바이폴라막은 양이온교환층과 음이온교환층 및 양극접합층으로 이루어진 이온교환막으로 물 분해 특성을 기반으 로 하여 프로톤과 수산화 이온을 생성시키는 막이다. 이러한 특성을 이용하여 화학 산업, 식품 가공, 환경 보호, 에너지 변환 및 저장과 같은 다양한 응용 분야에서 연구가 되고 있다. 본 논문에서는 바이폴라막 기술에 대한 종합적인 이해를 제공하기 위해 바이폴라막의 개념 및 물 분해 메커니즘과 물 분해 촉매에 대한 조사하였다. 마지막으로 최근 에너지 기술에 적용되고 있는 바이폴라막 프로세스를 조사하였다.

Pt/C catalysts were prepared using black carbon (CB), and evaluated for their potential application as a catalyst of liquid-phase catalystic exchange for tritium treatment. CB was treated with 10% H2O2 solution for 0 and 2 hours at 105°C, Ethylene glycol and 40wt% Pt were added to the dried treated sample to prepare a Pt/C catalyst. The physical and chemical properties of the prepared catalysts were evaluated by BET, XRD, elemental analysis (EA), and TEM analyses. As a result of BET analysis, the surface area of CB without 10% H2O2 was 237.2 m2·g-1, and after treatment with 10% H2O2, it decreased to 181.2 m2·g-1 for 2 hours. However, the internal surface area increased, indicating the possibility that more Pt could be distributed inside the CB treated with 10% H2O2. In the XRD analysis results, the presence of Pt was confirmed by observing the Pt peak in the prepared Pt/C catalyst, and it was also observed through TEM analysis that Pt was evenly distributed within the CB. The elemental analysis (EA) results showed that the ratio of S and N decreased and the ratio of O increased with increasing 10% H2O2 treatment time. The H2O2 treated carbon supported Pt catalysts and polytetrafluoroethylene were then loaded together on a foamed nickel carrier to obtain hydrophobic catalysts. Our hydrophobic Pt catalyst using H2O2 treated black carbon are expected to be usefully used in the tritium treatment system.

The carbon-containing molecule can be used as an NMR probe to explore the acidic and structural features of various catalytic materials. Thereinto, although mesityl oxide (MO) has been extensively employed to determine the acidity of solution and ionic liquid systems, could it be utilized to characterize the acidic properties of solid acid catalysts? In this work, on the basis of a series of isolated Brønsted and Lewis acid models with varied acid strengths, the adsorption configurations and corresponding 13C chemical shifts of adsorbed MO molecules have been comprehensively studied by means of a theoretical investigation approach. Among them, both the 13C chemical shift difference between β and α carbon atoms (Δδ), and the 13C chemical shift of β carbon atoms (δ13Cβ) in adsorbed MO molecules were explicitly demonstrated to be closely related to the intrinsic acid strength of Brønsted acid sites. These correlations could be utilized to quantitatively scale the Brønsted acid strength of solid acid catalysts. Besides, a moderate relationship was theoretically derived for the relevant 13C NMR parameters and intrinsic Lewis acid strength.

Mass production of high-quality carbon nanotubes (CNTs) remains a challenge, requiring the development of new wetimpregnated catalyst suitable for the catalytic chemical vapor deposition (CCVD) of CNTs in a fluidized bed reactor. For the successful development of a new catalyst, a highly robust system to synthesize CNTs must be established. Here, we systematically investigated the robustness of CNT synthesis by CCVD using a wet-impregnated catalyst. We statistically tested four factors that could potentially affect the robustness of CNT synthesis system, focusing on carbon yield and IG/ID. First, we tested the effect of vacuum baking before CNT growth. F test and CV equality test concluded that vacuum baking recipe did not significantly reduce the variability of the CNT synthesis. Second, we tested the batch-to-batch variation of catalysts. The results of t test and one-way analysis of variance indicate that there is significant difference in carbon yield and IG/ID among catalysts from different batches. Third, we confirmed that there is spatial non-uniformity of wet-impregnated catalysts within a batch when they are produced in large scale. Finally, we developed a multi-step heating recipe to mitigate the temperature overshooting during the CNT synthesis. The multi-step recipe increased the mean of carbon yield, but did not influence the variability of CNT synthesis. We believe that our research can contribute to the establishment of a robust CNT synthesis system and development of new wet-impregnated catalysts.

