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분무 열분해법으로 제조한 비다지 Co-Mo 촉매의 티오펜 탈황반응
조일현(Ihl Hyun Cho),강윤찬(Yun Chan Kang),박승빈(Seung Bin Park) 한국화학공학회 1997 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.35 No.6
The role of Mo and Co in unsupported Co-Mo catalyst of various Co/Mo ratio prepared by spray pyrolysis method was investigated. The structure and morphology of unsupported Co-Mo were studied by BET surface area, X-Ray diffraction pattern(XRD), scanning electron microscopy(SEM), and transmission electron microscopy(TEM). The catalytic activity was tested by the thiophene hydrodesulfurization(HDS) at 400℃ and atmospheric pressure. The crystal phase of unsupported Co-Mo was changed with Co/Co+Mo(=r) ratio, as revealed by XRD. The MoO₃ and CoMoO₄ were formed below r=0.2. After the sulfidation with H₂S/H₂, the bulk MoO₂ crystals, Co_9S_8 crystals, and MoS₂ nanocrystal were formed. The MoO₂ was formed by the reduction of MoO₃, and the Co_9S_8 was formed by the segregation of CoMoO₄. A typical synergistic effect and the highest catalytic activities were observed for the unsupported Co-Mo catalysts when r varies from 0.1 to 0.2 in the thiophene HDS reaction. These results indicated that both MoO₂ and Co_9S_8 act as a support for highly dispersed MoS₂. The further addition of Co(r>0.2) leaded to the formation of only CoMoO₄ which was transformed into the Co_9S_8 and MoS₂ after the sulfidation. The bulk Co sulfide. like MoO₂ served as a carrier for good dispersion of MoS₂. The promotional effect was also observed in HDS reaction.
Co - Mo / Al2O3 졸 - 겔 촉매의 수첨탈황 반응성
김유정,조일현,박승빈,임선기 ( Yu Jeong Kim,Ihl Hyun Cho,Seung Bin Park,Son Ki Ihm ) 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.6
Co-Mo/Al₂O₃sol-gel catalysts have been investigated by X-ray diffraction(XRD) FTIR BET and TEM, and thiophene hydrodesulfurization(HDS) and their activities were compared with that of impregnated catalyst. A series of sol-gel catalysts were prepared by mixing Co-, Mo-acetylacetonate(Co-, Mo-acac) with alumina sol, or by impregnating dried gel or calcined gel with these precursors. The alumina sol was obtained from hydrolysis of Al(OR)₃ with excess water and peptization of the resultant hydrate with HNO₃. The reference catalyst was prepared by impregnating γ-Al₂O₃ with aqueous solution of cobalt nitrate and ammonium molybdate. For the sol-gel catalyst formed from mixing all Co- Mo-acac with alumina sol, the HDS activity was lower than that of reference catalyst. However, HDS activity was significantly increased to the activity of the reference catalyst, when the half of Co-, Mo-acac were mixed with alumina sol and the rest of them were impregnated into calcined gel. For the catalyst first formed from alumina sol mixed with only Co-acac, followed by impregnating a Mo-acac solution into the calcined gel, HDS activity was lower than that of catalyst prepared by reversing the order of adding Co-acac and Mo-acac. This reduction of activity results from the absence of synergic effect due to the migration of cobalt into the alumina matrix during sol-gel process. The impregnated cobalt are, however, deposited on the surface of the preoccupied MoO₃ fine crystallite, so that HDS activity is increased due to the synergic effect. The sol-gel catalysts have a micropore of about 2 ㎚ in radius which affects the access of thiophene reactants to active sites, thereby lowering the HDS activity of sol-gel catalysts than that of conventional cobalt-molybdenum on gamma alumina catalyst.
다공성 알루미나 관에 지지된 Pd / Al2O3 복합막의 졸 - 겔법에 의한 제조와 분리특성
이승진,조일현,김기영,양승만,박승빈 ( Seung Jin Lee,Ihl Hyun Cho,Ki Young Kim,Seung Man Yang,Seung Bin Park ) 한국화학공학회 1995 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.33 No.1
Composite alumina membrane was prepared for the hydrogen separation from H₂-N₂ mixture gas. The membrane was formed in a porous alumina support by coating with boehmite sol mixture by Yoldas method[9] with 5 wt% concentration of Pd in dry base. Sonication of the sol mixture increased the Pd dispersion compared to that of conventional impregnation method. In order to facilitate penetration of the sol, the inner side of the porous alumina support was maintained at the vacuum condition of 20 torr during the coating procedure. Tortuosity of the resulting membrane was increased from 10 to 20. The selectivity also increased up to 10 because of the activated diffusion by the Pd particles dispersed in the alumina membrane layer. Sealing between membrane housing and supported membrane was designed to endure high temperature operation and provided a way to develop alumina membrane module.