Min-Chul Chung

Structure, magnetic and ion-exchange properties of self-assembled triaza-copper(II)-oxalate hybrides having nanoscale one-dimensional channel.

The X-ray structure, porous and magnetic property of a self-assembled network 1 is described in detail. The single crystal X-ray analysis provides 1 as a three-dimensional network, which contains two-dimensional permanent ring forming nanoscale one-dimensional channels. The inter-replacement of perchlorate and hexafluorophosphate anions in solid 1 proves its porous structure. There is somewhat strong antiferromagnetic interaction (J = -74.1 cm(-1)) between two copper(II) ions through oxalate bridge and weak antiferromagnetic interaction (J = -5.1 cm(-1) through AEP ligand.

Adsorption-desorption characteristics of modified activated carbons for volatile organic compounds

Modification techniques for activated carbon were used to increase the removal capacity by surface adsorption and to improve the selectivity to volatile organic compounds (VOCs). Modified activated carbons (MACs) were prepared by modifying the purified activated carbon with various acids or bases. The effects of adsorption capacity and modified contents on the textural properties of the MACs were investigated. Furthermore, VOC adsorption and desorption experiments were carried out to determine the relationship between the adsorption capacity and the chemical properties of the adsorbents. High adsorption capacity for the selected VOCs was obtained over 1 wt%-H 3 PO 4 /AC (1wt%-PA/AC). As a result, MAC was found to be very effective for VOC removal by adsorption with the potential for repeated use through desorption by simple heat treatment.

Study on Conversion of Carbon Dioxide to Methyl Alcohol over Ceramic Monolith Supported CuO and ZnO Catalysts

Methyl alcohol is one of the basic intermediates in the chemical industry and is also being used as a fuel additive and as a clean burning fuel. In this study, conversion of carbon dioxide to methyl alcohol was investigated using catalytic chemical methods. Ceramic monoliths (M) with were used as catalyst supports. Monolith-supported CuO-ZnO catalysts were prepared by wash-coat method. The prepared catalysts were characterized by using ICP analysis, TEM images and XRD patterns. The catalytic activity for carbon dioxide hydrogenation to methyl alcohol was investigated using a flow-type reactor under various reaction temperature, pressure and contact time. In the preparation of monolith-supported CuO-ZnO catalysts by wash-coat method, proper concentration of precursors solution was 25.7% (w/v). The mixed crystal of CuO and ZnO was well supported on monolith. And it was known that more CuO component may be supported than ZnO component. Conversion of carbon dioxide was increased with increasing reaction temperature, but methyl alcohol selectivity was decreased. Optimum reaction temperature was about under 20 atm because of the reverse water gas shift reaction. Maximum yield of methyl alcohol over CuO-ZnO/M catalyst was 5.1 mol% at and 20 atm.

Preparation of Styrenated Phenol Over SO2−4/ZrO2 Catalyst in a Large-Scale Synthesis Process

Styrenated phenols (SPs) are usually synthesized by the reaction of styrene and phenol under acid catalysts. SPs with a high content of di-styrenated phenol (DSP) can be used to prepare styrenated phenol alkoxylate (SP-A). Therefore, in this study, a scale-up process for synthesizing SPs with high DSP content which can be used for synthesis of SP-A was studied. The solid catalyst used in this study was prepared by impregnation method. SO2-₄ was impregnated on a SO2-₄/ZrO₂ catalyst in an aqueous 1 M H₂SO₄ solution. The prepared catalysts were characterized by NH3-TPD. Catalytic activity was examined by measuring the conversion of phenol and styrene in a liquid-phase batch reactor. Almost 100% conversion of both phenol and styrene over 5-SO2-₄/ZrO₂ catalyst was obtained at a reaction temperature of 80 °C and a reaction time of 6 h. The amount of catalyst to the reactants was 2 wt%. Under the same reaction conditions, the selectivity of MSP, DSP, and TSP was 12.4%, 64.5%, and 23.1% respectively.

A Synthesis of Alkoxylates from Styrenated Phenols and Ethylene Carbonate Over KOH/La2O3 Catalysts

Styrenated phenol alkoxylates (SP-A) are prepared from styrenated phenols (SP) and ethylene oxide (EO) under a homogeneous base catalyst. However, to use EO that is difficult to handle, a high-pressure reaction device capable of reaction process control should be used. Additionally, the homogeneous base catalyst requires a neutralization process to remove the remaining catalyst after the reaction, and it is difficult to separate the catalysts and the product. Therefore, in this study, the separation of product and catalyst by using KOH/La₂O₃ catalyst was facilitated in the production of SP-A. Also, it was possible to produce SP-A under atmospheric pressure reaction conditions using EC. The mean molecular weight of SP-A varied depending on the reaction conditions, and the size of the mean molecular weight could be arbitrarily controlled by changing the reaction conditions.

