• Membrane Journal
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• v.17 no.2
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• pp.134-139
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• 2007

Experimental and numerical analysis were performed for separation of carbon dioxide from carbon dioxide and nitrogen gas mixture using a polyethersulfone hollow fiber membrane. The experimental results were compared with those obtained at the same operating condition by the numerical analysis. It was observed that there was a big difference between the experimental results and those by a numerical analysis where the permeance of carbon dioxide and its ideal selectivity over nitrogen were obtained from the pure gas permeation. Therefore, the permeance of carbon dioxide and its selectivity were obtained from the separation experimental results using the numerical analysis as a function of the mole fraction of carbon dioxide, the feed pressure and the permeate pressure in the gas mixture. The results of the numerical analysis using the selectivity obtained from the gas mixture were in good agreement with those of the experimental.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.1
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• pp.1-7
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• 2022

Interest in hydrogen productions that do not emit carbon dioxide and can produce hydrogen at a low price is increasing. Reforming and electrolysis are widely used, but they have limitations, such as carbon dioxide problems and costs. The methane can be decomposed as hydrogen and solid carbon without carbon dioxide emission at high temperatures. In this research, the methane pyrolysis experiment was conducted at 1,200℃ and 1,400℃ in a ceramic tube. The composition of the produced gas was measured by gas chromatography before carbon blocked the tube. The methane conversion rate and hydrogen selectivity were calculated based on the results. The hydrogen selectivity was derived as 60% and 55% at the highest point at 1,200℃ and 1,400℃, respectively. The produced solid carbon was expected to be carbon black and was analyzed using scanning electron microscope.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.3
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• pp.287-296
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• 2013

To decompose carbon dioxide, which is a representative greenhouse gas, a plasma torch was designed and manufactured. To examine the characteristics of carbon dioxide decomposition via plasma discharge, a case wherein pure carbon dioxide was supplied and a case wherein methane and/or $TiCl_4$ were injected as additives were investigated and compared. The carbon dioxide and methane conversion rate, energy decomposition efficiency, produced gas concentration, carbon monoxide and hydrogen selectivity, carbon-black and $TiO_2$ were also investigated. The maximum carbon dioxide conversion rate was 28.9% when pure carbon dioxide was supplied; 44.6% when $TiCl_4$ was injected as am additive; and 100% percent when methane was injected as an additive. Therefore, this could be explained that the methane injection showed the highest carbon dioxide decomposition. Furthermore, the carbon-black and $TiO_2$ were compared with each commercial materials through XRD and SEM. It was found that the carbon-black that was produced in this study is similar for commercial materials. It was found that the $TiO_2$ that was produced in this study is suitable for photocatalyst and pigment because it has mixed anataze and rutile.

• Membrane Journal
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• v.25 no.3
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• pp.248-255
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• 2015

Aminated polyetherimide membrane synthesized in the laboratory according to amine ratio was used for measurement of gas permeability, diffusivity, and solubility about carbon dioxide, nitrogen, methane, oxygen, and sulfur dioxide with Time-lag method at room temperature. Generally, gas permeability is totally decreased because the more amination rate reacted to the main chain of amine groups, the more intermolecular space became narrow. However, gas permeability of sulfur dioxide was increased due to combination of sulfur dioxide and amine groups have acid and base properties respectively. Diffusivity and solubility of dry gas are totally decreased excluding sulfur dioxide as increasing amination rate. In case of sulfur dioxide, however, diffusivity as well as solubility was increased as increasing amination rate. Selectivity of carbon dioxide/nitrogen showed 60 when amination rate was 3. In case of humid gas, gas permeability of carbon dioxide was 70 barrer when relative humidity showed 100, and selectivity with nitrogen approximately showed 18.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1743-1748
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• 2005

