic-steam gasification uses steam rather than oxygen as the oxidant and can lead to an increased $H_2/CO$ ratio. The purpose of this study was to evaluate the composition of syngas produced under various reaction conditions and the effects of these conditions on the catalyst performance in the gasification reaction. Simultaneous evaluation of the kinetic parameters was undertaken through a lab-scale experiment using Indonesian low rank coals and a bench-scale catalytic-steam gasifier design. The composition of the syngas and the reaction characteristics obtained in the lab- and bench-scale experiments employing the catalytic gasification reactor were compared. The optimal conditions for syngas production were empirically derived using lab-scale catalytic-steam gasification. Scale-up of a bench-scale catalytic-steam gasifier was based on the lab-scale results based on the similarities between the two systems. The results indicated that when the catalytic-steam gasification reaction was optimized by applying the $K_2CO_3$ catalyst to low rank coal, a higher hydrogen yield could be produced compared to the conventional gasification process, even at low temperature.

Optimization by Simulated Catalytic Reaction: Application to Graph Bisection

  • Kim, Yong-Hyuk;Kang, Seok-Joong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.5
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    • pp.2162-2176
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    • 2018
  • Chemical reactions have an intricate relationship with the search for better-quality neighborhood solutions to optimization problems. A catalytic reaction for chemical reactions provides a clue and a framework to solve complicated optimization problems. The application of a catalytic reaction reveals new information hidden in the optimization problem and provides a non-intuitive perspective. This paper proposes a new simulated catalytic reaction method for search in optimization problems. In the experiments using this method, significantly improved results are obtained in almost all graphs tested by applying to a graph bisection problem, which is a representative problem of combinatorial optimization problems.

Syntheses and Phase-transfer Catalytic Activities of Monoazacrown Ethers

  • Shim Jae Hu;Chung Kwang Bo;Masao Tomoi
    • Bulletin of the Korean Chemical Society
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    • v.13 no.3
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    • pp.252-255
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    • 1992
  • Preparative methods for and catalytic activities of monoaza-18-crown-6 or monoaza-15-crown-5 in the reaction of 1-bromooctane with aqueous KI or NaI were investigated. Monoazacrown ethers were prepared by debenzylation of N-benzylmonoazacrown ethers, obtained from the reaction of N-benzyldiethanolamine and oligoethylene glycol ditosylate. The phase-transfer catalytic activity of N-benzylmonoazacrown ethers was higher than that of the corresponding monoazacrown ethers.

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Temperature-dependent studies on catalytic hydrosilation of polyalkylsiloxane using NMR

  • Sul, Hyewon;Lee, Tae Hee;Lim, Eunsoo;Rho, Yecheol;Kim, Chong-Hyeak;Kim, Jeongkwon
    • Analytical Science and Technology
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    • v.30 no.4
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    • pp.213-219
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    • 2017
  • Polyalkylsiloxane has been spotlighted in pressure-sensitive adhesive (PSA) application due to excellent physical properties and good biocompatibility. Thermal behaviour of polyalkylsiloxane mixtures, such as thermal stability and heat flow, were studied using TG-DTA during catalytic hydrosilation. To understand reaction kinetics of cross-linking, catalytic hydrosilation of polyalkylsiloxane was monitored using variable temperature nuclear magnetic resonance (VT-NMR) as increased temperature. The formation of cross-linking bond $Si-CH_2-CH_2-Si$ was directly observed using distortionless enhanced by polarization transfer (DEPT) technique. Successfully polyalkylsiloxane PSA samples exhibited excellent adhesion properties by cross-linking reaction.

Catalytic Combustion of Methane over Perovskite-Type Oxides

  • Hong, Seong-Soo;Sun, Chang-Bong;Lee, Gun-Dae;Ju, Chang-Sik;Lee, Min-Gyu
    • Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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    • v.4 no.2
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    • pp.95-102
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    • 2000
  • Methane combustion over perovskite-type oxides prepared using the malic acid method was investigated. To enhance the catalytic activity, the perovskite oxides were modified by the substitution of metal into their A or B site. In addition, the reaction conditions, such as the temperature, space velocity, and partial pressure of the methane were varied to understand their effect on the catalytic performance. With the LaCoO3-type catalyst, the partial substitution of Sr or Ba into site A enhanced the catalytic activity in the methane combustion. With the LaBO3(B=Co, Fe, Mn, Cu)-type catalyst, the catalytic activities were exhibited in the order of Co>Fe Mn>Cu. Futhermore, the partial substitution of Co into site B enhanced the catalytic activity, whereas an excess amount of Co decreased the activity. The surface area and catalytic activity of the perovskite catalysts prepared using the malic acid method showed higher values than those prepared using the solid reaction method. The catalytic activity was enhanced with decreased methane concentration and with a decrease in the space velocity.

