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고분자 전구체 용액으로부터 분무열분해법에 의해 합성되어진 구형 형상의 Y<sub>2</sub>SiO<sub>5</sub>:Ce 형광체
강희상,강윤찬,박희동,설용건,Kang, H.S.,Kang, Y.C.,Park, H.D.,Shul, Y.G. 한국재료학회 2003 한국재료학회지 Vol.13 No.3
Ce-doped $Y_2$SiO$_{5}$ phosphor particles of spherical morphology, fine size, high crystallinity and high photoluminescence (PL) intensity were prepared by spray pyrolysis. When nitrate precursor solution is adopted, hollow particles were formed by uneven drying rate between surface and inside of droplet. Citric acid and ethylene glycol were introduced as polymeric precursor to control the morphology of particles. When polymeric solution is adopted, polymeric chain is formed by the esterification reaction between carboxyl and hydroxy groups of citric acid and ethylene glycol, and considered as controlling the drying characteristics of droplet. $Y_2$$SiO_{5}$ :Ce phosphor particles prepared from polymeric precursor solution were spherical, filled, fine size and not agglomerate before and after post heat treatment. The optimum doping concentration of cerium was 0.5 mol% of overall solution concentration. The optimum amount of TBOS of high PL intensity and pure crystallinity of X2-type $Y_2$$SiO _{5}$ was 105% of stoichiometric amount. The PL intensity of $Y_2$X$/_{5}$ :Ce phosphor particles prepared using the polymeric precursor solution was 164% of that of the nitrate precursor solution due to homogeneous composition and good morphology.y.
H-ZSM-5와 Zn으로 개조된 H-ZSM-5 촉매를 이용한 n-butane의 탈수소화 반응에 관한 연구
양재춘,설용건,김길용 연세대학교 산업기술연구소 1997 논문집 Vol.29 No.1
The dehydrogenation of n-butane was studied on a series of H-ZSM-5 and Zn-ZSM-5 having various SiO₂/Al₂O₃ ratios(70. 100. 500). As SiO₂/Al₂O₃ratio is decreased, the conversion of n-butane and the selectivity to aromatics are increase, while that to olefins is decreased. In comparison with H-ZSM-5, Zn-ZSM-5 exhibited high selectivity to aromatics as well as enhanced total conversion of n-butane with decreasing olefins selectivity. The effects of Zn addition on n-butane dehydrogenation was explained by enhancement of n-butane conversion on acid sites by hydrogen reverse-spillover on Zn. Zn-ZSM-5, Zincaluminosilicate and Zincsilicate, that were synthesized with changing the distance between acid site and Zn, showed the differences in the reactivity, but much higher than H-ZSM-5 in the dehydrogenation of n-butane.
양재춘,설용건,신채호 연세대학교 산업기술연구소 1997 논문집 Vol.29 No.1
Titanium oxynitride was prepared with the nitridation of TiO₂ gel with NH₃ at the temperature range of 350-650℃. The degree of nitridation and the crystalline phase of prepared TiON were greatly affected by the types of precursor and the usage of chelating agent(ethylene diamine). The modification of titanium isopropoxide with ethylene diamine was effective to obtain the titanium oxynitride much lower temperature than that of TiO₂ without additive. The TiON/ZSM-5 could be prepared with the nitridation of ZSM-5 coated with titanium isopropoxide sol. The morphology and the crystalline phase of ZSM-5 was maintained after the nitridation with NH₃ at 700℃.
DCA(Dichloroacetic acid) Decomposition over Photoreduced Metal Supported TiO_2-SiO_2 Catalysts
Shul, Y.G.,Yang, J.C.,Kim, Y.C.,Yoo, H.J.,Lee, T.K. 전남대학교 촉매연구소 1997 촉매학술발표회 Vol.- No.14
The dichloroacetic acid (DCA) decomposition was studied over photoreduced metal supported TiO_2 and TiO_2-SiO_2 catalysts. The enhancement of photocatalytic activity was achieved by the photoreduction of Pt supported TiO_2 with UV light. The maximum photocatalytic activity was observed at 1.68 wt % of Pt loading. The synergistic effect was observed in the case of doping tungsten and platinum together. TiO_2-SiO_2 mixed oxide was synthesized by sol-gel process and then it was calcined at 400 ℃. When the TiO_2 content was higher than anatase phase found, apparently there was no crystalline peak below 30% of TiO_2 in SiO_2. The photon effiency of DCA decomposition over TiO_2-SiO_2 catalyst also increased when platinum was supported by photoreduction.
Jeon, Y.,Lee, C.,Rhee, J.,Lee, G.,Myung, J.h.,Park, M.,Park, J.I.,Einaga, H.,Shul, Y.G. Elsevier Ltd 2017 Fuel Vol.187 No.-
A novel synthesis of morphology-controlled perovskite networked with LaCr<SUB>0.8</SUB>Ru<SUB>0.2</SUB>O<SUB>3</SUB> nanoparticles was introduced using activated carbons as sacrificial templates. These catalysts were used for the hydrogen production by heavy-hydrocarbon autothermal reforming. To investigate the effect of the carbon templates, morphology-controlled perovskites using activated carbons and a non-templated catalyst were prepared to determine how carbon templates influence the chemical structure of the perovskite. The carbon templates produced a crystalline structure with the well incorporation of Ru under mild calcination conditions. The morphology of the hollow fibers provided a higher specific surface area than that of the porous grain catalyst with a similar average particle size (~80nm). It was found that the hollow fibers showed a unique pore structure with large macropores from 1 to 100μm, which might offer a higher surface area and enhanced mass transfer of the reactants. This provided a higher activation energy for H<SUB>2</SUB> production than the porous grain and non-templated catalysts during the autothermal reforming of heavy hydrocarbons. As a result, the fibrous feature and well-defined chemical structure were crucial factors when cracking the hydrocarbon chain. The hollow fiber catalyst showed high reforming efficiency for H<SUB>2</SUB> production (>65mol%) from heavy-hydrocarbon fuels during long-term experiments, featuring substantial durability with low carbon deposition and no structural changes.
Lee, Y.,Jang, J.,Lee, J.G.,Jeon, O.S.,Kim, H.S.,Hwang, H.J.,Shul, Y.G. Pergamon Press 2016 ELECTROCHIMICA ACTA Vol.220 No.-
Highly active and durable non-platinum catalysts for oxygen-reduction reaction (ORR) have been developed for energy conversion devices such as proton-exchange membrane fuel cells (PEMFCs). In this study, Pd-Fe-Mo catalyst is reported as a non-platinum catalyst for ORR. The atomic ratio and annealing temperatures are controlled on the catalysts to understand interplay between their physical and chemical properties and electrochemical activities. The Pd-Fe-Mo catalyst optimized with 7.5:1.5:1.0 of the atomic ratio and 500<SUP>o</SUP>C of the annealing temperature shows 32.18mAmg<SUP>-1</SUP><SUB>PGM</SUB> (PGM: platinum group metal) of the kinetic current density at 0.9V for ORR, which is comparable to that of commercial Pt/C catalyst. The current density is degraded to 6.20mAmg<SUP>-1</SUP><SUB>PGM</SUB> after 3000 cycling of cyclic voltammetry, but it is greatly enhanced value compared to other non-platinum catalysts. In actual application to PEMFCs, the 20% Pd-Fe-Mo catalyst supported on carbons exhibits a high performance of 506mAcm<SUP>-2</SUP> at 0.6V. The results suggest that the Pd-Fe-Mo catalyst can be a good candidate for non-platinum ORR catalysts.