• Clean Technology
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• v.28 no.3
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• pp.218-226
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• 2022

As a result of the recent social transformation towards a hydrogen economy and carbon-neutrality, the demands for hydrogen energy have been increasing rapidly worldwide. As such, eco-friendly hydrogen production technologies that do not produce carbon dioxide (CO₂) emissions are being focused on. Among them, ammonia (NH₃) is an economical hydrogen carrier that can easily produce hydrogen (H₂). In this study, Ru/Al₂O₃ catalyst coated onmetallic monolith for hydrogen production from ammonia was prepared by a dip-coating method using a catalyst slurry mixture composed of Ru/Al₂O₃ catalyst, inorganic binder (alumina sol) and organic binder (methyl cellulose). At the optimized 1:1:0.1 weight ratio of catalyst/inorganic binder/organic binder, the amount of catalyst coated on the metallic monolith after one cycle coating was about 61.6 g L^-1. The uniform thickness (about 42 ㎛) and crystal structure of the catalyst coated on the metallic monolith surface were confirmed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Also, a numerical optimization regression equation for NH3 conversion according to the independent variables of reaction temperature (400-600 ℃) and gas hourly space velocity (1,000-5,000 h^-1) was calculated by response surface methodology (RSM). This model indicated a determination coefficient (R²) of 0.991 and had statistically significant predictors. This regression model could contribute to the commercial process design of hydrogen production by ammonia decomposition.

• Membrane Journal
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• v.28 no.5
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• pp.297-306
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• 2018

This review focused carbon-free hydrogen productions from ammonia decomposition including inorganic membranes, catalysts and the presently studied reactor configurations. It also contains general information about hydrogen productions from hydrocarbons as hydrogen carriers. A Pd-based membrane (e.g. a porous ceramic or porous metallic support with a thin selective layer of Pd alloy) shows its efficiency to produce the high purity hydrogen. Ru-based catalysts consisted of Ru, support, and promoter are the efficient catalysts for ammonia decomposition. Packed bed membrane reactor (PBMR), Fluidized bed membrane reactor (FBMR), and membrane micro-reactor have been studied mainly for the optimization and the improvement of mass transfer limitation. Various types of reactors, which contain various combinations of hydrogen-selective membranes (i.e. Pd-based membranes) and catalysts (i.e. Ru-based catalysts) including catalytic membrane reactor, have been studied for carbon-free hydrogen production to achieve high ammonia conversion and high hydrogen flux and purity.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.18-24
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• 2012

Lignocellulose is difficult to hydrolyze due to the presence of lignin and the technology developed for cellulose fermentation to ethanol is not yet economically viable. However, recent advances in the extremely new field of biotechnology for the ethanol production are making it possible to use of Agriculture residual biomass, e.q., Barley straw, because of their several superior aspects as Agriculture residual biomass; low lignin, high contents of carbohydrates. Barley straw consists of 39.78% cellulose (glucose), 22.56% hemicelluloses and 19.27% lignin. Pretreatment of barley straw using NaOH pretreatment solutions concentration with 2%, temperature $85^{\circ}C$ and reaction times 1 hr were investigates. $NH_4OH$ pretreatment condition was solutions concentration with 15%, temperature $60^{\circ}C$, and reaction times 24hr were investigates. Furthermore, enzymatic saccharification using cellulose at $50^{\circ}C$, pH 4.8, 180 rpm for conversion of cellulose contained in barley straw to monomeric sugar. The pretreatment of barley straw using NaOH and $NH_4OH$ can significantly improve enzymatic saccharification of barley straw by extract more lignin and increasing its accessibility to hydrolytic enzymes. The result showed NaOH pretreatment extracted yield of lignin was 24.15%. $NH_4OH$ pretreatment extracted yield of lignin was 29.09%. Shaccharification of barley straw pretreatment by NaOH for 72hr and pH 4.8 result in maximum glucose concentration 15.39g/L (58.40%) and by $NH_4OH$ for 72hr and pH 4.8 result in maximum glucose concentration 16.01g/L (64.78%).

• Korean Journal of Soil Science and Fertilizer
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• v.13 no.1
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• pp.7-11
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• 1980

In order to learn about the volatilization of ammonia in relation to the amont of nitrogenous fertilizer, a laboratory experiment incubated between $35-40^{\circ}C$ for seven days, applying with 3.75mg N, 7.5mg N, and 11.25mg N in urea form, had been carried out. The result obtained are as follows : 1. As the amont of urea increases, the volatilization of ammonia enhanced. The enhancement of the volatilization of ammonia showed a close relationship with the pH raise of soil which is resulted from the formation of ammonia in soil. 2. Over liming decreased the volatilization of ammonia depressing the hydrolysis of urea and the ammonification of soil nitrogen. This tendency was far more pronounced when the pH of soil exceed 8.0.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.490-497
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• 2006

$V_{2}O_{5}$/$TiO_{2}$ catalyst can be deactivated by ammonium salts formed by $SO_{2}$ oxidation and unreacted ammonium in presence of $SO_{2}$ in flue gas. The deactivation of catalyst by $SO_{2}$ depends on the $SO_{2}$ oxidation to $SO_{3}$. The oxidation of $SO_{2}$ is weakly affected by oxygen concentration, and strongly by the amount of vanadium loaded onto titania supports. Because unreacted ammonia is one of elements to form the ammonium salts, it is important to control the mole ratio of $NH_{3}/NOx$ in SCR. Thus the experiments about $NH_{3}/NOx$ were carried out. The reason of low activity of catalyst deactivated by ammonium salts is the change of pore volume. And TPD (Temperature Programmed Decomposition) was performed to find the decomposition of ammonium bisulfate on deactivated catalyst.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.159-168
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• 2022

