• Applied Chemistry for Engineering
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• v.17 no.2
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• pp.201-209
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• 2006

Various desorption methods were investigated for an activated carbon and zeolite 13X packed bed after benzene adsorption. Desorption experiments using hot steam, purge gas, and evacuation were performed. As a result, the desorption with hot steam showed the best performance. Hot steam makes the temperature in the adsorption column increase and gives arise to the desorption. Drying process should be accompanied to increase the efficiency because steam vapor prevents the adsorption later. The vacuum desorption showed poor performance and it reveals that temperature swing operation is more effective than pressure swing operation. In the purge gas desorption, good performance was achieved using evacuation.

• Clean Technology
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• v.12 no.4
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• pp.217-223
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• 2006

The operating variables of a desorption step were experimentally investigated tor the cycle of the process made up of benzene adsorption, steam desorption, and drying step. The effect of adsorbent regeneration depending on existence and nonexistence of drying step was studied by breakthrough curves obtained in the adsorption step of the second cycle. The duration of drying step was determined by the experimental results. In case that the amount of nitrogen gas was fixed, the regeneration efficiency increased with the amount of steam. However, the effect of steam decreased as the amount of nitrogen increased. Therefore, it would be possible to predict the optimum amount of steam comparing the amount of nitrogen gas with amount of steam in economic view.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.173-182
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• 2020

In this study, amino acid salt absorbents were applied to remove and capture high concentrations of CO₂ in liquor factories and regeneration performance was confirmed. In order to evaluate the effective treatment of the desorption process, two methods(Hot plate and Steam) were compared at the laboratory scale. As a result, hot plate and Steam. Hot plate methods regeneration efficiency was about 10% and Steam methods was about 60%. The Steam-Tower condition was evaluated by installing a 100㎥/min flow rate scrubber absorption system in the liquor factory. As a result, it was established that the absorbent flow rate was below 4L/min and the steam temperature was above 160℃. Finally regeneration performance was confirmed as 85.5%.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.594-603
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• 2018

The effects of operating conditions such as benzene concentration, nitrogen flow rate, steam flow rate, and bed temperature on TSA process were experimentally investigated as a potential VOC removal technology using two kinds of beds packed with activated carbon and zeolite 13X. The TSA cycle studied was composed of the adsorption step, steam desorption step, and drying and cooling step. At 2% benzene concentration, the total adsorption amounts of zeolite 13X and activated carbon were 4.44 g and 3.65 g, respectively. Since the zeolite 13X has a larger packing density than that of the activated carbon, the larger benzene amount could be adsorbed in a single cycle. Increasing the water vapor flow rate to 75 g/hr at 2% benzene concentration reduced the desorption time from 1 hr to a maximum of 33 min. If the desorption time is shortened, the drying and cooling step period can be relatively increased. Accordingly, the steam removal and bed cooling could be sufficiently performed. The desorption amounts increased with the increase of the bed temperature. However, the energy consumption increased while the desorption amount was almost constant above $150^{\circ}C$. In the continuous cycle process, when the amount of remained benzene at the completion of the regeneration step increased, it might cause a decrease in the working capacity of the adsorbent. The continuous cycle process experiment for zeolite 13X showed that the amount of remained benzene at the end of regeneration step maintained a constant value after the fourth cycle.

• Journal of environmental and Sanitary engineering
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• v.11 no.2
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• pp.65-73
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• 1996

The objective of this study is to investigate the removal efficiency of volitile organic compounds in soil, and the mechanism of desorption by bench scale microwave heating, Silt soil used for experiment and was impregnated with toluene, tetrachloroethylene, o-xylene and p-dichlorobenzene and the microwave treatment was conducted in a modified domestic microwave oven : 2450MHz, 700W. According to the results of the research the removal efficiency was improved with increasing water contents and the soil temperature appeared to plateau period extending to 2-3minutes corresponds to the temperature a which steam distillation was expected. The value of removal rate constant (k) were calculated on dry and moisty silt soil, respectively, which showed linear with increasing microwave heating time. Therefore, addition of a certain amount of water to the contaminated soil can efficiently enhance the ability of the soil to absorb microwave energy and promote the evaporation of the volitile contaminants.

• Journal of the Korean Institute of Gas
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• v.9 no.4 s.29
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• pp.17-25
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• 2005

