• Journal of the Korean Chemical Society
• /
• v.37 no.12
• /
• pp.1019-1024
• /
• 1993

The coadsorption of carbon monoxide and oxygen on polycrystalline nickel surface has been studied using XPS at the room temperaure. The adsorption of CO on the nickel surface precovered partially with oxygen is found to take place by the following steps: The CO molecules react with the preadsorbed oxygen atoms to liberate $CO_2$ gas at the initial stage of low CO exposures, and they are coadsorbed gradually with the increasing CO exposures. The extent of coadsorption at the higher CO exposures is found to decrease with the increasing degree of oxygen preadsorption. This finding is explained in terms of the reduced adsorption site for CO as a consequence of oxygen preadsorption. The CO molecules preadsorbed on the nickel surface inhibited the adsorption of $O_2$ molecules. The increase of oxygen exposure led to the dissociation of preadsorbed CO, and the NiO layers were formed concurrently. The dissociation was rendered to arise from an oxygen-to-CO energy transfer.

• Clean Technology
• /
• v.19 no.4
• /
• pp.370-378
• /
• 2013

This review has shown the capability of MOFs and ZIFs materials to adsorb $CO_2$ under typical PSA temperatures and pressures. The usual operating conditions are adsorption temperatures of $15{\sim}40^{\circ}C$ and adsorption pressures of 4~6 bar based on numerous PSA processes which are widely employed in gases industry for adsorptive separation of $CO_2$. The extent of $CO_2$ adsorption on the microporous materials depends on the metal species and organic linkers existing in the frameworks. The pore size and the surface area, and the process variables are the key parameters to be associated with the efficiency of the adsorbents, particularly adsorption pressures if other variables are comparable each other. The MOFs and ZIFs materials require high pressures greater than 15 bar to yield significant $CO_2$ uptakes. They possess a $CO_2$ adsorption capacity which is very similar to or less than that of conventional benchmark adsorbents such as zeolites and activated carbons. Consequently, those materials have been much less cost-effective for adsorptive $CO_2$ separation to date because of very high production price and the absence of commercially-proven PSA processes using such new adsorbents.

• Journal of the Korean Magnetics Society
• /
• v.16 no.1
• /
• pp.92-97
• /
• 2006

A study of the adsorption site of CO in the Ni(111)$(2\times2)$-O/CO coadsorbed phase over different sample preparation temperatures revealed that the atop site is favoured. The Ni-C spacing is given by $1.77\pm0.01\;{\AA}$. A study of the adsorption site of Co in the Ni(111)$(2\times2)$-O/CO coadsorbed phase over different sample preparation temperatures revealed that the atop site is favoured. The Ni-C spacing is given by $1.77\pm0.01\;{\AA}$. The data from the sample prepared at 265 K showed atop sites, which is well consistent with vibrational spectroscopy, whilst the data from the low temperature preparation appears the mixture of atop and hop $(35\%)$. The occupation of hop hollow sites is probably due to an incorrect pre-coverage of atomic oxygen (different from 0.25ml). Similar observation of site mixture also found in recent high resolution XPS measurements using C 1s and O 1s chemical shifts.

• Clean Technology
• /
• v.7 no.4
• /
• pp.265-272
• /
• 2001

본 연구는 지구 온난화 현상의 주원인이 되는 $CO_2$ 를 화력발전소 연도가스로부터 분리 회수하기 위한 PSA 공정 개발용 기초자료를 습득하기 위하여 실시하였다. 연도가스와 유사한 조건하에서 국내에서 제조된 활성탄을 이용하여 이산화탄소 및 밸런스를 이루고 있는 질소 가스의 흡착평형 및 흡착속도 실험을 실시하였으며, 분석을 위하여 자체 제작한 장치(부피측정법) 및 TGA 장치를 각각 사용하였다. 이 연구에서 획득한 흡착등온선으로부터 사용된 흡착제가 이산화탄소의 분리에 적절한지 판단할 수 있었다. 또한, TGA에 의해 측정된 흡착속도 자료는 향후 사용될 흡착탑의 파과곡선 예측에 사용될 수 있다. 연구결과로부터 다음과 같은 사실을 알 수 있었다. 첫째, 낮은 흡착온도 일수록 흡착량이 많고 빠른 흡착속도를 나타내었다. 둘째, 압력이 높아질수록 흡착량은 증가하였다. 셋째, SGT활성탄이 SGA-100 및 SGP-100활성탄 보다 다소 많은 흡착량과 빠른 흡착속도를 보였다.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.06a
• /
• pp.485-495
• /
• 2005

This study was conducted to investigate sorption and desorption behaviors of radionuclides (Cobalt and Strontium) in natural soil. Sorption kinetics and isotherms were analyzed to predict sorption behaviors of radionuclides in natural soil and the experimental data were fitted to several sorption models. Desorption experiments were also performed with or without CMCD at constant pH and ion strength conditions. The results showed that $Sr^{2+}$ was more strongly sorbed than $Co^{2+}$ in natural soil. Both $Co^{2+}$ and $Sr^{2+}$ followed a pseudo-second order kinetics and Sips model. The desorption-resistance of $Co^{2+}$ and $Sr^{2+}$ was estimated using a natural surfactant Carboxymethyl-${\beta}$-cyclodextrin(CMCD) or non-desorbing fraction. Desorption of radionuclides was partially irreversible and $Sr^{2+}$ was more resistant than $Co^{2+}$ Addition of CMCD facilitated desorption of $Co^{2+}$ and $Sr^{2+}$ from soil.

