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폴리다이메틸실록산 코팅을 통한 다결정성 UiO-66 분리막의 비선택적 결정립계 결함 캡핑
김익지,권혁택 한국청정기술학회 2023 청정기술 Vol.29 No.1
In general, the presence of non-selective intercrystalline (grain boundary) defects in polycrystalline metal-organic framework (MOF) or zeolite membranes, which are known to be ca. 1 nm in size, causes lower membrane performance (selectivity) than the intrinsically expected. In this study we show that applying a thin polymeric coating of polydimethylsiloxane (PDMS) on a polycrystalline MOF membrane is effective to cap the non-selective intercrystalline defects and therefore improve membrane performance. To demonstrate the concept, first, polycrystalline UiO-66, one of Zr-based MOFs, membranes were prepared by an in-situ solvothermal growth. By controlling membrane growth condition with respect to growth temperature, we were able to obtain polycrystalline UiO-66 membranes at 150 o C with intercrystalline defects of which the quantity is not significant, so it can be plugged by the suggested PDMS deposition. Second, their performances were compared before and after the PDMS deposition. As expected, the PDMS deposition ended up with a noticeable increase in CO2/N2 ideal selectivity from 6 to 14, indicating successful intercrystalline defect plugging. However, the enhancement in CO2/N2 selectivity was accompanied by a significant reduction in CO2 permeance from 5700 to 33 GPU because the PDMS deposition not only plugs defects but also forms a continuous coating on membrane surface, adding an additional transport resistance. 다공성 결정물질(예: 금속유기골격체(Metal-Organic Framework, MOF), 제올라이트(zeolite))로 만들어진 다결정성 분리막의 선택도는 일반적으로 크기가 1 nm 혹은 그 이상으로 알려진 비선택적 결정 간 결함, 즉 결정립계의 존재 때문에 저하된다. 본 논문에서는 다결정성 MOF 분리막 위에 폴리다이메틸실록산(polydimethylsiloxane, PDMS)의 코팅이 결정립계를 캡핑하여 분리막의 선택도를 향상시키는데 효과적임을 증명하였다. 제안된 개념을 증명하기 위해서 in-situ 용매열 합성법을 통해 제조된 지르코늄 기반의 MOF의 일종인 UiO-66 분리막 위에 PDMS를 코팅한 후, 코팅 전후의 성능변화를 관찰하였다. PDMS 코팅 후 UiO-66 분리막의 CO2/N2 단일 기체 분리 선택도는 6에서 14로 증가하였고, 동시에 CO2 투과도는 5700 GPU에서 33 GPU로 감소하였다. 선택도의 증가는 PDMS 코팅이 결정립계 결함을 효과적으로 메웠음을 의미하며, 동반된 투과도의 감소는 PDMS 코팅이 결함을 메우는 동시에 분리막 위에 연속적인 층을 형성하여 추가된 투과 저항에서 비롯되었다고 판단된다.
Metal-coated Polyether Ether Ketone Monopolar Plates for Polymer Electrolyte Membrane Fuel Cell
김민형,강윤식,박지윤,윤상권,성영은 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.12
For the polymer electrolyte fuel cell application, novel multilayer metal-coated polyether ether ketone (PEEK) monopolar plates were developed via electroless plating and electroplating process. The coating layers consisted of 7 µm thick Ni–P layer on a PEEK surface, 7 µm thick Cu layer on it, and 500 nm thick Au layer on the top surface. With metal-coated PEEK monopolar plates on both anode and cathode side, the current density of a single cell at 0.6 V was found to be 734 mA/cm2, which is about 85% using the conventional plates (869 mA/cm2).
Lilian Sarango,Lorena Paseta,Marta Navarro,Beatriz Zornoza,Joaquín Coronas 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.59 No.-
ZIF-8 and ZIF-67 particles, with sizes of 70 ± 10 nm and 240 ± 40 nm, respectively, were deposited by dip-coating on top of polyimide P84® asymmetric supports. In the best conditions, this gives rise to a MOF (metal-organic framework) monolayer which remains on the polyimide support during the interfacial polymerization of polyamide carried out to produce a thin film nanocomposite membrane for organic solvent nanofiltration (OSN). This method is simple, shorter and is environmentally friendly, since no excess MOF is lost during the interfacial polymerization, exhibiting good OSN results: dye rejection of 90% together with a high methanol permeance of 8.7 L m−2 h−1 bar−1.
