• 제목/요약/키워드: liquid-solid reactions

검색결과 37건 처리시간 0.025초

Reactions of Aryl Halides with Phenoxides and Alkoxides by Phase Transfer Catalysis

  • 조봉래;박성대
    • Bulletin of the Korean Chemical Society
    • /
    • 제5권3호
    • /
    • pp.126-129
    • /
    • 1984
  • The reaction of aryl halides with phenoxides and alkoxides were investigated under phase transfer catalytic conditions. 2,4-Dinitro- and 4-nitrohalobenzenes reacted readily with phenoxides in NaOH(aq)-benzene in the presence of Bu4N+Br, affording the products quantitatively. Although the aryl halides did not react with alkoxides under the same condition, the reactions were completed within 2 hours at room temperature when conducted under solid-liquid phase transfenr catalytic condition. The reactivity of aryl halides was in the order, Ar = 2,4-dinitrophenyl > 4-nitrophenyl, and X = F > Cl, consistent with the SNAr mechanism. The reactivity of oxyanions increased with the change of reaction condition from liquid-liquid to solid-liquid phase transfer catalysis. The results were explained with the concentration and the degree of hydration of the anion in benzene.

芳香族할라이드의 Hot Atom Chemistry 스캐벤져, 溫度 및 酸素의 效果 (Hot Atom Chemistry of Aromatic Halides : Scavenger, Temperature and Oxygen Effect)

  • 최재호;박용찬;손미자
    • 대한화학회지
    • /
    • 제9권2호
    • /
    • pp.78-80
    • /
    • 1965
  • The organic yields(i.e., fraction of nuclear events resulting in organic compound formation) of the radioactive neutron capture reactions of the halogens in purified aromatic halides have been determined in the liquid and solid state, in the presence of scavenger, elemental halogen for thermal atoms, and in the presence of oxygen. Among the important results are; (1) organic yields of the halides are due in part to hot processes and in part to thermal processes; (2) temperature (from liquid state to solid state); (3) the organic yield of chlorobenzene is the same in the solid phase as in the liquid phase whereas the yields of the bromo-and iodobenzene are higher in the solid.

  • PDF

Solid-liquid phase equilibria on the GdBa2Cu3O7-δ stability phase diagram in low oxygen pressures (1 - 100 mTorr)

  • Lee, J.W.;Lee, J.H.;Moon, S.H.;Yoo, S.I.
    • 한국초전도ㆍ저온공학회논문지
    • /
    • 제14권4호
    • /
    • pp.28-31
    • /
    • 2012
  • We report the solid-liquid phase equilibria on the $GdBa_2Cu_3O_{7-{\delta}}$ (GdBCO) stability phase diagram in low oxygen pressures ($PO_2$) ranging from 1 to 100 mTorr. On the basis of the GdBCO stability phase diagram experimentally determined in low oxygen pressures, the isothermal sections of three different phase fields on log $PO_2$ vs. 1/T diagram were schematically constructed within the $Gd_2O_3-Ba_2CuO_y-Cu_2O$ ternary system, and the solid-liquid phase equilibria in each phase field were described. The invariant points on the phase boundaries include the following three reactions; a pseudobinary peritectic reaction of $GdBCO{\leftrightarrow}Gd_2O_3$ + liquid ($L_1$), a ternary peritectic reaction of $GdBCO{\leftrightarrow}Gd_2O_3+GdBa_6Cu_3O_y$ + liquid ($L_2$), and a monotectic reaction of $L_1{\leftrightarrow}GdBa_6Cu_3O_y+L_2$. A conspicuous feature of the solid-liquid phase equilibria in low $PO_2$ regime (1 - 100 mTorr) is that the GdBCO phase is decomposed into $Gd_2O_3+L_1$ or $Gd_2O_3+GdBa_6Cu_3O_y+L_2$ rather than $Gd_2BaCuO_5+L$ well-known in high $PO_2$ like air.

로켓 추진기관용 C/SiC 내열부품 개발 (Development of C/SiC Composite Parts for Rocket Propulsion)

  • 김연철;서상규
    • 한국추진공학회지
    • /
    • 제23권2호
    • /
    • pp.68-77
    • /
    • 2019
  • 고체 및 액체 로켓 추진 기관 내열부품으로 사용하기 위하여 C/SiC 복합 재료를 LSI(Liquid Silicon Infiltration) 공법으로 개발하였다. 조성비에 따른 내열 특성은 아크 플라즈마, 초음속 토치 시험으로 평가하였으며 $H_2O$$CO_2$ 산화에 의한 유효 삭마식을 제시하였다. 연소시험을 통하여 고체 및 액체 추진기관용 노즐목 삽입재, 확대부 내열재 및 연소실 내열부품 등 다양한 형상으로 제작이 가능함을 확인하였으며 높은 내삭마 성능과 열구조 성능이 입증되었다.