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TMEDA Catalyzed Henry (Nitroaldol) Reaction under Metal and Solvent-free Conditions

  • Majhi, Anjoy;Kadam, Santosh T.;Kim, Sung-Soo
    • Bulletin of the Korean Chemical Society
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    • v.30 no.8
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    • pp.1767-1770
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    • 2009
  • The Henry (nitroaldol) reaction proceeds under mild conditions with catalytic amount of tetramethylethylenediamine (TMEDA) to afford $\beta$-nitro alkanol in considerably excellent yield. Structurally diverse aldehydes react with nitromethane in presence of 0.3 equiv of TMEDA under solvent-free condition at rt. The low catalytic loading and mild reaction condition are the key features of the catalytic method.

A Study on the Improvement of Decomposition Efficiency of Organic Substances Using Plasma Process and Catalytic Surface Chemical Reaction (플라즈마 프로세스 및 촉매 표면화학반응에 의한 유기화합물 분해효율 향상에 대한 연구)

  • Han, Sang-Bo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.5
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    • pp.932-938
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    • 2010
  • This paper proposed the effective treatment method for organic substances using the barrier discharge plasma process and catalytic chemical reaction followed from ozone decomposition. The decomposition by the plasma process of organic substances such as trichloroethylene, methyl alcohol, acetone, and dichloromethane carried out, and ozone is generated effectively at the same time. By passing through catalysts, ozone easily decomposed and further decomposed organic substances. And, 2-dimensional distribution of ozone using the optical measurement method is performed to identify the catalytic surface chemical reaction. In addition, CO is easily oxidized into $CO_2$ by this chemical reaction, which might be induced oxygen atom radicals formed at the surface of catalyst from ozone decomposition.

Catalytic Oxidation of Trichloroethylene over Pd-Loaded Sulfated Zirconia

  • Park, Jung-Nam;Lee, Chul-Wee;Chang, Jong-San;Park, Sang-Eon;Shin, Chae-Ho
    • Bulletin of the Korean Chemical Society
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    • v.25 no.9
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    • pp.1355-1360
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    • 2004
  • The oxidative decomposition of trichloroethylene (TCE) was investigated using palladium catalysts supported on pure and sulfated zirconia. The reactions were performed under dry and wet conditions in the temperature between 200 and $550^{\circ}C$ keeping GHSV of 14,000 $h^{-1}.$ The products such as $C_2Cl_4,\;C_2HCl_5,\;CO\;and\;CO_2$ were observed in the reaction. The addition of water in the feed affected the distribution of reaction product with dramatically improved catalytic activity. The spectroscopic investigations gave an evidence that the strong acid sites play an important role on controlling the catalytic activity. Among the catalysts investigated, the Pd-loaded sulfated zirconia catalyst with 1 wt% Pd was found to exhibit the highest catalytic activity in the presence of water vapor having the stability for 30 h of the reaction at $500^{\circ}C$. The successful performance of the catalyst might be attributed to promotional effect of Pd active sites and strong acid sites induced from surface sulfate species on zirconia.

Facile Preparation of ZnO Nanocatalysts for Ozonation of Phenol and Effects of Calcination Temperatures

  • Dong, Yuming;Zhao, Hui;Wang, Zhiliang;Wang, Guangli;He, Aizhen;Jiang, Pingping
    • Bulletin of the Korean Chemical Society
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    • v.33 no.1
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    • pp.215-220
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    • 2012
  • ZnO nanoparticles were synthesized through a facile route and were used as ozonation catalysts. With the increase of calcination temperature ($150-300^{\circ}C$), surface hydroxyl groups and catalytic efficiency of asobtained ZnO decreased remarkably, and the ZnO obtained at $150^{\circ}C$ showed the best catalytic activity. Compared with ozonation alone, the degradation efficiency of phenol increased above 50% due to the catalysis of ZnO-150. In the reaction temperatures range from $5^{\circ}C$ to $35^{\circ}C$, ZnO nanocatalyst revealed remarkable catalytic properties, and the catalytic effect of ZnO was better at lower temperature. Through the effect of tertbutanol on degradation of phenol and the catalytic properties of ZnO on degradation of nitrobenzene, it was proposed that the degradation of phenol was ascribed to the direct oxidation by ozone molecules based on solidliquid interface reaction.