• Proceedings of the KAIS Fall Conference
• /
• 2008.11a
• /
• pp.411-414
• /
• 2008

본 논문에서는 $CO_2$ 분리용 활성탄의 표면분석 및 흡착속도를 비교하였다. TGA 방법에 의한 흡착속도 데이터를 획득함으로써 분리장치 설계를 위한 기초자료를 획득하였고, 흡착온도에 따른 결과는 흡착온도가 낮을수록, 흡착량이 증가하고 흡착속도 또한 더 빠름을 알 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.299.1-299.1
• /
• 2013

넓은 표면적을 갖는 탄소나노튜브(CNT)는 기체 분자의 흡착 성능이 기존의 다른 흡착제에 비해 우수한 것으로 알려져 있으나, CNT의 물리/화학적 성질은 튜브의 직경과 기하 구조에 의해 큰 차이를 나타내며 정제가 매우 까다롭다는 단점을 가지고 있다. CNT와 외형적으로 매우 흡사한 질화붕소 나노튜브(BNNT)의 경우, 구조와 직경에 상관없이 열적, 화학적 안정성이 우수하여 $CO_2$를 비롯한 다른 공해 물질들의 제거제나 흡착제로서 응용 가능성이 매우 높다. 본 연구진은, BN-결함을 도입한 BNNT 벽면에서의 $CO_2$ 흡착 반응과 $CO_2$를 에너지 물질인 HCOOH와 $H_2CO_3$로 전환하는 반응에 대한 양자화학 이론 계산 연구를 수행하였다. 그 결과, $CO_2$에 대한 $B_N$-BNNT 흡착 성능이 튜브의 직경에 상관없이 매우 우수하였고, $B_N$-BNNT 벽면상에 흡착된 $CO_2$가 물 분자와 반응할 경우 HCOOH와 $H_2CO_3$로의 전환반응이 효과적으로 진행되었다. 이러한 이론 계산 연구 결과는 BN-BNNT가 $CO_2$ 흡착제 및 에너지 전환 촉매로의 응용 가능성을 훌륭히 제시하고 있다.

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.5
• /
• pp.307-311
• /
• 2013

Direct Air Capture (DAC) technology using reusable energy is a plausible process to capture $CO_2$ from non-point sources. In this paper, adsorption and desorption were repeatedly tested using low concentration $CO_2$. Three types of adsorbents were examined in cyclic $CO_2$ adsorption and thermal regeneration. Adsorption capacities of zeolite 5A, zeolite 13X and activated carbon were 21 mg/g, 12 mg/g and 6 mg/g, respectively. Zeolite 5A shows the highest adsorption capacities after cyclic thermal regeneration.

• Applied Chemistry for Engineering
• /
• v.5 no.2
• /
• pp.189-198
• /
• 1994

The adsorptive behaviors of carbon monoxide and methanol over $V_2O_5$catalyst were studied by means of thermal desorptlon spectroscopy (TDS) under ultrahigh vacuum conditions. Carbon monoxide adsorbed on oxygen-deficient V sites as well as on V=O groups of the $V_2O_5$ surface. CO adsorbed on the V sites desorbed at 380 K while CO adsorbed on the V=O groups formed carbonate species with surface oxygen of $V_2O_5$ and desorbed as $CO_2$ resulting in the reduction of the surface of she $V_2O_5$catalyst. The amount of CO adsorbed in the form of carbonate species increased by both the pre- and post-adsorbed oxygen. The adsorptive behavior of methanol over the catalyst was studied by thermal desorption experiments of $CH_3OH$, HCHO, CO, and $H_2$ upon methanol adsorption at 298 K. The results showed that methanol was adsorbed dissociatively on the $V_2O_5$catalyst as methoxy and hydroxyl groups at 298K.

• Korean Chemical Engineering Research
• /
• v.54 no.6
• /
• pp.838-846
• /
• 2016

Most of combustion processess used in industries require recovering or removing flue gas components. Recently a new MBA (moving bed adsorption) process for recovering $CO_2$ using zeolite 13X was developed. In this study, adsorption experiments for carbon dioxide, nitrogen, sulfur dioxide, and water vapor on zeolite 13X were carried out. Adsorption equilibrium and adsorption rate into solid particle were investigated. Langmuir, Toth, and Freundlich isotherm parameters were calculated from the experiment data at various temperatures. Experimental results were consistent with the theoretically predicted values. Also $CO_2$ adsorption amount was measured under the conditions with impurities such as $SO_2$ and $H_2O$. Binary adsorption data were well fitted to the extended Langmuir isotherm using parameters obtained from pure component experiment. However, $H_2O$ impurity less than, roughly, ${\sim}10^{-5}H_2O\;mol/g$ zeolite 13X enhanced slightly $CO_2$ adsorption. Spherical particle diffusion model well described experimentally measured adsorption rate. Diffusion coefficients and activation energies of $CO_2$, $SO_2$, $N_2$, $H_2O$ were obtained. Diffusion coefficients of $CO_2$ and $SO_2$ decreased with small amount of preadsorbed impurity. Parameter values from this study will be helpful to design of real commercial adsorption process.