Geon Joong Kim

The reaction of CO2 with CH4 to synthesize H2 and CO over nickel-loaded Y-zeolites

Nickel metal introduced into Y-zeolite exhibited a high catalytic activity in the dehydro-genation of methane and in the hydrogenation of carbon dioxide with methane to obtain hydrogen and CO at about 850 K. The activity strongly depended on the nickel amount in NaY, and the catalytic properties were influenced by the kind of cations in the Y-zeolite. The higher CO2 conversion was obtained over Ni supported on non-acidic zeolites.

Direct synthesis and characterization of high-SiO2-content mordenites

A direct synthesis of high-SiO 2 -content mordenite without addition of organic compounds was studied. The effects of starting raw materials, substrate composition, aging time, and reaction temperature on the crystallization rates were investigated. Morphology, N 2 sorption capacity, surface area, thermal stability of crystals, and hexane-cracking property of the silica-rich mordenite are also reported.

Structure modification of mordenite through isomorphous Ti substitution: Characterization and catalytic properties

The introduction of Ti atoms by means of TiCl4 treatment and hydrothermal synthesis has been applied to mordenite zeolite with different structures from silicalite. The incorporation of Ti into the mordenite framework is demonstrated by XRD, FTIR,29Si MAS NMR techniques, and tested with catalytic oxidation reactions. Ti-Al-mordenite catalyses the oxidation ofn-hexane, cyclohexane and benzene with hydrogen peroxide under very mild conditions. These reactions can be performed in methanol, acetonitrile and water as solvents. The rate of the reaction is strongly affected by the kind of solvent.

Synthesis of a Siliceous MCM-41 using C22TMACl Template and Preparation of Heterogenized New Chiral Salen Complexes

Purely siliceous MCM-41 has been prepared under both mild and acidic conditions by a solvent evaporation method using C16TMABr and C22TMACl surfactant as templates. A hydrothermal synthesis was also carried out by utilizing a method of adjusting the gel pH to 10. The mesoporous samples synthesized in ethanol solvent by using this evaporation method showed a fully disordered pore system, but those obtained in the hydrothermal synthesis had highly ordered pores. The chiral salen Mn(III) complexes were immobilized on the siliceous MCM-41 by a new grafting method using 3-aminopropyltrimethylsilane and diformylphenols. These ligands on MCM-41 were stable during the reactions. High enantioselectivities were displayed in the epoxidation of styrene by using these heterogenized salen complexes.

Synthesis and Characterization of Co-Surfactant Templated Mesoporous Materials with Enhanced Hydrothermal Stability

Ordered mesoporous materials with a hydrothermally-stable, protozeolitic framework were prepared by exploring the direct conversion of inorganic species based on co-surfactant templating systems. To confer hydrothermal stability on the mesoporous materials, the organic-inorganic hybrids were heat-treated in strongly basic media. Co-surfactant templating systems of cetyltrimethylammonium bromide [C16H13(CH3)3NBr, CTAB] with 1,3,5-trimethylbenzene (TMB) or a nonionic block copolymer of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (EO20PO70EO20) were employed to improve the hydrothermal stability of the organic-inorganic selfassembly during the solid rearrangement process of the inorganic species. The mesoscopic ordering of the pore structure and geometry was identified by X-ray diffraction, small angle neutron scattering and electron microscopy.

Structural effects on the tensile and morphological properties of zeolite-filled polypropylene derivative composites

We have studied the effects that inorganic zeolite powder have on structurally different copolymer [poly(propylene-co-ethylene)] and terpolymer [poly(propylene-co-ethylene-co-1-butene)] systems and the possibility of preparing suitable porous composite films. The impact strength and yield stress of the composites did not improve upon any further loading of zeolite, but the modulus increased gradually with respect to the filler loading. The experimental modulus of each of the two systems was compared with theoretical models. We performed a morphological study of the filler mixing efficiency and image analysis. The number-, weight-, and z-average air hole diameters were compared with respect to the draw ratio as well as the zeolite loading. The experimental results suggest that these two matrices can provide a new choice for preparing future multiphase polymeric porous films by stretching them unidirectionally. In particular, we suggest that a 40 wt% zeolite loading at a draw ratio of 4 is useful for porous film applications.

Structure and acidity modification of mordenite through isomorphous Fe substitution

A series of Fe-modified mordenite were hydrothermally synthesized. The effects of substrate composition, aging time, reaction temperature, and reaction time upon the crystallization of the mordenite were investigated. Isomorphous substitution of Fe was confirmed by FT-IR and EPR analysis. Acid strength and acid sites distribution of each catalyst were measured by pyridine TPD, which showed that the number of strong acid sites in H-Fe-mordenite are smaller than in H-Al-mordenite. Structural characteristics and thermal stability were also examined using XRD, SEM and TG. Fe-substitution into the mordenite structure have resulted in substantial decrease in thermal stability. H-Fe-mordenite catalysts showed high selectivity towards p-xylene in toluene alkylation and in xylene isomerization reaction, compared with those obtained using H-Al-mordenite because of lower concentration of strong acid sites. In addition, these H-Fe-modified mordenite showed little hexane cracking activity. Deactivation in both toluene alkylation and xylene isomerization reaction and coke formation over H-Fe-mordenite in these reactions were negligible.

Mesoporous silica MCM-41-supported norephedrine and ephedrine as heterogeneous chiral ligands in asymmetric catalysis

Mesoporous silica MCM-41-supported norephedrine (3a) and ephedrine (3b) were prepared from available amino alcohol and utilized as ligand for the ruthenium-catalyzed asymmetric transfer hydrogenation of ketones and for the asymmetric addition of diethylzinc to aromatic aldehydes respectively. The mesoporous silica MCM-41 was found to be potential inorganic support in the asymmetric catalysis.

Chiral (Salen) Complexes Encapsulated in Mesoporous ZSM-5 as an Optical Active Catalyst for Asymmetric Phenolic Ring Opening of Terminal Epoxides

ZSM-5 was modified by alkaline and acidic solution to introduce mesoporosity in the crystals. Heterogenized Co(III) salen was prepared in the mesopores of ZSM-5 by ‘ship-in-a-bottle’ method. Phenolic ring opening of epoxides was performed successfully by using encapsulated chiral salen catalysts. Very high enantioselectivity and conversion were obtained in PKR reaction by immobilized catalysts.

Decomposition of VOCs using mesoporous TiO2 in a silent plasma

Abstract The decomposition of benzene was carried out using a silent plasma (dielectric barrier discharge: DBD)-catalyst hybrid system. Several types of catalysts such as TiO 2 , and V 2 0 5 /Ti0 2 had been selected. It was found that benzene decomposition efficiency decreases in the following order: 1 wt% V 2 O 5 /TiO 2 catalyst > TiO 2 catalyst > only plasma discharge. In addition, presence of catalysts improved the CO 2 selectivity and suppressed the formation of N 2 O.