• Journal of Korean Society for Atmospheric Environment
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• v.13 no.1
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• pp.91-98
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• 1997

Y-zeolite and ${\gamma}$-Al$_2$O$_3$ were used as supports on CO and $C_3$H$_{6}$ oxidation for diesel emission control. The catalysts composed of Pd and Pt as active components were wash coated on honeycomb type ceramic substrate. The oxidation of CO and $C_3$H$_{6}$ was carried out over prepared honeycomb in a fixed bed continuous reactor in the temperature range of 20$0^{\circ}C$~50$0^{\circ}C$ and 20,000 GHSV (h$^{-1}$ ). Surface area of Y-zeolite was larger than that of ${\gamma}$-Al$_2$O$_3$ due to channel structure of Y-zeolite. Therefore, high conversion of CO and $C_3$H$_{6}$ could be obtained because of good dispersion of active metals over Y-zeolite. The honeycomb used Y-zeolite as a support showed higher $C_3$H$_{6}$ conversion than that of ${\gamma}$-Al$_2$O$_3$ due to better cracking and isomerization activity of Y-zeolite. PdPt catalyst showed high conversion of CO and $C_3$H$_{6}$ at low temperature region, 20$0^{\circ}C$~30$0^{\circ}C$, for their synergy effects. PdPt/Y-Zeolite catalyst could achieve more than 80％ conversion of $C_3$H$_{6}$ at 30$0^{\circ}C$. The use of Y-zeolite as a support increased CO and $C_3$H$_{6}$ conversion, and decreased SO$_2$ conversion very effectively. Y-zeolite found to have a good adaptability as a support for the diesel emission after treatment system.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.450-457
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• 2015

In this research a adsorbent, PVA-Zeolite bead, was prepared by immobilizing zeolite with PVA. The results of XRD and SEM analysis showed that the prepared PVA-Zeolite beads had porous structure and the zeolite particles were in mobilized within the internal matrix of the beads. The adsorption properties of Sr ion and Cs ion with the adsorbent were studied by different parameters such as effect of pH, adsorption rate, and adsorption isotherm. The adsorption of Sr ion and Cs ion reached equilibrium after 540 minutes. The adsorption kinetics of both ions by the PVA-Zeolite beads were fitted well by the pseudo-second-order model more than pseudo-first-order model. The equilibrium data fitted well with Langmuir isotherm model. The maximum adsorption capacities of Sr ion and Cs ion calculated from Langmuir isotherm model were 52.08 mg/g and 58.14 mg/g, respectively. The external mass transfer step was very fast compared to the intra-particle diffusion step in the adsorption process of Cs ion and Sr ion by the PVA-Zeolite beads. This result implied that the rate controlling step was the intra-particle diffusion step.

• Applied Biological Chemistry
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• v.31 no.1
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• pp.86-91
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• 1988

Natural zeolite rock of which dominent clay minerals were mordenite and clinoptilolite was collected from Wolsung, Kyungpook province. It was pulverized and sieved into four fractions of $1{\sim}0.5,\;0,5{\sim}0.25,\;0.25{\sim}0.1,$ and<0.1mm. The specific surface areas of its four fractions were determined by $H_2O$ and EGME. The specific surface area of zeolite was slightly affected according to species of measuring material, but was scarcely affected by partical size, nor increased of pulverizing. The surface area of zeolite was calculated from geometric structure of mordenite and it was compared with the specific surface area calculated from maximum numbers of $H_2O$ which could be adsorbed on mordenite. On the basis of that result, the specific area measured from zeolite was estimated to be a part of surface area calculated from it. Accordingly, it was suggested that a new method should be developed for the determination of an exact surface area of zeolite.

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.530-533
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• 1998

Chemical vapor deposition of $TiCl_4$ followed by the hydrolysis thereof at elevated temperatures was employed for the formation of $TiO_2$ clusters inside ZSM-5 matrix. BET and XRD revealed that the zeolite structure remains intact. XPS, Raman, FTIR, and UV-VIS reflectance spectroscopy indicated that $TiO_2$ particles thus formed are extremely small and localized inside the zeolite matrix.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.361-372
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• 1994

Vanadium containing MFI type zeolites have been prepared hydrothermally or by the impregnation method with $NH_4VO_3$ solution after dealumination of HZSM-5. Incorporation of vanadium into the framework of zeolite has been demonstrated by XRD, DTA, FT-IR and ESR analyses. Upon $NH_4VO_3$ impregnation and calcination of dealuminated zeolite, vanadium substitution into the framework could be performed like a hydrothermally synthesized zeolite. Vanadium in zeolite is able to pass redox cycles at high temperatures, and it is shown that vanadium is probably fixed and atomically dispersed in the structure of zeolite. The catalytic benzene hydroxylation, hexanes and alcohols oxidation were used for evaluating the properties of vanadium incorporated MFI zeolite.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.265-270
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• 1991

