• Journal of Korean Society of Water and Wastewater
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• v.24 no.6
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• pp.775-788
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• 2010

The decomposition of 2,4,6-trinitrotoluene (TNT) and the mass balance of nitrogen (N) species as products were investigated in a UV/H2O2system by varying pH, concentrations of $H_2O_2$, and $O_2$. All experiments were conducted in a semi-batch system employing a 50 mL reaction vessel and a coil-type quartz-tube reactor. In contrast with previous studies employing batch mode, TNT decomposition in the semi-batch mode was proportionally enhanced by increasing $H_2O_2$ concentration to 10 mM (0.034%), indicatingthat an inhibitory effect of excess $H_2O_2$on hydroxyl radical (${\cdot}OH$) can be negligible. N compounds are released as $NO_2^-$ in the early stages of the reaction, but $NO_2^-$ is rapidly oxidized to $NO_3^-$ by means of ${\cdot}OH$. $NH_4^+$ was also detected in this study and showed gradually the increase with increasing reaction time. In this study, $NH_4^+$ production can involve the reduction of nitro group of TNT concurrent with the production of $NO_3^-$. Of the N species originating from TNT decomposition, 12 ~ 72% were inorganic forms (i.e. [$NO_3^-$] + [$NO_2^-$] + [$NH_4^+$]). This result suggests that the large remaining N portions indicate that unidentified N compounds can exist.

• Archives of Metallurgy and Materials
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• v.64 no.2
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• pp.695-700
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• 2019

Mordenite-zeolite supported Ca-Cu and Ba-Cu catalysts (Ca-Cu/MOR and Ba-Cu MOR) were successfully fabricated for direct decomposition of both NF₃ and N₂O gases contained in waste gas stream of (semiconductor) electronics industry. N₂O conversion rates of Ca-Cu and Ba-Cu catalysts were 79 and 86%, respectively, at 700℃ and 1 atm under space velocity of 5000 h^-1. The Ca-Cu catalyst was especially noteworthy in that its capability of converting N₂O could be maintained even after its exposure to co-feeding NF₃ gas constituent in the waste gas stream. Compositional and surface morphological analyses of the Ca-Cu and Ba-Cu catalysts were made before and after exposure to the waste gas stream to examine any noticeable degradation or change of the catalysts. Unlike Ba-Cu catalyst, SiO₂ constituent of the Ca-Cu catalyst was found to remain immune to the NF₃-cofeeding waste gas stream, casting a positive prospect for superior and steady N₂O decomposition performance via maintenance of its structural integrity.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.321-325
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• 1996

Quantum chemical calculations are used to characterize the decomposition of nitrogenmonoxide over $Cu^{n+}$-Y zeolite. The method of theoretical calculations, such as CNDO/2, have been applied to cluster models representing cation sites in zeolite to obtain total energies, LUMO energies, and Wiberg bond orders. The calculated total energies and bond orders of cluster models showed the reaction mechanism of NO decomposition over $Cu^{n+}$ site in zeolite framework. The suggested cluster models of varying Si/Al ratios studied with exchange cations in the $Cu^+$ and in the $Cu^{2+}$ states. And the calculated LUMO energies can predict L acidifies of cluster models. The results from these experiments showed the possibility of the mechanism of NO decomposition, progressing adsorption of NO, conversion to $N_2$ and $O_2$, desorption of $N_2$ and $O_2$ in sequence. The L acidity of $Cu^{2+}$ ion in cation site is more strong than $Cu^+$.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.82-87
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• 2008

$N_2O$ decomposition characteristics of dual bed mixed metal oxide catalytic system was investigated. The partial oxidation of methane at first reactor of dual bed catalytic system was performed over Co-Rh-Al (1/0.2/1) catalyst under the optimized condition of $8,000h^{-1}$ GHSV, gas ratio ($CH_4:O_2=5:1$) at $500^{\circ}C$. In the dual bed system investigated herein, the second catalyst bed was employed for the $N_2O$ decomposition using product of partial oxidation of methane at first bed. An excellent $N_2O$ conversion activity even at lower temperature ($<250^{\circ}C$) was obtained with Co-Rh-Al (1/0.2/1) or Co-Rh-Zr-Al (1/0.2/0.3/1) catalyst by combining Co-Rh-Al (1/0.2/1) hydrotalcite catalyst for the partial oxidation of methane in a dual-bed system. The $N_2O$ conversion activity is drastically reduced in the presence of oxygen in second bed of a dual-bed system over Co-Rh-Al (1/0.2/1) catalyst at $300^{\circ}C$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.58-61
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• 2009

The characteristics of nitrous oxide catalytic decomposition were studied to utilize the nitrous oxide as a propellant. The Ru and Pt were selected as nitrous oxide decomposition catalysts and loaded in the $Al_2O_3$ support using an impregnation method. The nitrous oxide conversions as a variation of GHSV and reaction temperature were measured in a tubular reactor. At the low GHSV and high temperature, the conversion was increased, and Ru/$Al_2O_3$ catalyst showed better performance than Pt/$Al_2O_3$ catalyst.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.531-535
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• 2013

The effect of heat-treatment temperature on the activity of catalysts was studied by investigating $N_2O$ decomposition reaction in Fe ion-supported BEA Zeolite. As a result of $N_2O$ decomposition reaction experiment, $N_2O$ decomposition activity significantly decreased as heat-treatment temperature of Fe/BEA catalyst increased. the shape and size of the particles of Fe/BEA catalyst following the rise of heat-treatment temperature did not display a significant change. But following the rise of the heat-treatment temperature, its surface area was significantly reduced. Also it was confirmed that as the heat-treatment temperature rose, the crystallization of ${\beta}$ structure was greatly reduced. And as heat-treatment temperature rose, while SiO structure either increased or did not exhibit much change, the structure of Fe bonded with lattice structure was speculated to decrease. From the stated results, it was concluded that the increase of heat-treatment temperature became the cause of the declined activity of catalysts by destruction of its ${\beta}$ structure of bonding aluminium and Fe atoms.