이봉호,김종경,박찬호 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12
As the need for fuel cell systems increases, much research is underway to replace platinum catalysts. Therefore, non-precious metal catalysts composed of inexpensive metal have attracted attention. Along with catalyst development, the importance of electrode development is emphasized. In this study, two manufacturing methods using a commercial non-Pt catalyst (FeNC) for cathode were adopted to investigate the effect of the method on the performance of membrane electrode assembly (MEA) for polymer electrolyte membrane fuel cell (PEMFC). Additionally, the effect of different ionomer ratios in the catalyst slurry compositions on the electrode was studied. As a result, the MEA with cathode fabricated by the spray method displayed 2.87-times higher performance than that of MEA with cathode by gas diffusion electrode that is manufactured using the Doctor-blade method. The higher performance of the spray electrode is attributed to the large portions of the pores under 10 nm in the electrode estimated by the mercury intrusion porosimetry. Therefore, it is important to generate large numbers of mesopores to fabricate a high-performance electrode of the non-precious metal catalyst for PEMFC.
김병훈,나용한 한국세라믹학회 1995 한국세라믹학회지 Vol.32 No.10
When ceramic membrance was made from metal salt solution in place of metal akoxide solution, crack free and good adhesion to supporter was optimized for sol stability and good adhesion force. A starting sol was prepared from aluminum oxychloride aqueous solutjion in order to inhibit the grain growthof Al2O3 during heat treatment. The crack free dip coating can't be achieved in 1mol/ι zirconium oxychloride solution because of the high viscosity which interferes with the hydration copolymerization between Al3+ ion and Zr4+ ion. Thus Al2O3-ZrO2 sol stability and viscosity for dip coating was effective when 0.01 mol/ι zirconium oxychloride was added. The minimizing of crack and achieving better adhesion to the supporter wa obtained by microwave drying, surfactant addition and ultrasonic dip coating in wet atmosphere. The result seems to minimize the capillary force and improve the adhesive ability to supporter during the process. Where the average pore size of Al2O3-ZrO2 ultrafilter ceramic membrane measured 17 Å by the BET method and observed γ-Al2O3 phase with tetragonal zirconia after firing at 700℃.
고분저전해질 연료전지에서 TIN과 TIN이 코팅된 스텐레스 강 분리판의 부식 특성
한춘수 ( Choon Soo Han ),채길병 ( Gil Byung Chae ),이창래 ( Chang Rae Lee ),최대규 ( Dae Kyu,Choi ),심중표 ( Joong Pyo Shim ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.1
고분자전해질 연료전지용 분리판 소재로 스텐레스 강의 내식성과 전기전도성을 향상시키기 위해 표면을 TiN(titanium nitride) 또는 Ti/TiN(titanium/titanium nitride)으로 코팅하여 연료전지 운전환경에서 표면 코팅층의 물성 변화를 조사하였다. 200시간의 연료전지 운전에서 표면 코팅층의 부식, 균열(crack), 박리, 표면 화학조성 변화 등을 분석하여 코팅된 TiN 또는 Ti/TiN 박막의 역할을 규명하고자 하였다. 스텐레스 강 분리판의 전기전도도와 부식저항성은 소재 표면에 질화층 박막을 코팅함으로써 증가하였으나 연료전지 환경하에서 운전시 코팅된 박막의 부식과 박리현상이 SUS316L-Ti/TiN을 제외하고 현저히 발생하였다. TiN 코팅층과 하부 기재 사이에 Ti 중간층을 도입함으로써 TiN 박막의 밀착성이 향상되고 또한 코팅층의 두께 증가로 부식 위험성이 감소하는 것을 관찰하였다.