Catalytic activity in ammonia decomposition reaction was studied on Mo-Al nitride obtained through temperature programmed nitridation of calcined Mo-Al mixed oxide prepared by varying the MoO₃ quantity in the range of 10-50 wt%. N₂ sorption analysis, X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS) and H₂-temperature programmed reduction (H₂-TPR), and transmission electron microscopy (TEM) to investigate the physicochemical properties of the prepared catalyst were performed. After calcination at 600 ℃, the XRD of Mo-Al oxide showed γ-Al₂O₃ and Al₂(MoO₄)₃ phases, and the nitride after nitridation showed an amorphous form. The specific surface area after nitridation by topotactic transformation of MoO₃ to nitride was increased due to the formation of Mo nitride, and the Mo nitride was observed to be supported on γ-Al₂O₃. As for the catalytic activity in the ammonia decomposition reaction, 40 wt% MoO₃ showed the best activity, and as the nitridation time increases, the activity increased, and thus the activation energy decreased.

• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.360-365
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• 2014

Vapor-phase hydrogen peroxide(VPHP) has been used as a sterilant in the field of medical and pharmaceutical application due to low corrosive than chlorine contained sterilant. In addition, it is well known that VPHP is effective for decontamination of chemical warfare agents by adding ammonia gas. In this study, the decontamination efficiency was confirmed about CEPS, DFP and dimethoate as simulants of HD, GD and VX using VPHP respectively. For this purpose, VPHP generated from self configured device was injected into decontamination chamber and maintained for reaction time. After the decontamination, the residues are analyzed by GC/MS and decontamination efficiency was calculated. Through by-product for each simulants, the similarities in reaction mechanism of chemical warfare agents were confirmed. CEPS was completely decontaminated at 30% relative humidity within 60 min. By adding ammonia gas, DFP and dimethoate were completely decontaminated within 30 and 150 min respectively.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.704-711
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• 2010

Lignocellulose ($2^{nd}$ generation) is difficult to hydrolyze due to the presence of lignin and the technology developed for cellulose fermentation to ethanol is not yet economically viable. However, recent advances in the extremely new field of biotechnology for the ethanol production are making it possible to use of agriculture residuals and nonedible crops biomass, e.q., rice straw and miscanthus sinensis, because of their several superior aspects as agriculture residual and nonedible crops biomass; low lignin, high contents of carbohydrates. In this article, as the basic study of AP(Ammonia Percolation), the properties and the optium conditions of process were established, and then the overall efficiency of AP was investigated. The important independent variables for AP process were selected as ammonia concentration, reaction temperature, and reaction time. The percolation condition for maximizing the content of cellulose, the enzymatic digestibility, and the lignin removal was optimized using RSM(Response Surface Methodology). The determined optimum condition is ammonia concentration; 11.27%, reaction temperature; $157.75^{\circ}C$, and reaction time; 10.01 min. The satisfying results were obtained under this optimized condition, that is, the results are as follows: cellulose content(relative); 39.98%, lignin content(relative); 8.01%, and enzymatic digestibility; 85.89%.

• Journal of the Korea Organic Resources Recycling Association
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• v.6 no.2
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• pp.31-44
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• 1998

Mixtures of hog manure slurry and sawdust were composted by an intermittent aeration method to verify the performance evaluation of pilot-scale reactor vessels during composting high rate (decomposition) process. Instrumentation was designed to measure temperatures in compost, oxygen and carbon dioxide concentration, air flow rates, and ammonia gas emitted. It was found that ammonia concentration during composting high rate decreased more quickly to the allowable range of 34-40 ppm after 14days at near the optimal levels (II) than in the case of lower levels (I). The influence of the optimal levels (II) such as moisture content (55-65%), C/N ratio (20-40), pH (7-8) and temperature in compost (<$60^{\circ}C$) on the reduction of ammonia gas was considerable for commercial composting.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.981-987
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• 2000

Upflow anaerobic sludge blanket(UASB) reactor was operated for treating swine wastewater containing high ammonia nitrogen to assess their performance and toxicity of free ammonia concentration. In the reactor, chemical oxygen demand(COD) removed about 70% at $2.6kgCOD/m^3.day$ of organic loading rate(OLR) and 3 days of hydraulic retention time (HRT), while it was decreased when OLR and HRT was maintained $7kg\;COD/m^3.day$ and 2 days, respectively. Also UASB reactor was evaluated the activity of methane producing bacteria(MPB) according to change of free ammonia concentrations, MPB activity of applied sludge in the 500 and $1000mg-N/{\ell}$ of free ammonia concentration was inhibited by 4% and 40%, respectively. This clearly showed that free ammonia concentration less than $500mg-N/{\ell}$ showed no inhibition to MPB in anaerobic treatment of organics, UASB reactor was stabilized easily less than $1000mgVSS/{\ell}$ due to degradation of organic solids by the high activities of anaerobes.