• Journal of Aerospace System Engineering
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• v.11 no.2
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• pp.9-15
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• 2017

In order to verify the possiblity of improving the combustion performance of ethanol using zeolite catalyst and the characteristics of nitrogen oxides and carbon monoxide emission, micro gas turbine experiments were performed using catalytic reaction products, ethanol and kerosene as fuels and the results were compared. The thrust of the catalytic reaction product was lower than that of kerosene, but it was improved by 5% on average compared with the use of ethanol. Nitrogen oxides and carbon monoxide emissions of the catalytic reaction products were measured to be very low overall compared to kerosene. As a result, when the ethanol was reformed using the zeolite catalyst, the engine performance could be improved while maintaining the environment friendliness of the ethanol.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.137-146
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• 1992

The adsorption properties of CO on the cation exchanged natural zeolite, $K_{111}$ and cation effects upon the CO adsorption were studied. $Na^+-,\;Cu^{2+}-\;and\;Ba^{2+}-\;K_{111}$ exhibited relatively good CO adsorption capacities and $Ba^{2+}- K_{111}$ treated by 0.4 N-$BaCl_2$ solution proved itself as the best adsorbent and superior to the synthetic zeolite 4A and 5A. The observed adsorption tendency due to the cations were in the order of $Ba^{2+}>Cu^{2+}>Na^+>K^+>Mg^{2+}>Ca^{2+}$. The cation exchanged number per unit cell as well as the kind of cation which forms bond with CO molecules in different intensities and other mineral factors such as pore size indicated to be important factors to the CO adsorption properties. The CNDO/2 calculations were performed to compare the adsorption tendencies and CO interaction energy of cations in $K_{111}$.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.949-956
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• 1994

The objective of this study is to experimentally investigate the ion exchange characteristics of five types of Zeolite(Zeolite-A, 13X, Y, Mordenite, Chabazite) for effective removal of Cs, Sr and Co ions in water solution at low concentration(0.01 N and 0.005 N). Total ion exchange capacity and equilibrium isotherm are measured, and free-energy change(${\Delta}G^0$) and enthalpy change(${\Delta}H^0$) in ion exchange reaction are calculated from experimental results. In addition the ion exchange equilibrium in the three-component system for three types of zeolite showing better efficiency is measured and plotted in triangle coordinates. It is shown from experimental results that the magnitude of free-energy change increases with the increasing ion selectivity, and the difference of free energy change between ions correlates closely with that of ion selectivity. The results also shows that Chabazite is effective for the adsorption of Cs ion, and Zeolite-A and Zeolite-13X for that of Sr and Co ions.

• Journal of the Korean Chemical Society
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• v.38 no.5
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• pp.339-344
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• 1994

The crystal structure of a methanol sorption complex of dehydrated partially Co(II)-exchanged zeolite A, $Co_4Na_4-A{\cdot}6.5CH_3OH$ (a = 12.169(1) $\AA)$, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm$\bar3$m at $21(1)^{\circ}C. $Co_4Na_4$-A was dehydrated at $360^{\circ}C\;and\;2{\times}10^{-6}$ torr for 2 days, followed by exposure to about 104 torr of methanol vapor at $22(1)^{\circ}C$ for 1 hr. The structure was refined to final error indices, $R_1$ = 0.061 and $R_2$ = 0.060 with 147 reflections, for which I > $3\sigma(I).$ In this structure, four $Co^{2+}$ ions and 1.5 $Na^+$ ions per unit cell lie at 6-ring positions: the $Na^+$ ions are recessed 0.44 $\AA$ into the sodalite unit and the Co(II) ions extend ca. 0.55 $\AA$ into the large cavity. 2.5 $Na^+$ ions lie in an 8-oxygen ring plane. The 6.5 methanol molecules are sorbed per unit cell. The 6.5 methanol oxygens, all in the large cavity, associate with the 4 $Co^{2+}$ ions and 2.5 $Na^+$ ions.

• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.98-105
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• 2013

The NaA zeolite particles were dispersed in a poly(vinyl alcohol) (PVA) matrix to prepare a composite membrane. The nano sized zeolite particles of NaA were synthesized in the laboratory and the mean size was approximately 60 nm. Pervaporation characteristics such as a permeation flux and a separation factor were investigated using the membrane as a function of the feed concentration from 0.01 to 0.05 mole fraction and the weight % of NaA particles between 0 wt% and 5 wt% in the membrane. Also, the micro sized particles of $5{\mu}m$ were dispersed in the membrane for a comparison purpose. When the ethanol concentration in the feed solution was 0.01 mole fraction, the flux of water significantly increased from $600g/m^2/hr$ to $2000g/m^2/hr$ as the content of the nano NaA particles in the membrane increased from 0 wt% to 5 wt%, while the NaA particles improved the separation factor from 1.5 to 7.9. When the flux of water through the membrane containing nano sized particles was roughly 15% increased compared to the micro sized particles, whereas the separation factor of water was found to be approximately 5% increased. It can be said that the role of the nano sized NaA particles is quite important since both the flux and the separation factor are strongly affected.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.5
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• pp.204-210
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• 2004

