• Journal of the Korean Chemical Society
• /
• v.32 no.5
• /
• pp.501-506
• /
• 1988

The effects of alkali promoters on the activity and selectivity of Co/NaY catalyst have been investigated. The catalysts were prepared by impregnating NaY with aqueous solutions of alkali compounds and a benzene solution of $Co_2(CO)_8$. Hydrocarbon synthesis was studied in a flow reactor under the reaction conditions : temperature = 200∼250$^{\circ}C$, space velocity = 120∼$160hr^{-1}$, pressure = 1 atm, $H_2$/CO = 1. As the basicity of alkali promoter increases, the olefin selectivity, probability of chain growth, and CO$_2$ formation increase and methane formation decreases. The activity of CO hydrogenation increases with the pH of alkali solutions.

• Journal of the Korean Chemical Society
• /
• v.39 no.4
• /
• pp.275-280
• /
• 1995

The electron transfer reactions between cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2-(Y=EDTA, PDTA, CyDTA) have been investigated in the presence of hydrogen ion. From the kinetic data, it has been found that electron transfer reactions between cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- proceed via inner-sphere pathway by catalysis of hydogen ion. The stereoselectivity in the electron transfer reactions between optically active △-cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- produced 6.0, 2.9, 3.0% e.e.(e.e.=enantiomeric excess) of △-[Co(EDTA)]-, △-[Co(PDTA)]- and △-[Co(CyDTA)]-, respectively. Based upon this observation, it seems that △-cis-[Co(en)2(NO2)2]+ is associated with rac-[Co(Y)]2- at first, and followed by the electron transfer reaction. Therefore, it was suggested that stereoselective electron transfer reaction between △-cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- proceed through both inner-sphere by the proton catalysis and outer-sphere with ionic association.

• Resources Recycling
• /
• v.11 no.3
• /
• pp.10-16
• /
• 2002

In the leaching of $LiCoO_2$with a strong acid such as sulfuric and nitric acid, an additional step was needed to recover cobalt and lithium separately from spent lithium ion batteries (LIBs). The leaching of $LiCoO_2$in an oxalic acid solution was investigated to recover cobalt selectively using a low solubility of cobalt oxalate at low pH. Leaching efficiency of 95% of lithium and less than 1% of cobalt were obtained when pure $LiCoO_2$powder was leached in 3M oxalic acid at $80^{\circ}C$ and 50 g/L pulpdensity. Under the above leaching conditions, complete dissolution of lithium was accomplished with mere 0.25% of cobalt in the solution when the cathodic active material collected from spent LIBs was employed. The lithium in the leaching solution can be recovered as a form of carbonate or hydroxide depending on the addition of $Na_2$$CO_3$or LiOH.

• Membrane Journal
• /
• v.17 no.3
• /
• pp.269-275
• /
• 2007

Sodium type faujasite(FAU) zeolite membranes with a thickness of 5${\mu}m$ and a Si/Al molar ratio of 1.5 were prepared by the secondary growth process. The $CO_2/N_2$ separation in the vacuum mode was investigated at $30^{\circ}C$ for an equimolar $CO_2-N_2$ mixed gas before and after embedding 13X zeolite beads in the permeate side. The embedded 13X zeolite beads improved both $CO_2$ permeance and $CO_2/N_2$ separation factor, simultaneously. The phenomenon was explained by an increment in the $CO_2$ desorption rate at the FAU zeolite/$\alpha-Al_2O_3$ phase boundary due to an enhanced $CO_2$ escaping through the pore channels of the $\alpha-Al_2O_3$ support layer. In the present paper, it will be emphasized that a hybridization of a membrane with an adsorbent can provide a key to break through the trade-off between permeance and separation factor, generally shown in a membrane separation.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.5 no.1
• /
• pp.19-29
• /
• 2002

In this paper, the selection of transport route for import-export container cargo based on the sacrifice model and CO₂ emission was investigated. At first, the transportation of import-export container cargo, the transport share of each transport route, the CO₂ gas emission, the sacrifice model and the time value of import-export container cargo were investigated. And next, the selection of transport route based on the sacrifice model was investigated for the transport of import-export container cargo from Seoul to Pusan Port. Finally, the transport route was also selected by using the sacrifice model including the effect of CO₂ emission. The research results show that the transport route selection results of import-export container cargo based on the sacrifice model represents the present status of the transportation of import-export container cargo very well. And also the research results show that the reduction of transport time was very effective to increase the share of coastal transportation.

