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Woo, Seong Ihl,Kim, Il 한국화학공학회 1990 NICE Vol.8 No.3
The kinetics for decawite of etW enu pulymerizution catalyzed with fiCl, IcCI. Sio. has been investiated in the rancc of temperatures tetaeen 40 and 90C and in the range of ethylene pressures bwen 4 and 13=I atm. hhe decay of IxIwerizalion rate eras fitted well ht the ype of first order dec. The deay rate constant caused by nunennrr could Ire expressed by k.i-C. M. Some plnusibl specnlaticms htwc been propnsed on the deactivtic? merlt mism caused by numomer. THE activation enery for the deactivation reaction is 9.3 kcal mole.
Woo, Seong Ihl,Park, Yong Ki,Hong, Suk Bong,Uh, Young Sun,Kim, Chang Gyoun 한국화학공학회 1992 NICE Vol.10 No.3
Vanado-, fern, and gallosilicate catalysts were prepared from the mixtures containing colloidal silica, corresponding metal source, tetrapropylammonium bromide and VHF by hydrothermal crystallization at 175 for 7 days. The pH value of the reaction mixture was low(pH$lt;8) compared to the conventional methods. The metal compounds have higher solubilites in these conditions than conventional conditions(pH$gt;10). The size distribution and the size of final products were found to be more homogeneous and larger than those of metallosilicates prepared in strong alkaline media. The characterization of metallosilicates with IR, X-ray diffraction, SEM, EPR, and ^(29)Si MAS NMR, indicated that corresponding metal atoms were successfully incorporated into the tetrahedral lattice sites of the ZSM-5 structure.
Woo, Seong Ihl,Kim, Seo Il,Kim, Choong Hyon 한국화학공학회 1995 Korean Journal of Chemical Engineering Vol.12 No.5
CoMo/Al₂O₃ catalysts were prepared by impregnating Cobalt nitrate solution into oxidic or sulfided Mo/Al₂O₃. The properties of CoMo/Al₂O₃ catalysts were characterized by XRD, TPS, oxygen chemisorption and ESR. Catalytic activity of CoMo/Al₂O₃catalyst was evaluated by thiophene HDS as a probe reaction. When CoMo/Al₂O₃ catalyst was prepared by impregnating Cobalt nitrate solution into sulfided Mo/Al₂O₃, the interaction between Mo and alumina became weaker and the formation of synergic phase was facilitated. These structural changes may explain higher HDS activity of CoMo/Al₂O₃ catalyst prepared by impregnating Cobalt nitrate solution into sulfided Mo/Al₂O₃.
Thermal Stability of [ B ] ZSM -5 Molecular Sieve
Woo, Seong Ihl,Hong, Suk Bong,Uh, Young Sun,Lee, Jae Kyu 한국화학공학회 1991 NICE Vol.9 No.2
The thermal stability of [B]ZSM-5 (boronsilicalite) has been examined by IR, XRD, ^(11)B MAS NMR and XPS techniques. [B]ZSM-5 and amorphous borosilicate were converted to a-cristobalite at ftigh temperatures (=750℃). However, Na-free amorphous borosilicate was not converted to a-cristobalite at 150℃. Therefcre, the presence of Naionsiat [B]ZSM-5 would determine whether this transition occurred or not. When the phase transition to a-crstoba(ite occurred, most of B atoms tetrahedrally coordinated were released from the ZSM-5 structure and migrated to the exterior surface as a boron compound having trigonal BO₃, units and oxidation states of 3.
Woo, Seong Ihl,Han, Jong Dae 한국화학공학회 1993 NICE Vol.11 No.6
The coordination changes of Co^(2+) in CoNaY/NaOHs, prepared by cobalt ion-exchange and treatment with NaOH, during dehydration at various temperatures have been investigated by UV/VIS diffuse reflectance spectroscopy. After dehydration of CoNaY/NaOHs at 473 K, the DRS bands show the formation of mixed cobalt oxide species interacted with lattice oxygen. This mixed cobalt oxide species interacted with lattice oxygen decompose during further dehydration at 673 K. The strong intensities of the bands at 650, 575 and 530 nor after dehydration of CoNaY/NaOHs at 873 K indicate that a considerable amount of the cobalt ions remains in the sodalite cage with tetrahedral coordination even after dehydration at 873 K.
AROMATIZATION OF PENTANE CATALYZED OVER VARIOUS METALLOSILICATES
Woo, Seong Ihl,Park, Yong Ki,Kim, Do Heui 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.4
Various metallosilicates were synthesized using a hydrothermal method and characterized by SEM, XRD, ^(29)Si MAS NMR, chemical analysis and surface area measurements. These results showed that they had a MFI structure. The pentane aromatization reaction was carried out over these metallosilicates in a continuous flow reactor at 550℃, He/pentane=3, WHSV=1.5 h^(-1) and 1 atm. Among the various metallosilicates, [Ga]ZSM-5(20) (52.3 %) and [Zn]ZSM-5(40) (37.6 %) showed higher aromatic selectivities for pentane aromatization. When [Al] ZSM-5(40) was ion-exchanged with gallium nitrate and zinc chloride, the selectivities for aromatics increased from 23.0 % to 35.5 % and to 32.7 %, respectively. The Si/metal mole ratios of [Ga]ZSM-5 and [Al]ZSM-5 were changed from 20 to 250 and NH₃ temperature programmed desorption (TPD) was carried out. As the Si/metal ratio was changed from 250 to 20, the selectivities for aromatics were increased from 5.3 % to 52.3 % over [Ga]ZSM-5 and from 10.1 % to 25.7 % over [Al]ZSM-5. NH₃TPD of [Ga]ZSM-5 indicated that the sites of medium acidity play an important role in the formation of aromatics. When H₂ and CO were added to the reactant of pentane, the production of methane and ethane increased and that of aromatics decreased.
Woo, Seong Ihl,Han, Taek Kyu,Ko, Young Soo 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.5
Silica supported MgCl₂/THF/TiCl₄catalyst (SiO₂/MgCl₂/THF/TiCl₄) was prepared, and then decomposed thermally. The amount of produced gas [tetrahydrofuran (THF) and 1,4-dichlorobutane (DCB)] was measured with gas chromatography (GC) and mass spectrometer. SiO₂/MgCl₂/THF/TiCl₄catalyst started to decompose around 85℃, and further decomposed at 113, 150 and 213℃. THF was mainly produced, but very small amount of DCB evolved during temperature programmed decomposition (TPD), while unsupported MgCl₂/THF/TiCl₄produced DCB significantly. Polymerization rate of ethylene with SiO₂/MgCl₂/THF/TiCl₄decreased when it was preheated at 85 and 110℃ for 5 and 60 min, respectively, while that of unsupported MgCl₂/THF/TiCl₄increased after same pretreatment condition. It can be suggested that Mg/Ti bimetallic complex anchored on the surface of silica through OH group of it has weak interaction between Mg and Ti species.