This work presents that carbon dioxide, which is a main contributor to the global warming effect, could be utilized as a selective oxidant in the oxidative dehydrogenation of ethylbenzene. The dehydrogenation of ethylbenzene over alumina-supported vanadium-antimony oxide catalyst has been studied under different atmospheres such as inert nitrogen, steam, oxygen or carbon dioxide as diluent or oxidant. Among them, the addition of carbon dioxide gave the highest styrene yield (up to 82%) and styrene selectivity (up to 97%) along with stable activity. Carbon dioxide could play a beneficial role of a selective oxidant in the improvement of the catalytic behavior through the oxidative pathway.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.131-141
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• 2009

The conversion of carbon dioxide to value-added compounds has been attracted to solve the environmental problems due to the climate change caused by greenhouse effect in addition to recycle the abundant and renewable carbon source. For utilizing carbon dioxide to useful compounds, the development of catalysts and optimization of experimental conditions are indispensable since carbon dioxide is the most stable one among carbon compounds and the a certain amount of energy is required for the carbon dioxide conversion. The technologies developed for the electrochemical carbon dioxide conversion were reviewed in terms of electrocatalyst which can be electrode material, inorganic complex, and enzyme. This field should be developed further since no good catalyst having selectivity, efficiency, and stability all together.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.576-583
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• 2023

This study investigated the possibility of new adsorbent materials made from pig bone-based biomass. To this end, the properties of pig bone-based activated carbon (PAC) prepared from animal biomass were investigated, and its carbon dioxide adsorption performance was examined. KOH was used as the activation agent, and the specific surface area increased with increasing activation temperature, and the adsorption efficiency of carbon dioxide also increased. The sample activated at 800 ℃ exhibited the largest specific surface area of 1208.7 m²/g and the highest CO₂ adsorption efficiency of 3.33 mmol/g at 273 K, 1 bar. However, the specific surface area and the CO₂ adsorption efficiency decreased at activation temperatures above 900 ℃ due to crystallinity changes and overactivation. On the other hand, when the selectivity was calculated using the ideal adsorption solution theory, PAC-900 samples at 273 K and below 0.8 bar showed the best selectivity. These results suggest that the high selectivity of carbon dioxide/nitrogen adsorption at 273 K is due to the carbon dioxide adsorption capacity of hydroxyapatite formed by the decomposition of carbonate when pig bone is activated at 900 ℃ and its crystallinity.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.2
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• pp.97-104
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• 2007

In different approaches were extracted from evening primrose seed by supercritical fluids carbon dioxide and for comparison with hexane as solvent. The extracts have been analyzed qualitatively and quantitatively to evaluate yield and selectivity of ${\gamma}$-linolenic acid. The yields extracts with supercritical fluids carbon dioxide were higher than those with hexane. When this process produces commercially, will get a many economic profit.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.5
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• pp.655-662
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• 2004

An adsorption process to recover the pure $CH_4\;and\;CO_2$ from its mixture was examined. In this study, activated carbon fibers were used as a selective adsorbent. The activated carbon fibers has 78~94% micropore volume and 10.5~20.3${\AA}$ narrow pore size, and showed high adsorption rate and the good selectivity for $CO_2$ under the ambient pressure. The ACF with high surface area showed short mass transfer zone and long breakthrough time and, its adsorption capacity depended on the microporosity. Compared with single component adsorption, the amount adsorbed $CO_2$ on ACF increased by the roll-up of $CH_4$ in mixed gases. The adsorption selectivity increased as now rate and $CO_2$ concentration of mixed gases increased, showing 5.2 selectivity for 75% $CO_2$ concentration.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05b
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• pp.147-152
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• 2004

Gas separation membrane technology is useful for a variety of applications [1, 2]. such as hydrogen recovery from reactor purge gas, nitrogen and oxygen enrichment, water vapor removal from air, stripping of carbon dioxide from natural gas. etc. Although membrane separations are attractive because of low energy costs and simple operation, low permeabilities and/or selectivity often limit membrane applications [3, 4].(omitted)