A Study on H2SO4-Treated MxOy Catalysts for Styrenated Phenols by Alkylation of Phenol with Styrene

Styrenated phenols (SPs) involving very small amount of unreacted phenol and high content of di-SP (DSP) were synthesized, which can be used to prepare SP alkoxylate. The solid catalyst was prepared by impregnation method. SO2-4 on SO2-4/MxOy catalyst was introduced from an aqueous 1M-H2SO4 solution. The catalysts were characterized by XRD patterns, and FT-IR spectra. The catalytic activity was examined by measuring conversion of phenol and styrene in a batch liquid-phase reactor. The concentration of phenol, styrene, and SPs were measured by GC with capillary column. The optimum synthesis conditions for concentration of sulfuric acid solution, catalyst amount of reactants, reaction temperature, and reaction time over SO2-4/ZrO2 catalyst were 15 wt%, 15 wt%, 100 °C, and 6 hr, respectively. At these conditions, conversion of both phenol and styrene were almost 100%, and the selectivity of DSP was 52.1%. On the other hand, the optimum synthesis conditions over SO2-4/TiO2 catalyst were 10 wt%, 5 wt%, 100 °C, and 1 hr, respectively, and conversion of both phenol and styrene were almost 100%, and the selectivity of DSP was 66.1%.

A Study on Synthesis of Styrenated Phenol Over Al · Ni/SiO2-Supported Catalysts

Styrenated phenol was prepared by an alkylation of phenol using NiCl2 and AlCl3 supported on silica gel. The conversion of phenol and styrene of alkylation reaction, and the selectivity of styrenated phenol were investigated. The Al · Ni/SiO2 Supported catalyst was used, the conversion of phenol was almost 100%. The product was in the form of a mixture of mono-styrenated phenol, di-styrenated phenol and tri-styrenated phenol. The styrenated phenol were selectivity of the varies depending on the reaction conditions.

Synthesis of the Molybdenum Precursor for Slurry-Phase Hydrocracking of Heavy Oil

In this study, Molybdenum precursors were synthesized with butanoic acid, hexanoic acid, nonanoic acid, decanoic acid, and undecanoic acid. In order to determine chemical structure of Synthesized molybdenum precursors, 1H(13C)-NMR, EA and ICP were used pyrolysis properties were measured TGA. The molybdenum precursors was used for Hydrocracking of Vacuum R1esidue (VR). It was shown that molybdenum nonanoate(3) was shown the lowerst Toluene Insoluble and Gas Product about 2.1 and 5.0 percent.

Photoacid Catalyzed Reaction of Phenol with Styrene

The reaction of styrene with phenol using photoacid catalyst has been investigated. Upon irradiation with 450 nm light, protonated merocyanine photoacid converts into spiropyran form with releasing proton. The reaction of styrene with phenol has been conducted under irradiation with 450 nm light using merocyanine photoacid catalyst at room temperature in comparison with the results using some selected catalysts including or at the reaction temperature of .

Effect of Molar Concentration of NH4OH on Photocatalytic Activity in Preparation of Nanosized TiO2 Powder from Spent Titanium Chip by Sol-Gel Method.

The TiO2 powder was prepared from the spent titanium chips by applying the sol-gel method. The spent titanium chip was dissolved in HCl solution, and then NH4OH solution was added. The molar concentration of NH4OH solution was 2 M, 4 M, 8 M, and 10 M. Obtained TiO2 powders were calcined at 200 degrees C, 400 degrees C, and 600 degrees C. The prepared TiO2 powder was characterized using a particle size analysis, BET surface area, and XRD analysis. The crystal structure of the TiO2 powder was rutile type and anatase. The highest BET surface area of TiO2 powder was 432.8 m2/g. The photocatalytic property of the TiO2 powder was evaluated as decomposition rate of methylene blue(MB) by using a liquid phase stirred reactor. UV source was a UV-A, and concentration of MB in most experiments was 8 ppm. The concentration of MB was measured by absorbance at 664 nm using UV spectroscopy. Photocatalytic efficiency of prepared TiO2 powder depended highly on concentration of NH4OH solution. The TiO2 powder prepared with 8 M-NH4OH solution showed the highest efficiency, the decomposition efficiency at decomposition time of 2 hr and MB concentration of pH 8 was 98%.