• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.341-347
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• 2008

The feasibility of commercializing the hydrothermal synthesis of Na-A type zeolite from siliceous mudstone has been conducted using a 50-liter bench-scale autoclave and the application of the zeolite as an environmental remediation agent. Siliceous mudstone, which is widely distributed around the Pohang area, was adopted as a precursor. The siliceous mudstone is favorable for the synthesis of zeolite because it contains 70.7% $SiO_2$ and 10.0% $Al_2O_3$, which are major ingredient of zeolite formation. The synthesis of zeolite was carried out under the following conditions that had been obtained from the previous laboratory-scale tests: 10hr reaction time, $80^{\circ}C$ reaction temperature, $Na_2O/SiO_2$ ratio = 0.6, $SiO_2/Al_2O_3$ ratio = 2.0 and $H_2O/Na_2O$ ratio= 98.6. The crystallinity and morphology of the zeolite formed were similar to those obtained from the laboratory-scale tests. The recovery and cation exchange ion capacity were 95% and 215 cmol/kg, respectively, which are slightly higher than those obtained in laboratory scale tests. To examine the feasibility of the zeolite as an environmental remediation agent, experiments for heavy metal adsorption to zeolite were conducted. Its removal efficiencies of heavy metals in simulated waste solutions decreased in the following sequences: Pb > Cd > Cu = Zn > Mn. In a solution of 1500 mg/L total impurity metals, the removal efficiencies for these impurity metals were near completion (> 99%) except for Mn whose efficiency was 98%. Therefore, the synthetic Na-A type zeolite was proven to be a strong absorbent effective for removing heavy metals.

• Clean Technology
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• v.25 no.1
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• pp.81-90
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• 2019

A dielectric barrier discharge (DBD) plasma reactor packed with $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst was used for the dry ($CO_2$) reforming of propane (DRP) to improve the production of syngas (a mixture of $H_2$ and CO) and the catalyst stability. The plasma-catalytic DRP was carried out with either thermally or plasma-reduced $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst at a $C_3H_8/CO_2$ ratio of 1/3 and a total feed gas flow rate of $300mL\;min^{-1}$. The catalytic activities associated with the DRP were evaluated in the range of $500{\sim}600^{\circ}C$. Following the calcination in ambient air, the ${\gamma}-Al_2O_3$ impregnated with the precursor solution ($Ni(NO_3)_2$ and $Ce(NO_3)_2$) was subjected to reduction in an $H_2/Ar$ atmosphere to prepare $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst. The characteristics of the catalysts were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDS), temperature programmed reduction ($H_2-TPR$), temperature programmed desorption ($H_2-TPD$, $CO_2-TPD$), temperature programmed oxidation (TPO), and Raman spectroscopy. The investigation revealed that the plasma-reduced $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst exhibited superior catalytic activity for the production of syngas, compared to the thermally reduced catalyst. Besides, the plasma-reduced $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst was found to show long-term catalytic stability with respect to coke resistance that is main concern regarding the DRP process.

• The Korean Journal of Nuclear Medicine
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• v.33 no.3
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• pp.298-305
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• 1999

Purpose: N-(3-[$^{18}F$]Fluoropropyl)-$2{\beta}$-carbomethoxy-$3{\beta}$-(4-iodophenyl)nortropane [$^{18}F$]FP-CIT) has been shown to be very useful for imaging the dopamine transporter. However, synthesis of this radiotracer is somewhat troublesome. In this study, we used a new method for the preparation of [$^{18}F$]FP-CIT to increase radiochemical yield and effective specific activity. Materials and Methods: [$^{18}F$]FP-CIT was prepared by N-alkylation of nor-${\beta}$-CIT (2 mg) with 3-bromo-1-[$^{18}F$]fluoropropane in the presence of $Et_3N$ (5-6 drops of $DMF/CH_3CN$, $140^{\circ}C$, 20 min). 3-Bromo-1-[$^{18}F$]fluoropropane was synthesized from $5{\mu}L$ of 3-bromo-1-trifluoromethanesulfonyloxypropane (3-bromopropyl-1-triflate) and $nBu_4N^{18}F$ at $80^{\circ}C$. The final compound was purified by reverse phase HPLC and formulated in 13% ethanol in saline. Results: 3-Bromo-1-[$^{18}F$]fluoropropane was obtained from 3-bromopropyl-1-triflate and $nBu_4N^{18}F$ in 77-80% yield. N-Alkylation of nor-${\beta}$-CIT with 3-bromo-1-[$^{18}F$]fluoropropane was carried out at $140^{\circ}C$ using acetonitrile containing a small volume of DMF as the solvents. The overall yield of [$^{18}F$]FP-CIT was 5-10% (decay-corrected) with a radiochemical purity higher than 99% and effective specific activity higher than the one reported in the literature based on their HPLC data. The final [$^{18}F$]FP-CIT solution had the optimal pH (7.0) and it was pyrogen-free. Conclusion: In this study, 3-bromopropyl-1-triflate was used as the precursor for the [$^{18}F$]fluorination reaction and new conditions were developed for purification of [$^{18}F$]FP-CIT by HPLC. We established this new method for the preparation of [$^{18}F$]FP-CIT, which gave high effective specific activity and relatively good yield.