• 공업화학
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• 제2권2호
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• pp.138-146
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• 1991

실리카-알루미나에 담지된 팔라듐 촉매를 제조하여 아크로레인과 암모니아로부터 피리딘과 ${\beta}$-피콜린의 합성반응에 사용하였다. 시간이 경과함에 따라 촉매표면에 생성된 침적물에 의하여 촉매의 활성이 크게 감소하였다. TPR 실험 결과 이 침적물은 아크로레인과 암모니아의 축합 중합에 의하여 생성됨을 알 수 있었다. 전화율과 피리딘 및 ${\beta}$-피콜린의 생성속도는 아크로레인의 분압이 증가할수록 감소하였다. 침적물의 양과 촉매재생 온도는 아크로레인의 분압에 따라 증가하였으나 암모니아의 분압에는 큰 영향을 받지 않았다.

• 신재생에너지
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• 제9권1호
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• pp.51-59
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• 2013

Tantalum carbide crystallites which is to be used for $H_2$ fuel cell has been synthesized via a temperature-programmed reduction of $Ta_2O_5$ with pure $CH_4$. The resultant Ta carbide crystallites prepared using two different heating rates and space velocity exhibit the different surface areas. The $O_2$ uptake has a linear relation with surface area, corresponding to an oxygen capacity of $1.36{\times}10^{13}\;O\;cm^{-2}$. Tantalum carbide crystallites are very active for hydrogen production form ammonia decomposition reaction. Tantalum carbides are as much as two orders of magnitude more active than Pt/C catalyst (Engelhard). The highest activity has been observed at a ratio of $C_1/Ta^{{\delta}+}=0.85$, suggesting the presence of electron transfer between metals and carbon in metal carbides.

• Applied Science and Convergence Technology
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• 제23권1호
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• pp.44-47
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• 2014

In this study, we investigated the basic properties of N-doped ethylcyclohexene plasma polymer thin films that deposited by radio frequency (13.56 MHz) plasma-enhanced chemical vapor deposition (PECVD) method with controlled ammonia flow rate. Ethylcyclohexene was used as organic precursor with hydrogen gas as the precursor bubbler gas. Additionally, ammonia ($NH_3$) gas was used as nitrogen dopant. The as-grown polymerized thin films were analyzed using ellipsometry, Fourier-transform infrared [FT-IR] spectroscopy, UV-Visible spectroscopy, and water contact angle measurement. We found that with increasing plasma power, film thickness is gradually increased while optical transmittance is drastically decreased. However, under the same plasma condition, water contact angle is decreased with increasing $NH_3$ flow rate. The FT-IR spectra showed that the N-doped ethylcyclohexene plasma polymer films were completely fragmented and polymerized from ethylcyclohexane.

• Archives of Pharmacal Research
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• 제13권4호
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• pp.306-309
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• 1990

The synthesis of 5-hyterocyclimethyl-2'-deoxyuridines (4a-f) has been accomplished by displacement reaction of 5-(bromomethyl)-3', 5'-di-O-acetyl-2'-deoxyuridine with heterocyclic compounds, followed by removal of acetyl protecting group with methanolic ammonia. The compoudns synthesized were evaluated the inhibitory effects on L1210 cell probiferation and antiviral activities against Herpes simplex virus type 1 (HSV-1) None of the compounds exhibited sufficient biological activities.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.1-7
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• 2020

The synthesis and catalytic activities over vanadium carbides were examined for ammonia decomposition reaction to produce the hydrogen. In particular, the comparison of vanadium nitrides were made on the ammonia decomposition reaction. The experimental data exhibited that BET surface areas ranged from 5.2 ㎡/g to 25.6 ㎡/g and oxygen uptake values varied from 3.8 μmol/g to 31.3 μmol/g. It is general that vanadium carbides (VC) were observed to be superior to vanadium nitrides for ammonia decomposition reaction. The primary reason for these differences were thought to be related to the extent of electronegativity between these materials. Most of vanadium carbide crystallites were exceeded by Pt/C crystallite. We assumed that the activities for vanadium carbide crystallites (VC) were comparable to or even higher than that determined for the Pt/C crystallite.

