Mg - ZSM -22 촉매상에서 1- 부텐의 골격이성화 반응 특성에 관한 연구

백성현,최영헌,이화영 ( Sung Hyeon Baeck,Young Heon Choe,Wha Young Lee ) 한국화학공학회 1995 화학공학의이론과응용 Vol.1 No.2

이온 교환된 ZSM -22 촉매상에서 1- 부텐의 골격이성화 반응 특성에 관한 연구

백성현,이화영 ( Sung Hyeon Baeck,Wha Young Lee ) 한국화학공학회 1995 화학공학의이론과응용 Vol.1 No.1

BiOCl이 첨가된 Li2CO3-Sm2O3 촉매상에서 메탄의 Oxidative Coupling 반응

백성현 ( Sung Hyeon Baeck ),정진석 ( Jin Suk Chung ),이화영 ( Wha Young Lee ) 한국화학공학회 1998 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.36 No.3

환원법에 의한 직접 메탄올 연료전지(DMFC)용 Pt-Bi/Carbon 전극제조

김관성 ( Kwan Sung Kim ),김민경 ( Min Kyung Kim ),노동균 ( Dong Kyun Noh ),탁용석 ( Yong Sug Tak ),백성현 ( Sung Hyeon Baeck ) 한국공업화학회 2011 공업화학 Vol.22 No.5

다양한 비율의 Pt와 Bi를 carbon black (Vulcan XC-72R)에 담지시킨 Pt-Bi/C 촉매를 환원법을 이용하여 합성하였다. Pt와 Bi의 전구체로는 염화백금산(H2PtCl6 ·xH2O)과 비스무스트리질산(Bi(NO3)3 ·5H2O) 수용액을 각각 사용하였으며, 금속을 carbon에 담지하기 전, 금속물질의 분산도를 높여주기 위해 열처리와 산처리를 수행한 carbon black을 사용하였다. XRD (X-ray Diffraction) 분석과 XPS (X-ray Photoelectron Spectroscopy) 분석을 통하여 Pt-Bi/C 촉매 내에 Pt와 Bi가 소성 시키기 전에는 BiPt 혹은 Bi2Pt로 존재하지만 500 ℃에서 소성을 한 후에는 Pt 격자구조 안으로 Bi가 침투하여 alloy을 형성하는 것을 확인하였다. 합성한 전극의 메탄올 산화반응은 전기화학분석장치(Potentiostat; Princeton applied research, VSP)를 사용하여 0.5 M CH3OH와 0.5 M H2SO4의 혼합수용액에서 순환전압법(cyclic voltammetry, CV)을 이용해 측정하였다. 메탄올 산화에 대한 전기화학적 촉매 활성을 평가한 결과 적절한 양의 Bi를 첨가한 경우, 메탄올 산화반응에 대한 높은 촉매활성을 나타냄을 확인하였다. 메탄올 산화에 대한 활성은 전극과 전해질 사이의 안정성과 밀접한 관련이 있다. 정전압법(Chronoamperometry, CA)을 이용하여 전극의 안정성을 평가한 결과 메탄올 산화반응에 높은 활성을 나타내는 촉매일수록 전극의 안정성도 높은 것을 확인하였다. Pt-Bi/C catalysts supported on carbon black with various Pt/Bi ratios were synthesized by a reduction method. Chloroplatinic acid hydrate (H2PtCl6 ·xH2O) and bismuth (III) nitrate pentahydrate (Bi(NO3)3 ·5H2O) were used as precursors for Pt and Bi, respectively. Before loading metal on carbon, heat treatment and pretreatment of carbon black in an acidic solution was conducted to enhance the degree of dispersion. The physical property of the synthesized catalysts was investigated by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern of untreated Pt-Bi/C catalyst showed BiPt and Bi2Pt peaks in addition to Pt peaks. These results imply that Bi atoms were incorporated into the Pt crystal lattice by Pt-Bi alloy formation. The catalytic activity for methanol oxidation was measured using cyclic voltammetry in a mixture of 0.5 M H2SO4 and 0.5 M CH3OH aqueous solution. The addition of proper amount of Bi was found to significantly improve catalytic activity for methanol oxidation. The catalytic activity for methanol oxidation was closely related to the stability between electrode and electrolyte. In order to investigate the stability of catalysts, chronoamperometry analysis was carried out in the same solution at 0.6 V.

