• Journal of Photoscience
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• v.6 no.3
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• pp.91-96
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• 1999

Zeolites and microporouos materials continue to attract attention as novel hosts for photochemical reactions. Zeolities are attractive because of their ability to selectivity exchange and incorporate species within the void spaces and interconnecting channels, providing a spatial arrangement of molecules. Our research has primarily focused on intrazeolitic electron transfer from excited Ru(bpy)32+ in supercages of zeolite Y to a series of bipyridinium ions. In the Ru(bpy)32+ viologen-zeolite Y samples, the slowing of the back electron transfer from the bipyridinium radical cation to Ru(bpy)32+ allows for charge propagation via self exchange between diquat molecules. This provides an opportunity for permanent charge separation. When the migrating charge on the diquat radical within the zeolite reaches the surface, it can be transferred to a neutral viologen (PVS) in solution, resulting in permanent charge separation. The advantage of long-lived charge separation can be exploited for useful chemistry if suitable catablysts can be assembled on the zeolities. We have studied Ru(bpy)2 as water oxdiation catalysts. We have demonstrated that synthesis of RuO2 fibers on a zeolite via thermal decomposition of Ru3(CO)12 leads to the most active water decomposition catalyst reported to date. Because of the extensive interest of photochemical water reduction to H2, much is known about catalytic systems usin gone electron catalyst, and even more importantly, that no reaction of viologen occurred with H2 over this catalyst. The present challenge is to incorporate all these elements of the system into an architecture and we are examining zeolite membranes for this purpose.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.5
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• pp.301-306
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• 2011

In this study, zeolite was synthesized by hydrothermal, fusion, and fusion/hydrothermal methods with fly ash, coal fly ash, and a waste catalyst discharged from thermal power plants and incinerator in Ulsan area. Coal fly ashes (CFAs) and a waste catalyst containing amounts of $SiO_2$ and $Al_2O_3$ ranging from 60.29 to 89.62 wt%. CFAs were mainly composed of quartz and mullite which were assayed by a XRD pattern. Zeolite could be synthesized by CFAs and the waste catalyst when all methods were used. Na-A zeolite (Z-C1, Z-C2, and Z-W5) are mainly synthesized by the fusion method from CFAs and the waste catalyst. Z-C1 and Z-C2 formed by-products, calcite peaks, which is caused by the content of CaO in CFAs and the addition of $Na_2CO_3$ for a synthetic process.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.442-448
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• 2012

The effects of zeolite-type catalysts addition on the thermal decomposition of the PP resin have been studied in a thermal analyzer, a Pyrolyser GC-mass, and a small batch reactor. The zeolite type catalysts tested were natural zeolite, used FCC catalyst, and ZSM-5. As the results of TGA experiments, the pyrolysis starting temperature for PP varied in the range of $330{\sim}360^{\circ}C$ according to the heating rate. Addition of the zeolite type catalysts in the PP resin increased the pyrolysis rate in the order of used FCC catalyst> natural zeolite> ZSM-5 > PP resin. Adding the used FCC catalyst in the PP reduced most effectively the pyrolysis finishing temperature. In the PY-G.C. mass experiments, addition of zeolite type catalysts decreased the molecular weight of pyrolyzed product. In the batch system experiments, the mixing of used FCC catalyst enhanced best the initial yield of fuel oil, but the final yield of fuel oil was 2% higher in the case of mixing of natural zeolite. Also in the carbon number analysis, used FCC catalyst was the most useful one in this experiments for fuel oil.

• Bulletin of the Korean Chemical Society
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• v.22 no.11
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• pp.1177-1178
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• 2001

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.155-160
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• 2011

Dimethyl ether draws an attention as a green fuel in recent years. In this study, we investigated dehydration of methanol to produce DME using solid-acid catalysts, a series of zeolite. We found that ceria took a role of promoting the reaction conversion as well as selectivity of DME formation as a cocatalyst to the zeolite catalyst. We varied Si/Al ratio and ceria percentage on the surface of the catalyst to get high performance catalyst. ZSM5-30 with 5 wt% ceria on the surface was found to have excellent DME selectivity and to be little influenced by water content in methanol feed. We proposed a reaction model and obtained kinetic parameters for the DME formation using the catalyst based on experimental results using a microreactor.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.387-392
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• 2006

(Fe, Co)/zeolite catalysts such as (Fe, Co)/NaY, (Fe, Co)/NaBeta and (Fe, Co)/HUSY were prepared by ion-exchange method and their catalytic performance was examined in the hydroxylation of phenol with $H_2O_2$ for the production of catechol. The (Fe, Co)/NaBeta catalyst showed its best performance at reaction temperature=$70^{\circ}C$, molar ratio of phenol/$H_2O_2=3$, weight ratio of phenol/catalyst=50 and weight ratio of solvent (water)/phenol=6 as 20％ of phenol conversion, 77％ of the selectivity for the hydroxylation, 70％ of the selectivity for catechol, and 2.5 of the formation ratio of catechol/hydroquinone. The (Fe, Co)/zeolite catalysts showed the reproducible activities without deactivation after repeated regeneration. The fresh and used(Fe, Co)/zeolites were characterized by XRD, UV-VIS DRS, and XPS and their catalytic performance was discussed based on these characterization results.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.452-457
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• 2005

Foam-type MFI zeolite catalyst was prepared by dispersing fine ($-0.2{\mu}m$) particles of MFI zeolite on silicalite foam. Catalytic cracking of n-octane was investigated over the foam-type catalyst and Delplot method was employed to interpret product compositions for deducing reaction mechanism. The Si/Al molar ratio of dispersed MFI zeolite was estimated 25 and its dispersed amount of silicalite foam was 25 wt％. Since the apparent density of the foam type catalyst was very low $0.11g{\cdot}cm^{-3}$, the catalyst loading amount could be varied from 0.02 g to 0.5 g without concerning pressure drop, providing a wide variance in the residence time of the reactants and products. The conversion and olefin yield in the catalytic cracking of n-octane increased with the catalyst loading. The product composition was very simple and could be explained by applying the protolytic cracking mechanism when the catalyst loading was small. Higher loading of the catalyst brought about further reactions of cracked products, accumulating lower olefin and paraffin with low reactivity in product stream and resulting in complex product composition.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.339-341
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• 2008

Catalytic trimerization of isobutene to produce triisobutenes has been performed over cation-exchange resin and zeolite catalysts. Resin catalysts have the advantage of long lifetime and high trimers selectivity even though the regeneration of an aged catalyst is not satisfactory. On the contrary, zeolite catalysts can be regenerated facilely by simple calcination in air even though the lifetime is short and trimers selectivity is low probably due to small pore size and strong acidity, respectively. It is, therefore highly desirable to develop an inorganic acid catalyst with macro- or meso-pores to show catalytic performances similar or superior to those of macroporous resin catalysts.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.614-617
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• 2012

Ti-containing zeolite was synthesised and used in the epoxidation of di-cyclopentadiene (DCPD). Among various Ti-zeolite catalysts, Y contained Ti-zeolite showed the highest yield in the epoxidation of DCPD. The study was also investigated in terms of the Ti content in the catalysts, $H_2O_2$/substrate ratio, reaction temperature and applied time. The reaction conditions significantly influenced on both the catalytic activity and selectivity. In addition, Ti structure in the zeolite was analyzed using IR and UV-vis spectroscopy.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1996.04a
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• pp.22-22
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• 1996