The dealuminated and alkali/alkaline-earth metal exchanged Y-zeolites were prepared as a catalyst. Elemental compositions and structures of the prepared catalysts were analyzed by the various spectroscopic techniques such as inductively coupled plasma-atomic emission spectroscopy(ICP-AES), X-ray fluorescence(XRF) and X-ray diffraction(XRD), and the desorption behaviors of adsorbed species on the catalyst surfaces were investigated via NO-TPD experiment. Comparing with the composition of the starting material of NaY zeolite, the magnitudes of Si/Al ratio in catalytic materials were increased after dealumination. The Si/Al ratio of catalytic materials after dealumination followed by Cs and Ba cation exchange were additionally decreased. Dealumination to catalysts induced a destruction of basic frame due to a detachment of aluminum, which results in reducing framework structure, while increasing non-framework structure. This phenomenon becomes more serious with increasing time of steam treatment and even more significant for the cation exchanged catalysts. In NO-TPD experiments, the desorption peaks of NO which indicates an activity point of catalysts shifted to the low temperature region after dealumination and cation exchange. The desorption peaks of the NO-TPD profiles taken after steam treatment also shifted to the low temperature region as the steam treatment time increased. In dealuminated and cation exchanged Y-zeolites, the catalytic activities were more influenced by exchanged cation and the formation of non-framework structure.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.67-74
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• 2001

In the manufacturing process of PCB , three kinds of VOCs such as aceton, methanol and 2-metoxyethanol are being used. In this study, adsorption characteristics of activated carbon fibers(ACFs) and active carbon were examined to temove these VOCs. The experimental results showed that ACF has better adsorption and regeneration efficiency than activated carbon. Phenolic-resin based ACF showed the highest adsorption capacity and the capacity was not decreased after repeated regeneration by steam. On the adsorption and desorption experiments for ternary components, preferential adsorption with roll-over phenomena was appeared. 2-Metoxyethanol was strong adsorbaste and it displaced adsorbed methanol and aceton.

• Carbon letters
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• v.8 no.1
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• pp.17-24
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• 2007

Microporous carbons with narrow pore size distribution have been successfully synthesized by using hydrolyzed and calcined silica as templates and phenol formaldehyde (pf) resin as carbon precursor. Phenol formaldehyde-silica micro composites were prepared by solution route. Subsesequently, silica templates were removed by HF leaching. Resulting carbons were steam activated. The porous carbons were characterized by nitrogen adsorption-desorption isotherm, SEM, FTIR analysis, iodine adsorption, thermogravimetry analysis, etc. Adsorption isotherms show that the porous carbon prepared from calcined silica as templates are microporous with 88% pores of size <2 nm porosity and are of type I isotherm, while porous carbon prepared by using hydrolyzed silica are microporous with 89% microporosity, shows hysteresis loop at high relative pressure indicating the presence of some mesoporosity in samples. The microporosity in porous carbon materials has a bearing on the nature of silica templates used for pore formation.

• Clean Technology
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• v.25 no.1
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• pp.33-39
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• 2019

A.C (activated carbon) is mainly used to remove VOCs (volatile organic compounds), however, it has many problems such as fire risk due to increasing of adsorbent surface temperature during VOCs ad/desorption, increased cost by frequent replacement cycles requirement and performance degradation when containing moisture. In order to solve these problems, many researches, hydrophobic zeolite adsorbents, have been reported. In this study, $NH_4{^+}Y$-zeolite was synthesized with Y-zeolite through steam treatment and acid treatment, which is one of the hydrophobic modification methods, to secure high surface area, thermal stability and humidity resistance. The Y, Y-550-HN, Y-600-HN and Y-650-HN had adsorption capacities of $23mg\;g^{-1}$, $38mg\;g^{-1}$, $77mg\;g^{-1}$, $61mg\;g^{-1}$. The change of Si/Al ratio, which is an index to confirm the degree of modification, was confirmed by XRF (X-ray fluorescence spectrometer) analysis. As a result, the adsorbtion performance was improved when Y-zeolite modified, and the Si/Al ratio of Y, Y-550-HN, Y-600-HN, Y-650-HN were increased to 3.1765, 6.6706, 7.3079, and 7.4635, respectively. Whereas it was confirmed that structural crystallization due to high heat treatment temperature affected performance degradation. Therefore, there is an optimal heat treatment temperature of Y-zeolite, optimum modification condition study could be a substitute for activated carbon as a condition for producing an adsorbent having high durability and stability.

• Korean Chemical Engineering Research
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• v.44 no.3
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• pp.307-313
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• 2006

In order to improve the efficiency of methane steam reforming process, a part of the system which produces hydrogen from heavy hydrocarbon resources such as coal, we combined metal catalyst with CaO sorbent and fabricated catalyst/sorbent. To increase the porosity and the compressive strength of sorbent, carbon black and ${\alpha}-alumina$ were mixed with CaO powder during preparation. The effects of sorbent composition on the physical properties were investigated by SEM, TGA, BET, XRD, abrasion strength measuring device and adsorption-desorption instrument. Sorbent with 5 wt％ $Al_2O_3$ and 10 wt％ carbon black showed the best physical features with $7.61kg_f$ strength and 47％ $CO_2$ adsorption capability. Various metal catalysts such as Ni, Co and Fe were supported on the sorbent developed and 10 wt％ Ni/sorbent was selected for methane steam reforming process based on the result of reaction experiment. The reaction system using the catalyst/sorbent showed better $H_2$ productivity compared to the detached system with catalyst and sorbent, indicating the effectiveness of the system developed in this study.