초음파를 이용한 PVA에 의한 다중벽 탄소나노튜브의 수상 그래프팅

김영선(Yeong Seon Kim),백성현(Sung Hyeon Baeck),심상은(Sang Eun Shim) 한국고분자학회 2014 폴리머 Vol.38 No.3

초음파를 이용한 수중 반응을 통하여 친수성 고분자인 poly(vinyl alcohol) (PVA)를 다중벽 탄소나노튜브 표면에 개질하였다. 초음파 인가 시 PVA는 라디칼을 지닌 상태로 절단되며 탄소나노튜브는 일반적으로 라디칼 스캐빈저 역할을 하므로 생성된 PVA 라디칼과 반응하여 PVA 사슬이 탄소나노튜브 표면에 그래프트 된다. PVA의 그래프트 반응을 조절하기 위하여 초음파 인가 조건을 300과 500 W로 선택하였으며, 인가 시간은 최대 50분으로 하였다. 탄소나노튜브 표면에 그래프트된 PVA는 FTIR, TGA, SEM, 및 TEM을 통하여 분석하였다. 또한 PVA로 개질된탄소나노튜브의 분산안정성을 분석하였다. 그래프트된 PVA의 양은 초음파의 인가 출력과 인가 시간에 비례하여 증가하였으며, PVA로 개질된 탄소나노튜브는 물 속에서 매우 안정적인 분산성을 보였다. Multiwall carbon nanotubes (MWCNTs) were modified with a water soluble polymer, poly(vinyl alcohol),PVA, using a simple ultrasonic wave in water. Under the irradiation of ultrasound, PVA chains were severed as macroradicalsand instantly grafted onto the surface of MWCNTs due to the radical scavenging effect of MWCNTs. To controlthe grafting PVA onto MWCNTs, the ultrasonication power and irradiation time were changed from 300 to 500 Wand from 10 to 50 min, respectively. The grafted PVA onto MWCNTs was confirmed by FTIR, TGA, SEM, and TEM. Dispersion stability of the modified MWCNTs was monitored by Turbiscan. The amount of grafted PVA on MWCNTsincreased with the increase in the sonication power and irradiation time. The grafted PVA on MWCNTs induced theimproved dispersion stability of the modified MWCNTs in water. These findings exhibit that ultrasound can be readilyused for the grafting polymer chains on MWCNTs.

고효율의 리튬/공기 이차전지 공기전극용 Mn_1+XCo_2-XO₄ 고용체 촉매 합성 및 분석

박인영,장재용,임동욱,김태우,심상은,박석훈,백성현,Park, Inyeong,Jang, Jaeyong,Lim, Dongwook,Kim, Taewoo,Shim, Sang Eun,Park, Seok Hoon,Baeck, Sung-Hyeon 한국전기화학회 2015 한국전기화학회지 Vol.18 No.4

$Mn_{1+X}Co_{2-X}O_4$ solid solutions with various Mn/Co ratios were synthesized by a combustion method, and used as cathode catalysts for lithium/air secondary battery. Their electrochemical and physicochemical properties were investigated. The morphology was examined by transmission electron microscopy (TEM), and the crystallinity was confirmed by X-ray diffraction (XRD) analyses. For the measurement of electrochemical properties, charge and discharge measurements were carried out at a constant current density of $0.2mA/cm^2$, monitoring the voltage change. Electrochemical impedance spectroscopy (EIS) analyses were also employed to examine the change in charge transfer resistance during charge-discharge process. $Mn_{1+X}Co_{2-X}O_4$ solid solutions showed enhanced cycleability as a cathode of Li/air secondary battery, and the performance was found to be strongly dependent on Mn/Co ratio. Among synthesized catalysts, $Mn_{1.5}Co_{1.5}O_4$ exhibited the best performance and cycleability, due to high charge transfer rate.