• Carbon letters
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• v.5 no.4
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• pp.180-185
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• 2004

Thermolysis of $Cu(NO_3)_2{\cdot}3H_2O$ impregnated activated carbon fiber (ACF) was studied by means of XRD analysis to obtain Cu-impregnated ACF. $Cu(NO_3)_2{\cdot}3H_2O$ was converted into $Cu_2O$ around $230^{\circ}C$. The $Cu_2O$ was reduced to Cu at $400^{\circ}C$, resulting in ACF-C(Cu). Some Cu particles have a tendency to aggregate through the heat treatment, resulting in the ununiform distribution in ACF. Catalytic decomposition of NO gas has been performed by Cu-impregnated ACF in a column reactor at $400^{\circ}C$. Initial NO concentration was 1300 ppm diluted in helium gas. NO gas was effectively decomposed by 5~10 wt% Cu-impregnated ACF at $400^{\circ}C$. The concentration of NO was maintained less than 200 ppm for 6 hours in this system. The ACF-C(Cu) deoxidized NO to $N_2$ and was reduced to ACF-$C(Cu_2O)$ in the initial stage. The ACF-$C(Cu_2O)$ also deoxidized NO to $N_2$ and reduced to ACF-C(CuO). This ACF-C(CuO) was converted again into ACF-C(Cu) by heating. There was no consumption of ACF in mass during thermolysis and catalytic decomposition of NO to $N_2$ by copper. The catalytic decomposition was accelerated with increase of the reaction temperature.

• Journal of the Korean Ceramic Society
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• v.37 no.10
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• pp.962-967
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• 2000

산소 결핍 페라이트 (oxygen deficient ferrites, ODF) MF $e_2$ $O_{4-}$$\delta$/는 약 30$0^{\circ}C$의 낮은 온도에서 온실가스중 하나인 $CO_2$를 C와 $O_2$로 분해시킨다. 본 연구에서는 $CO_2$분해 촉매로서 3원계 초미세 페라이트 N $i_{x}$Z $n_{1-x}$F $e_2$ $O_4$와 N $i_{x}$ $Co_{1-x}$F $e_2$ $O_4$를 수열합성법과 공침법 등의 습식 합성법으로 각각 합성하여 이들 분말의 특성과 $CO_2$분해 특성을 고찰하였다. 페라이트의 XRD 결과, 결정구조는 모두 전형적인 스피넬 구조로 동일하게 나타났다. BET 비표면적은 수열합성법으로 제조한 3원계 페라이트의 경우 110$m^2$/g 이상으로 공침법으로 제조한 페라이트보다 비교적 큰 값을 나타냈고 분말 입자크기 또한 약 10nm의 매우 미세한 분말을 얻을 수 있었다. 3원계 산소 결핍 페라이트의 $CO_2$분해 효율은 공침법으로 합성한 것보다 수열합성법으로 합성한 것이 더 우수하게 나타났으며, N $i_{x}$ $Co_{1-x}$F $e_2$ $O_{4-}$$\delta$/보다 N $i_{x}$Z $n_{1-x}$F $e_2$ $O_{4-}$$\delta$/가 우수한 것으로 나타났다.

• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.76-80
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• 2007

Three nano-sized Fe-N particle samples synthesized by Chemical Vapor Condensation (CVC) were analyzed using $M\"{o}ssbauer$ spectroscopy, XRD and BET. The synthesized nanoparticles consisted of ${\epsilon}-Fe_{2.12}N,\;{\gamma}'-Fe_4N,\;{\alpha}-Fe\;and\;{\gamma}-Fe.\;{\gamma}'-Fe_4N$ was mainly formed at the low decomposition temperature. With increasing decomposition temperature, the phase was changed to ${\gamma}-Fe$ via ${\epsilon}-Fe_{2.12}N$. For synthesizing Fe-N phases, this study implies that the low decomposition temperature is better than high temperature during Chemical Vapor Condensation.

• Journal of Hydrogen and New Energy
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• v.21 no.4
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• pp.278-285
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• 2010

The Sulfur-Iodine (SI) thermochemical hydrogen production process of a closed cycle consists of three sections, which are so called the Bunsen reaction section, the $H_2SO_4$ decomposition section and the HI decomposition section. To identify the role of oxygen that can be supplied to the Bunsen reaction section via the $H_2SO_4$ decomposition section, Bunsen reactions with a $SO_2,\;SO_2-O_2$ mixture and $SO_2-N_2$ mixture as feed gases were carried out using a stirred reactor in the presence of $I_2/H_2O$ mixture. As the results, the amounts of $I_2$ unreacted under the feed of mixture gases were higher than those under the feed of $SO_2$ gas only, and the amount of HI produced was relatively decreased. The results of Bunsen reaction using $SO_2-O_2$ mixture were similar to those using $SO_2-N_2$ mixture. It may be concluded that an oxygen in $SO_2-O_2$ mixture has a role as a carrier gas like a nitrogen in $SO_2-N_2$ mixture. The effects of oxygen were decreased with increasing temperature and decreasing oxygen content in $SO_2-O_2$ mixture.