• 한국결정성장학회지
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• 제19권3호
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• pp.125-129
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• 2009

The preparation and characterization of niobium carbide crystallites were investigated in this study, and in particular, the effect of preparation conditions were studied on the synthesis of niobium carbides crystallites. For this purpose, various characterization techniques including x-ray diffraction, BET surface area, and oxygen uptake measurements were employed to characterize the synthesized niobium carbide crystallites. The niobium carbide crystallites were prepared using niobium oxide and methane gas or methane-hydrogen mixture. Using x-ray diffraction a lattice parameter of $4.45{\AA}$ and a crystallite size ranging from $52{\AA}$ to $580{\AA}$ was found. BET surface areas ranged from $3.2\;m^2/g$ to $16.6\;m^2/g$ and oxygen uptake values varied from $0.5{\mu}mol/g$ to $6.1{\mu}mol/g$. It was observed that niobium carbide crystallites were active for ammonia decomposition reaction. While the BET surface area increased with increasing the oxygen uptake, the conversion of ammonia decomposition reaction decreased. These results indicated that the ammonia decomposition over these materials was considered to be structure-sensitive.

• 상하수도학회지
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• 제21권3호
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• pp.295-303
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• 2007

Nitrogen compounds in municipal wastewater can be divided into biodegradable and nonbiodegradable fractions with biodegradability. Biodegradable nitrogen compounds can be removed through biological nitrification and denitrification processes, and nonbiodegradable nitrogen compounds affect the effluent quality of biological nutrient removal processes. The amount of nitrifiable nitrogen compounds, which are the sum of ammonia and biodegradable organic nitrogen, has been estimated by respirometry. Respirometry shows good estimation of the concentration of nitrifiable nitrogen when a synthetic sample of ammonium chloride is dosed. The estimated concentration of nitrifiable nitrogen compounds in municipal wastewater is close to ammonia concentration in municipal wastewater, but it is lower than that for the synthetic sample. If nitrogen assimilated into cell synthesis of nitrifiers and heterotrophs is considered, the total amounts of nitrifiable nitrogen compounds, which are nitrified and assimilated, could be more accurately estimated. The concentration of nitrifiable nitrogen compounds, which are biodegradable, is about 31 mg N/l, and this is 119% of ammonia and 94% of total nitrogen. Ammonia, nitrate, biodegradable organic nitrogen, and nonbiodegradable nitrogen are about 79%, 1%, 15%, and 5% of the total nitrogen in municipal wastewater, respectively.

• 한국재료학회지
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• 제11권8호
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• pp.697-702
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• 2001

열화학 기상 증착법을 이용하여 암모니아 처리에 따른 촉매 금속의 표면형태와 탄소 나노튜브의 성장을 조사하였다. 암모니아 처리의 열화학 과정의 조절에 의해 고르게 분산된 수직 성장된 탄소 나노튜브를 얻었다. 탄소 나노튜브 합성시 암모니아처리는 수직성장 및 고밀도 성장에 중요한 과정으로 그 역할에 대해 알아보았다. 고밀도의 수직 배향된 탄소나노튜브의 구조와 형태는 주사전자 현미경과 투과전자 현미경, 라만을 이용하여 관찰하였다.

• 한국세라믹학회지
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• 제51권3호
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• pp.201-207
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• 2014

High-purity aluminum nitride nanopowders were synthesized using an RF induction thermal plasma instrument. Ammonia and nitrogen gases were used as sheath gas to control the reactor atmosphere. Synthesized AlN nanopowders were characterized by XRD, SEM, TEM, EDS, BET, FTIR, and N-O analyses. It was possible to synthesize high-purity AlN nanoparticles through control of the ammonia gas flow rate. However, additional process parameters such as plasma power and reactor pressure had to be controlled for the production of high-purity AlN nanopowders using nitrogen gas.

• 환경위생공학
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• 제12권2호
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• pp.1-12
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• 1997

This research aims to develop biofilm process for the nutrient removal of piggery wastewater. The developed process is the four stage anoxic-oxic biofilm process with recirculation of the final effluent. In summery, the results are as follows: 1. Nitrification in the piggery wastewater built up nitrite because of the high strength ammonia nitrogen. The nitrification of nitrobacter by free ammonia was inhibited in the total ammonia nitrogen loading rate with more than 0.2 kgNH$_{3}$-N/m$^{3}$·d. 2. The maximal total ammonia nitrogen removal rate was obtained at 22$\circ $C and without being affected by the loading rate. But total oxidized nitrogen production rate was largely affected by loading rate. 3. Autooxidation by the organic limit was a cause of the phosphorus release in the aerobic biofilm process. But the phosphorus removal rate was 90 percent less than the influent phosphorus volumetric loading rate of above 0.1 kgP/m$^{3}$·d. Therefore, the phosphorus removal necessarily accompanied the influent loading rate. 4. On the anoxic-oxic BF process, the total average COD mass balance was approximately 67.6 percent. Under this condition, the COD mass removal showed that the cell synthesis and metabolism in aerobic reactor was 42.8 percent and that the denitrification in anoxic reactor was 10.7 percent, respectively.