리튬/공기 이차전지의 충방전 특성과 사이클 특성에 미치는 탄소의 영향 고찰

최현아 ( Hyun A Choi ),고보경 ( Bo Kyung Ko ),심상은 ( Sang Eun Shim ),백성현 ( Sung Hyeon Baeck ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.4

Three different carbon blacks (Vulcan, Ketjen Black, and 1:1 mixture of the two) are used as cathode catalysts for a lithium/air secondary battery, and their electrochemical properties are investigated. The surface morphology change after discharge is examined using scanning electron microscopy (SEM), and the discharge products are analyzed using Fourier transform-infrared spectroscopy (FT-IR). In order to measure the electrochemical properties, the charge and discharge measurements are conducted at a constant current density of 0.2 mA/cm2, which monitors the voltage change. Electrochemical impedance spectroscopy (EIS) analyses are also performed in order to examine the change in the charge transfer resistance during the charge-discharge process. Compared with both the Ketjen black and Vulcan, the 1:1 mixture of the two carbon blacks exhibits the best performance as a cathode for the Li/air secondary battery, which results from a synergistic effect that exploits-both carbon blacks.

Preparation and Properties of Polypropylene/Thermoplastic Polyester Elastomer Blends

Yeong Gon Kim(김영곤),Yeongseon Kim(김영선),Jin Kyu Choi(최진규),Sung-Hyeon Baeck(백성현),Sang Eun Shim(심상은) 한국고분자학회 2017 폴리머 Vol.41 No.3

폴리프로필렌/열가소성 폴리에스터 엘라스토머(PP/TPEE) 블렌드를 제조하였다. 두 상의 상용성을 증가시키기 위하여 maleic anhydride-grafted polypropylene(MA-g-PP)를 배합 도중 첨가하였다. SEM을 통한 모폴로지 분석결과, 두 상은 상용성이 없었으며 MA-g-PP를 첨가한 결과 상용성이 발현되어 MA-g-PP가 효과적인 상용화제로 작용하였다. MA-g-PP를 첨가한 PP/TPEE 블렌드는 XRD 분석 결과 20.9° 피크의 강도가 증가하였으며 21.6° 피크는 점차적으로 감소하였다. 상용화제가 첨가된 경우의 기계적 물성 증가는 SEM 및 XRD의 분석 결과와 부합하였다. DSC 분석 결과, TPEE의 함량이 증가할수록 결정화도가 감소하였으며 MA-g-PP가 첨가된 경우 상용성으로 인하여 단일의 유리전이온도가 관찰되었으며 열적 안정성이 증가되었다. Polypropylene (PP)/thermoplastic polyester elastomer (TPEE) blends were prepared. To enhance the compatibility between the two phases, maleic anhydride-grafted polypropylene (MA-g-PP) was applied during melt-mixing. The morphology obtained from scanning electron microscopy (SEM) showed that TPEE was not miscible with PP, however, those of the PP/TPEE/MA-g-PP indicated that PP and TPEE turned to miscible because MA-g-PP served as an effective compatibilizer. The tensile tests confirmed that the tensile strength of the PP/TPEE blends decreased and the elongation increased with increasing TPEE content. The increase in tensile strength of the PP/TPEE/MA-g-PP blends was associated with the morphology shown by SEM and internal structure. X-ray diffraction (XRD) confirmed that compared to the PP/TPEE blend, the intensity of the 20.9° peak of the PP/TPEE/MA-g-PP increased and that of the 21.6° peak decreased gradually due to the MA-g-PP. In differential scanning calorimetry (DSC), the crystallinity (Xc) of the PP/TPEE blends decreased with increasing TPEE content. The PP/TPEE/MA-g-PP blends showed a single weak glass transition (Tg) peak due to the compatibility between the PP and TPEE. The thermal stability of the PP/TPEE blends with MAg-PP was also higher than that of the PP/TPEE.