Though the recycling rate of coal fly ash generated from domestic thermoelectric power plants is gradually increased, at present, the most amount of coal bottom ash is disposed by a landfill instead of recycling. Therefore, to reuse a coal bottom ash as high-value materials the synthesis of zeolite made from a coal bottom ash was investigated in this study. NaPl, hydroxy-sodalite and tobermorite were produced through the alkaline hydrothermal reaction of pulvelized bottom ash at various temperatures; 80, 120, $150^{\circ}C$, and the concentration of NaOH at the range from 1 to 5 M. Especially, NaPl with excellent cation exchange capability had a high crystallinity at ${\leq}2$ M NaOH and ${\leq}120^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.3
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• pp.145-151
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• 2015

In order to remove Sr ions and Cs ions from aqueous solution, PS-zeolite beads were prepared by immobilizing zeolite with polysulfone (PS). The prepared PS-zeolite beads were characterized by SEM, XRD, FT-IR, and TGA. The optimum condition to prepare PS-zeolite beads was 1.25 g of PS content and 2 g of zeolite A. The removal efficiencies of Sr and Cs ions by the PS-zeolite beads increased as the solution pH increases and nearly reached a plateau at pH 4. The PS-zeolite beads prepared in this study showed a remarkably high selectivity for Sr ion and Cs ion under the coexistence of ions such as $Na^+$, $K^+$, $Mg^{2+}$, and $Ca^{2+}$. Zeolite particles detached from the PS-zeolite beads were not observed on this experiments, and also the PS-zeolite beads maintained the morphological structure on a SEM image. The removal efficiencies of Sr ions and Cs ions by PS-zeolite beads were maintained over 90% even after five adsorption-desorption cycles. These results implied that the prepared PS-zeolite beads could be an available adsorbent for the adsorption of Sr and Cs ions. These results suggest that the PS-zeolite can potentially be used as an adsorbent in radioactive ions removal for the treatment of industrial wastewater.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.594-603
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• 2018

The effects of operating conditions such as benzene concentration, nitrogen flow rate, steam flow rate, and bed temperature on TSA process were experimentally investigated as a potential VOC removal technology using two kinds of beds packed with activated carbon and zeolite 13X. The TSA cycle studied was composed of the adsorption step, steam desorption step, and drying and cooling step. At 2% benzene concentration, the total adsorption amounts of zeolite 13X and activated carbon were 4.44 g and 3.65 g, respectively. Since the zeolite 13X has a larger packing density than that of the activated carbon, the larger benzene amount could be adsorbed in a single cycle. Increasing the water vapor flow rate to 75 g/hr at 2% benzene concentration reduced the desorption time from 1 hr to a maximum of 33 min. If the desorption time is shortened, the drying and cooling step period can be relatively increased. Accordingly, the steam removal and bed cooling could be sufficiently performed. The desorption amounts increased with the increase of the bed temperature. However, the energy consumption increased while the desorption amount was almost constant above $150^{\circ}C$. In the continuous cycle process, when the amount of remained benzene at the completion of the regeneration step increased, it might cause a decrease in the working capacity of the adsorbent. The continuous cycle process experiment for zeolite 13X showed that the amount of remained benzene at the end of regeneration step maintained a constant value after the fourth cycle.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.509-512
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• 2009

Powder diffraction patterns of the zeolite mesolite ($Na_{5.33}Ca_{5.33}Al_{16}Si_{24}O_{80}{\cdot}21.33H_2O$), with a natrolite framework topology were measured as a function of pressure up to 5.0 GPa using a diamond-anvil cell and a $200{\mu}m$-focused monochromatic synchrotron X-ray. Under the hydrostatic conditions mediated by pore-penetrating alcohol and water mixture, the elastic behavior of mesolite is characterized by continuous volume expansion between ca. 0.5 and 1.5 GPa, which results from expansion in the ab-plane and contraction along the c-axis. Subsequent to this anomalous behavior, changes in the powder diffraction patterns suggest possible reentrant order-disorder transition. The ordered layers of sodium- and calcium-containing channels in a 1:2 ratio along the b-axis attribute to the $3b_{natrolite}$ cell below 1.5 GPa. When the volume expansion is completed above 1.5 GPa, such characteristic ordering reflections disappear and the $b_{natrolite}$ cell persists with marginal volume contraction up to ca. 2.5 GPa. Further increase in pressure leads to progressive volume contraction and appears to generate another set of superlattice reflections in the $3c_{natrolite}$ cell. This suggests that mesolite in the pressure-induced hydration state experiences order-disorder-order transition involving the motions of sodium and calcium cations either through cross-channel diffusion or within the respective channels.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.488-494
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• 2009

Zeolite 4A was prepared by new synthesis method, 2-step crystallization, for enhancement of oil absorption capacity. Vietnamese sand and $NaAlO_2$ solution from natural bauxite were used as raw materials in stead of conventional cullet and $Al(OH)_3$ to reduced the processing cost. Some dissolved organics in $NaAlO_2$ solution were removed by activated carbon. Synthetic method was progressed by 1) reacting the raw materials at $55^{\circ}C$, 4 hr with the ratio of Si/Al to 1.15, and 2) reacting at $65^{\circ}C$, 5 hr with reducing the ratio of Si/Al to 0.98. New method can easily control the particle size, aggregation, surface polarity, and enhanced the whiteness of the products. The prepared zeolite 4A shows excellent oil absorption capacity(O.A.C>50 ml/100 g) as well as equal value with calcium ion exchange capacity, and proves the 2-step crystallization is the economic and effective process for the preparation of zeolite 4A.