• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.90-95
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• 2000

The ferrites, CuFe2O4 and SrFe12O129, were applied to decompose H2O for H2 generation. The ferrites prepared by the coprecipitation were reduced by CH4 gas to make the oxygen deficient ferrite. H2O was decomposed to form H2 by the oxygen deficient iron oxide, and the decomposition reactions were accelerated by the addition of divalent metals such as Cu and Sr in the ferrites. The spinel type CuFe2O4 containing a relatively large amount of divalent metals was more effective to H2 generation than magnetoplumbite type SrFe12O19 in H2O decomposition.

• Journal of the Korean Ceramic Society
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• v.37 no.2
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• pp.164-167
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• 2000

Flue gases in the iron foundry consist of 15~20% CO2 as an air pollution gas whose emission should be mitigated in order to protect the environment. In the present study, ultrafine powders of NixZn1-xFe2O4 as a potential catalyst for the CO2 decomposition were prepared by the coprecipitation methods. Oxygen deficient ferrites (MeFe2O4-$\delta$) can decompose CO2 as C and O2 at a low temperature of about 30$0^{\circ}C$. The XRD result of synthesized ferrites showed the spinel structure of ferrites and ICP-AES and EDS quantitative analyses showed the composition similar with initial molar ratios of the mixed solution prior to reaction. The BET surface area of the (Ni, Zn)-ferrites was about 77~89.5$m^2$/g and their particle size was observed about 10~20 nm. The CO2 decomposition efficiency of the oxygen deficient (Nix, Zn1-x)-ferrites was the highest at x=0.3, and the ternary (Ni, Zn)-ferrites was better than that of binary Ni-ferrites.

• Korean Journal of Materials Research
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• v.10 no.3
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• pp.223-226
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• 2000

The oxygen deficient ferrites $(Ni_x,\; Zn_{1-x})Fe_2O_{4-{\delta}}$ can decompose $CO_2$ as C and $O_2$ at a low temperature of about $300^{\circ}C$. Ultra powders of $(Ni_x,\; Zn_{1-x})Fe_2O_4$ for the $CO_2$ decomposition were prepared by the hydrothermal methods. The XRD result of synthesized ferries showed the spinel structure of ferrites and ICP-AES and EDS quantitative analyses showed the composition similar with the starting molar ratios of the mixed solution prior to reaction. The BET surface area of the synthesized(Ni, Zn)-ferrites was above $110\textrm{m}^2/g$ and its particle size was very as small as about 5~10 nm. The $CO_2$ decomposition efficiency of the oxygen deficient ferrites($(Ni_x,\;Zn_{1-x})Fe_2O_{4-{\delta}}$) was almost independent with composition and the $CO_2$ decomposition efficiency of ternary (Ni, Zn)-ferrites was better than of binary Ni-ferrites.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2009.10a
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• pp.218-219
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• 2009

• Journal of the Korean Ceramic Society
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• v.37 no.10
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• pp.962-967
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• 2000

산소 결핍 페라이트 (oxygen deficient ferrites, ODF) MF $e_2$ $O_{4-}$$\delta$/는 약 30$0^{\circ}C$의 낮은 온도에서 온실가스중 하나인 $CO_2$를 C와 $O_2$로 분해시킨다. 본 연구에서는 $CO_2$분해 촉매로서 3원계 초미세 페라이트 N $i_{x}$Z $n_{1-x}$F $e_2$ $O_4$와 N $i_{x}$ $Co_{1-x}$F $e_2$ $O_4$를 수열합성법과 공침법 등의 습식 합성법으로 각각 합성하여 이들 분말의 특성과 $CO_2$분해 특성을 고찰하였다. 페라이트의 XRD 결과, 결정구조는 모두 전형적인 스피넬 구조로 동일하게 나타났다. BET 비표면적은 수열합성법으로 제조한 3원계 페라이트의 경우 110$m^2$/g 이상으로 공침법으로 제조한 페라이트보다 비교적 큰 값을 나타냈고 분말 입자크기 또한 약 10nm의 매우 미세한 분말을 얻을 수 있었다. 3원계 산소 결핍 페라이트의 $CO_2$분해 효율은 공침법으로 합성한 것보다 수열합성법으로 합성한 것이 더 우수하게 나타났으며, N $i_{x}$ $Co_{1-x}$F $e_2$ $O_{4-}$$\delta$/보다 N $i_{x}$Z $n_{1-x}$F $e_2$ $O_{4-}$$\delta$/가 우수한 것으로 나타났다.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.185-189
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• 2011

In this work, nano-sized M-ferrites (M=Co, Ni, Cu, Zn) for the decomposition of carbon dioxide were synthesized by the chemical co-precipitation. From the thermogravimetric analysis, it was clear that the maximum weight loss of each sample took place below $350^{\circ}C$. High temperature calcination resulted in more systematic crystallines, smaller specific surface area and larger particle size. An analysis by FTIR in the range of $375{\sim}406cm^{-1}$ revealed the presence of chelates at the octahedral site, which implies the formation of spinel structure in the ferrites. The current work showed that a $500^{\circ}C$ is the optimum heat treatment temperature of metal ferrites for $CO_2$ decomposition reaction.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.657-662
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• 2002

The reduced ferrites, reduced NiF $e_2$ $O_4$ and CuF $e_2$ $O_4$, by C $H_4$ were applied to $CO_2$ decomposition to avoid the greenhouse effects. At the reduction reaction above $700^{\circ}C$, $H_2$ and CO were generated by partial oxidation of C $H_4$ After the reduction reaction up to 80$0^{\circ}C$, the spinel structure ferrites changed to mixture of the oxygen deficient iron oxide (Fe $O_{(1-{\delta})}$(0$\leq$$\delta$$\leq$1)) and the metallic Ni or Cu. The rate and quantity of $CO_2$ decomposition with reduced CuF $e_2$ $O_4$ were larger than those with reduced NiFe $O_4$. The $CO_2$ gas was decomposed by oxidation of the oxygen deficient iron oxide. The metallic Cu and Ni were not oxidized and remained in a metallic state up to 80$0^{\circ}C$. The $CO_2$ decomposition reaction with the reduced ferrite by C $H_4$ gas is excellent process preparing useful gas such as $H_2$and CO and decomposing $CO_2$ gas.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.801-806
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• 2002

The decomposition and/or conversion of carbon dioxide to carbon have been studied using oxygen-deficient ferrites for the reduction of $CO_2$ emission to the atmosphere. In this work, the homogeneous precipitation method using urea decomposition was employed to induce in situ precipitation of Ni ferrite($Ni_{0.4}Fe_{2.6}O_4$) on the porous ceramic fiber support (50 mm diameter${\times}$10 mm thickness). Effects of ferrite loading conditions on the CO2 decomposition efficiency were discussed in this paper. Removal of residual chloride ions and urea by solvent exchange from the porous media after ferrite deposition apparently helps to form spinel ferrite, but does not increase the efficiency of $CO_2$ decomposition. Porous ceramic fiber composites containing 20 wt% (1g) ferrite samples showed 100% efficiency for $CO_2$decomposition during the first three minutes, but the efficiency decreased rapidly after the elapsed time of ten minutes. The characteristic reduction time for the $CO_2$ decomposition efficiency was estimated as about 3∼7 min.