Residual salt separation technique using centrifugal force for pyroprocessing

  • Kim, Sung-Wook;Lee, Jong Kwang;Ryu, Dongseok;Jeon, Min Ku;Hong, Sun-Seok;Heo, Dong Hyun;Choi, Eun-Young
    • Nuclear Engineering and Technology
    • /
    • 제50권7호
    • /
    • pp.1184-1189
    • /
    • 2018
  • Pyroprocessing uses various molten salts during electrochemical unit processes. Reaction products after the electrochemical processes must contain a significant amount of residual salts to be separated. Vacuum distillation is a common method to separate the residual salts; however, its high operation temperature may cause side reactions. In this study, a simple rotation technique using centrifugal force was suggested to separate the residual salts from the reaction products at relatively low temperature compared to the distillation technique. When a reaction product container with porous wall rotates inside a vessel heated above the melting point of the residual salt, the residual salt in the liquid phase is separated through centrifugal force. It was shown that the $LiNO_3-Al_2O_3$ mixture can be separated by this technique to leave solid $Al_2O_3$ inside the container, with a separation efficiency of 99.4%.

리튬금속과 고체전해질의 계면 반응 (Interfacial Reaction between Li Metal and Solid Electrolyte in All-Solid-State Batteries)

  • 김재헌
    • Corrosion Science and Technology
    • /
    • 제22권4호
    • /
    • pp.287-296
    • /
    • 2023
  • Li-ion batteries have been gaining increasing importance, driven by the growing utilization of renewable energy and the expansion of electric vehicles. To meet market demands, it is essential to ensure high energy density and battery safety. All-solid-state batteries (ASSBs) have attracted significant attention as a potential solution. Among the advantages, they operate with an ion-conductive solid electrolyte instead of a liquid electrolyte therefore significantly reducing the risk of fire. In addition, by using high-capacity alternative electrode materials, ASSBs offer a promising opportunity to enhance energy density, making them highly desirable in the automotive and secondary battery industries. In ASSBs, Li metal can be used as the anode, providing a high theoretical capacity (3860 mAh/g). However, challenges related to the high interfacial resistance between Li metal and solid electrolytes and those concerning material degradation during charge-discharge cycles need to be addressed for the successful commercialization of ASSBs. This review introduces and discusses the interfacial reactions between Li metal and solid electrolytes, along with research cases aiming to improve these interactions. Additionally, future development directions in this field are explored.

차세대 리튬이차전지를 위한 산화물 고체전해질의 연구동향 (Research progress of oxide solid electrolytes for next-generation Li-ion batteries)

  • 강병우;박희택;우승준;강민석;김아빈
    • 세라미스트
    • /
    • 제21권4호
    • /
    • pp.349-365
    • /
    • 2018
  • Since the electrification of vehicles has been extended, solid-state batteries have been attracting a lot of interest because of their superior safety. Especially, polymer, sulfide, and oxide based materials are being studied as solid electrolytes, and each type of materials has advantaged and disadvantages over others. Oxide electrolytes has higher chemical and electrochemical stability compared to the other types of electrolytes. However, ionic conductivity isn't high enough as much as that of organic liquid electrolytes. Also, there are many difficulties of fabricating solid-state batteries with oxide based electrolytes because they require a sintering process at very high temperature (above ${\sim}800^{\circ}C$). Herein, we review recent studies of solid-state batteries with oxide based electrolytes about the ionic conductivity, interfacial reactions with Li metal, and preparation of solid-state cell.

고체초강산 촉매와 그 응용 (Solid Superacid Catalyst and Its Application)

  • 손종락
    • 공업화학
    • /
    • 제3권1호
    • /
    • pp.7-17
    • /
    • 1992
  • 100% $H_2SO_4$($H_0=-11.93$)보다 더 강한 산을 초강산이라고 한다. 그러나 고체초강산 촉매는 액체초강산촉매에 비하여 촉매와 반응생성물의 분리의 용이성, 촉매의 반복사용가능, 촉매의 재생가능 등과 같은 많은 이점을 가지고 있다. 이 총설에서는 고체초강산 촉매의 종류, 제법, 그리고 화학반응에서의 응용에 대하여 소개한다.

  • PDF

Degradation Mechanisms of a Li-S Cell using Commercial Activated Carbon

  • Norihiro Togasaki;Aiko Nakao;Akari Nakai;Fujio Maeda;Seiichi Kobayashi;Tetsuya Osaka
    • Journal of Electrochemical Science and Technology
    • /
    • 제14권4호
    • /
    • pp.361-368
    • /
    • 2023
  • In lithium-sulfur (Li-S) batteries, encapsulation of sulfur in activated carbon (AC) materials is a promising strategy for preventing the dissolution of lithium polysulfide into electrolytes and enhancing cycle life, because instead of solid-liquid-solid reactions, quasi-solid-state (QSS) reactions occur in the AC micropores. While a high weight fraction of sulfur in S/AC composites is essential for achieving a high energy density of Li-S cells, the deterioration mechanisms under such conditions are still unclear. In this study, we report the deterioration mechanisms during charge-discharge cycling when the discharge products overflow from the AC. Analysis using scanning electron microscopy and energy-dispersive X-ray spectrometry confirms that the sulfur in the S/AC composites migrates outside the AC as cycling progresses, and it is barely present in the AC after 20 cycles, which corresponds to the capacity decay of the cell. Impedance analysis clearly shows that the electrical resistance of the S/AC composite and the charge-transfer resistance of QSS reactions significantly increase as a result of sulfur migration. On the other hand, the charge-discharge cycling performance under limited-capacity conditions, where the discharge products are encapsulated inside the AC, is extremely stable. These results reveal the degradation mechanism of a Li-S cell with micro-porous carbon and provide crucial insights into the design of a S/AC composite cathode and its operating conditions needed to achieve stable cycling performance.