Theoretical calculations on the stabilization energies of framework atoms in hydrolyses Co(Ⅱ )-exchanged zeolite A were made using some potential energy functions and optimization program. The protons which are produced by hydrolysis of $[Co(H_2O)_n]^{2+}$ ion in large cavity showed a tendency to attack the framework oxygen atom O(1) preferentially, and the oxygen atom O(4) within OH- ion was coordinated at Al atom. The weakness of bonds between T(Si, Al) and oxygen by attack of proton and too large coordination number around small aluminum atom will make the framework of Co(Ⅱ)-exchanged zeolite A more unstable. The stabilization energy of $Co_4Na_4$-A framework (- 361.57 kcal/mol) was less than that of thermally stable zeolite A($Na_{12-}$A: - 419.68 kcal/mol) and greater than that of extremely unstable Ba(Ⅱ)-exchanged zeolite A($Ba_{6-}$A: - 324.01 kcal/mol). All the data of powder X-ray diffraction, infrared and Raman spectroscopy of Co(Ⅱ)-exchanged zeolite A showed the evidence of instability of its framework in agreement with the theoretical calculation. Three different groups of water molecules are found in hydrated Co(Ⅱ )-exchanged zeolite A; W(Ⅰ) group of water molecules having only hydrogen-bonds, W(Ⅱ) group water coordinated to $Na^+$ ion, ans W(Ⅲ) group water coordinated to Co(Ⅱ) ion. The averaged interaction energy of each water group shows the decreasing order of W(Ⅲ)>W(Ⅱ)>W(Ⅰ).

• Korean Journal of Environmental Agriculture
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• v.19 no.5
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• pp.401-418
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• 2000

1. Production of the artificial zeolite from coal ash Coal fly ash is mainly composed of several oxides including $SiO_2$ and $Al_2O_3$ derived from inorganic compounds remained after burning. As minor components, $Fe_2O_3$ and oxides of Mg, Ca, P, Ti (trace) are also contained in the ash. These components are presented as glass form resulting from fusion in the process of the combustion of coal. In other word, coal ash may refer to a kind of aluminosilicate glass that is known to easily change to zeolite-like materials by hydrothermal reaction. Lots of hot seawater is disposing near thermal power plants after cooling turbine generator periodically. Using seawater in the hydrothermal reaction caused to produce low price artificial zeolite by reduction of sodium hydroxide consumption, heating energy and water cost. As coal ash were reacted hydrothermally, peaks of quartz and mullite in the ash were weakened and disappeared, and new Na-Pl peaks were appeared strengthily. Si-O-Si bonding of the bituminous coal ash was changed to Si-O-Al (and $Fe^{3+}$) bonding by the reaction. Therefore the produced Na-Pl type zeolite had high CEC of 276.7 $cmol^+{\cdot}kg^{-1}$ and well developed molecular sieve structure with low concentration of heavy metals. 2. Utilization of the artificial zeolite in agro-environment The artificial zeolite(1g) could remove 123.5 mg of zinc, 164.7 mg copper, 184.4 mg cadmium and 350.6 mg lead in the synthetic wastewater. The removability is higher 2.8 times in zinc, 3.3 times in copper, 4.7 times in cadmium and 4.8 times in lead than natural zeolite and charcoal powder. When the heavy metals were treated at the ratio of 150 $kg{\cdot}ha^{-1}$ to the rice plant, various growth inhibition were observed; brownish discoloration and death of leaf sheath, growth inhibition in culm length, number of panicles and grains, grain ripening and rice yield. But these growth inhibition was greatly alleviated by the application of artificial zeolite, therefore, rice yield increased $1.1{\sim}3.2$ times according to the metal kind. In addition, the concentration of heavy metals in the brown rice also lowered by $27{\sim}75%$. Artificial Granular Zeolites (AGZ) was developed for the purification of wastewater. Canon exchange capacity was 126.8 $cmol^+{\cdot}kg^{-1}$. AGZ had Na-Pl peaks mainly with some minor $C_3S$ peaks in X-ray diffractogram. In addition, AGZs had various pore structure that may be adhere the suspended solid and offer microbiological niche to decompose organic pollutants. AGZ could remove ammonium, orthophosphate and heavy metals simultaneously. Mixing ratio of artificial zeolite in AGZs was related positively with removal efficiency of $NH_4\;^+$ and negatively with that of $PO_4\;^{3-}$. Root growth of rice seedling was inhibited severely in the mine wastewater because of strong acidity and high concentration of heavy metals. As AGZ(1 kg) stayed in the wastewater(100L) for 4days, water quality turned into safely for agricultural usage and rice seedlings grew normally.

• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1277-1280
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• 2005

• Bulletin of the Korean Chemical Society
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• v.14 no.3
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• pp.356-362
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• 1993

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.623-628
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• 2004

Zeolite SUZ-4 was successfully synthesized with TEAOH (Tetraethyl ammonium hydroxide) as structure directing agent under a vigorous stirring condition. Well-defined zeolite SUZ-4 structure was only obtained under stirring of 250 rpm or more. The results imply that stirring plays a pivotal role for reproducible synthesis. Morphology of SUZ-4 crystal was controlled by adjustment of water concentrations. The physicochemical characterization of SUZ-4 and its hydrothermal stability using a steam treatment were investigated by using XRD, BET, and $NH_3-TPD$.