• Membrane Journal
• /
• v.31 no.3
• /
• pp.200-211
• /
• 2021

In this study, mixed matrix membranes were prepared by mixing the synthesized zeolitic imidazolate framework-7 (ZIF-7) with poly(ether-b-amide) 2533 (PEBAX2533). A single gas (N₂, CO₂) was permeated through the membrane to investigate the properties of the gas. Through FT-IR, XRD, and FE-SEM, the peaks and shapes of ZIF-7 were confirmed, and it was determined that the synthesis was successful. Through TGA, it was confirmed that ZIF-7 has excellent thermal stability and that when incorporated into the membrane, the thermal stability is improved compared to pure PEBAX2533. It was found that ZIF-7 synthesized through BET had excellent CO₂ adsorption capacity and CO₂/N₂ adsorption selectivity showed a high value of about 49.64. For the gas permeation, as the ZIF-7 content in the mixed membrane increases, the N₂ permeability decreases and the CO₂ permeability slightly decreases, while the CO₂/N₂ selectivity steadily increases. In particular, when 20 wt% of ZIF-7 was added, the CO₂ permeability did not decrease significantly and the CO₂/N₂ selectivity increased considerably, resulting in the performance approaching to the Robeson upper-bound.

• Membrane Journal
• /
• v.31 no.6
• /
• pp.404-416
• /
• 2021

In this study, a mixed matrix membrane was prepared by varying the contents of GO and PEI-GO synthesized in PEBAX2533, and the permeation characteristics of N₂ and CO₂ were studied. The N₂ and CO₂ permeability of the PEBAX/GO mixed membrane decreased as the GO content increased, and showed the highest CO₂/N₂ selectivity of 58.9 at GO 0.3 wt%. For the PEBAX/PEI-GO mixed membrane, the N₂ permeability decreased as the PEI-GO content increased, and the CO₂ permeability showed a different trend according to the PEI-GO content. Overall, the CO₂/N₂ selectivity was higher than that of the PEBAX/GO mixed membrane. In particular, PEI-GO 0.3 wt% showed the highest CO₂/N₂ selectivity of 73.5 among the mixed membranes, and a positive result was obtained as it was located above the Robeson upper bound. This is believed to be due to the molecular sieving channel effect resulting from the original GO structure, the functional groups present in the structure of GO having affinity for CO₂, and the effect of amine bound to PEI by modifying GO into PEI.

• Membrane Journal
• /
• v.24 no.2
• /
• pp.100-106
• /
• 2014

In this work, soluble polyimides were synthesized and characterized from 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA) and two diamines such as 4,4'-diaminodiphenylether (ODA), 1,4-phenylenediamine (p-PDA). Their thermal properties were analyzed with differential scanning calorimeter (DSC). The gas permeability coefficients (P) and ideal selectivity for $CH_4$ and $CO_2$ of the prepared polyimide membranes were measured with a time-lag apparatus. DOCDA-ODA, DOCDA-p-PDA showed good permeability and selectivity; the permeabilities of $CO_2$ was 6.10, 0.74 barrers and the selectivity of $CO_2/CH_4$ were 67.03, 46.25, respectively. Therefore, DOCDA-ODA showed good possibility as gas separation membrane.

• Applied Chemistry for Engineering
• /
• v.26 no.4
• /
• pp.413-420
• /
• 2015

PTMSP-ZIF composite membranes were prepared by the addition of zeolitic imidazolate framework (ZIF-8) into poly (1-trimethylsilyl-1-propyne) (PTMSP) having high gas permeability to improve trade-off relationship of the polymer membrane. PTMSP-ZIF composite membranes were prepared with different amounts of ZIF-8; 0, 5, 10, 20, 30 and 40 wt%. Gas permeation properties for $H_2$, $N_2$, $CO_2$, and $CH_4$ were investigated by increasing the amount of ZIF-8 in the PTMSP. The gas permeability of PTMSP-ZIF composite membranes within 5~30 wt% of ZIF-8 contents increased as ZIF-8 contents went up and decreased thereafter. The gas permeability for $CO_2$ showed the maximum value of 76080 barrer at 30 wt% of ZIF-8 content and PTMSP-ZIF composite membrane containing 20 wt% of ZIF-8 content had the highest selectivity ($CO_2/N_2$) with the value of 8.2. The selectivity ($H_2/N_2$) and selectivity ($CO_2/CH_4$) were almost the same as PTMSP in the range 10~40 wt% of the ZIF-8. Overall, PTMSP-ZIF composite membranes resulted in maintained selectivity and increased permeability compared to those of PTMSP membranes.

• Membrane Journal
• /
• v.27 no.3
• /
• pp.226-231
• /
• 2017

1-Butyl-3-methylimidazolium tetrafluoroborate ($BMIM^+BF_4{^-}$) and $Al_2O_3$ as metal oxide for preparation of composite membrane were utilized for the $CO_2$ separation. When 13 nm $Al_2O_3$ nanoparticles were incorporated into ionic liquid $BMIM^+BF_4{^-}$, the separation performance for composite membrane showed the selectivity ($CO_2/N_2$) of 30.5 and $CO_2$ permeance of 45.7 GPU. The enhanced separation performance was attributable to the increased $CO_2$ solubility by both oxide layer of $Al_2O_3$ and abundant free ions of ionic liquid. In particular, $Al_2O_3$ nanoparticles acted as obstacles to nitrogen gas, resulting in the decrease of permeability of nitrogen gas. As a result, the carbon dioxide separation performance could be enhanced.