환원법에 의한 직접 메탄올 연료전지(DMFC)용 Pt-Sn/Carbon 전극제조

정소미 ( So Mi Jung ),신주경 ( Ju Kyung Shin ),김관성 ( Kwan Sung Kim ),백성현 ( Sung Hyeon Baeck ),탁용석 ( Yong Sug Tak ) 한국공업화학회 2010 공업화학 Vol.21 No.5

금속물질의 분산도를 높여주기 위해 열처리와 산처리를 수행한 carbon black에 다양한 비율의 Pt와 Sn을 담지 시킨 촉매를 환원법을 이용하여 합성하였다. Pt/Sn의 비율은 전구체 용액 내에서 상대적인 농도를 변화시켜 조절하였으며, Pt/Sn 비율에 따른 반응 특성을 조사하였다. XRD (X-ray Diffraction) 분석을 통해 합성된 촉매의 결정도를 확인하였고, XPS (X-ray Photoelectron Spectroscopy) 분석으로 Pt와 Sn의 산화가를 확인하였다. 합성된 촉매의 조성과 구조를 분석하기 위해 SEM (Scanning Electron Microscopy)-EDS (Energy Dispersive Spectroscopy) 분석과 TEM (Transmission Electron Microscopy) 분석을 수행하였다. 산소 환원 반응 특성은 0.5 M H2SO4 수용액에서 RDE (Rotating Disk Electrode)를 이용하여 조사하였으며, 산소환원 촉매활성은 Pt/Sn의 비율에 크게 의존함을 확인하였다. 합성한 전극의 메탄올 산화반응은 전기화학분석장치(Potentiostat; Princeton applied research, VSP)를 이용하여 0.5 M CH3OH와 0.5 M H2SO4의 혼합수용액에서 수행하였다. 메탄올 산화에 대한 전기화학적 촉매활성과 안정성을 평가한 결과 적절한 양의 Sn을 첨가한 촉매가 높은 촉매활성과 안정성을 나타냄을 확인하였다. Pt-Sn with various ratios was supported on carbon black after pretreatment in an acidic solution by a reduction method. The Pt/Sn ratio was controlled by varying the concentration of each component in the solution, and the influence of the composition on the electrocatalytic activities was investigated. The crystallinity of the synthesized materials was investigated by XRD (X-ray Diffraction), and the oxidation states of both the platinum and tin were determined by XPS (X-ray Photoelectron Spectroscopy). SEM (Scanning Electron Microscopy)-EDS (Energy Dispersive Spectroscopy) was utilized to examine the morphology and composition of the synthesized electrode, and the particle size of the Pt-Sn was analyzed by TEM (Transmission Electron Microscopy). The electrocatalytic activity for oxygen reduction was evaluated in a 0.5 M H2SO4 solution using a rotating disk electrode system. The activity and stability were found to be strongly dependent on the electrode composition (Pt/Sn ratio). The catalytic activity and stability for methanol oxidation were also measured using cyclic voltammetry (CV) in a mixture of 0.5 M H2SO4 and 0.5 M CH3OH aqueous solution. The addition of proper amount of Sn was found to significantly improve both catalytic activity and stability for methanol oxidation.

열플라즈마를 이용한 질소도핑된 나노사이즈 TiO2의 광분해 특성

김민희 ( Min Hee Kim ),박동화 ( Dong Wha Park ),정영수 ( Young Soo Joung ),백성현 ( Sung Hyeon Baeck ) 한국공업화학회 2006 응용화학 Vol.10 No.1