Ammonia is a potential fuel for producing and storing hydrogen, but its usage is constrained by the high cost of the noble metal catalysts to decompose NH3. Utilizing non-precious catalysts to decompose ammonia increases its potential for hydrogen production. In this study, carborundum (SiC)-supported cobalt catalysts were prepared by impregnating Co3O4 nanoparticles (NPs) on SiC support. The catalysts were characterized by high-resolution transmission electron microscope, X-ray photoelectron spectroscopy, temperature programmed reduction, etc. The results show that the large specific surface area of SiC can introduce highly distributed Co3O4 NPs onto the surface. The amount of Co in the catalysts has a significant effect on the catalyst structure, particle size and catalytic performances. Due to the interaction of cobalt species with SiC, the 25Co/SiC catalyst provided the optimal ammonia conversion of 73.2% with a space velocity of 30,000 mL gcat −1 h− 1 at 550 °C, corresponding to the hydrogen production rate of 24.6 mmol H2 gcat −1 min− 1. This research presents an opportunity to develop highly active and cost-effective catalysts for hydrogen production via NH3 decomposition.

An hydrogen adsorption study on graphene-based surfaces consisting of nitrogen-doped graphene and core–shell type catalysts of initially Pd13 , Pt13 , PdPt12 and PtPd12 core–shells, is presented in this work. Density functional theory results indicate correlation between charge transfer and structural properties, hydrogen adsorption energies, magnetic behavior and electronic properties. Reduction of hydrogen, together with higher values of charge transfer was observed for high hydrogen dissociation, compared to the case of non-hydrogen dissociation. In some cases, these values may be almost an order of magnitude larger than that of non-hydrogen dissociation. Hydrogen dissociation is also related to oxidation of the surface and correlates with a non-core shell-type structure, high adsorption energies and low magnetic moments, in general. Besides, core shell-type structure dramatically changes the magnetic and electronic properties of charge transfer. The results obtained in this work may provide important information for storing hydrogen.

To investigate the effect of the catalyst and metal–support interaction on the methane decomposition behavior and physical properties of the produced carbon, catalytic decomposition of methane (CDM) was studied using Ni/SiO2 catalysts with different metal–support interactions (synthesized based on the presence or absence of urea). During catalyst synthesis, the addition of urea led to uniform and stable precipitation of the Ni metal precursor on the SiO2 support to produce Ni-phyllosilicates that enhanced the metal–support interaction. The resulting catalyst upon reduction showed the formation of uniform Ni0 particles (< 10 nm) that were smaller than those of a catalyst prepared using a conventional impregnation method (~ 80 nm). The growth mechanisms of methane-decomposition-derived carbon nanotubes was base growth or tip growth according to the metal–support interaction of the catalysts synthesized with and without urea, respectively. As a result, the catalyst with Ni-phyllosilicates resulting from the addition of urea induced highly dispersed and strongly interacting Ni0 active sites and produced carbon nanotubes with a small and uniform diameter via the base-growth mechanism. Considering the results, such a Ni-phyllosilicate-based catalyst are expected to be suitable for industrial base grown carbon nanotube production and application since as-synthesized carbon nanotubes can be easily harvested and the catalyst can be regenerated without being consumed during carbon nanotube extraction process.

Ammonia is considered a promising hydrogen carrier due to its high hydrogen density and liquefaction temperature. Considering that the energy efficiency generally decreases as chemical conversion is repeated, it is more efficient to directly use ammonia as a fuel for fuel cells. However, catalysts in direct ammonia fuel cells have the critical issues of sluggish ammonia oxidation reaction (AOR) rate and poisoning of reaction intermediates. In particular, the use of precious metal as cathodic catalysts has been limited due to ammonia crossover and poisoning. In this study, we introduce Fe-based single-atom catalysts with selective activity for the oxygen reduction reaction (ORR) even in the presence of ammonia. As the Fe content increased, the single-atom structure of the catalysts changed into Fe nanoparticles or carbides. Among our Fe–N–C catalysts, FeNC-50 with a Fe loading amount of 0.34 wt% showed the highest ORR performance regardless of the ammonia concentration. In particular, the difference in activity between the catalysts increased as the concentration increased. The FeNC-50 catalyst showed remarkable stability after 1000 cycles. Therefore, we believe that single-atom dispersion is an important factor in the development of stable non-precious catalysts with high activity and inactivity for the ORR and AOR, respectively.

선택적 촉매 환원법(SCR)은 질소산화물(NOx)을 저감하는 매우 효율적인 방법으로 알려져 있으며 발생된 질소산화물(NOx)을 질 소(N2)와 수증기(H2O)로 환원시키는데 촉매 작용을 한다. 질소산화물(NOx) 저감 성능을 결정하는 요소 중 하나인 촉매는 셀 밀도가 증가하 면 촉매효율이 증가하는 것으로 알려져 있다. 본 연구에서는 실습선 세계로호에 설치되어 있는 발전 기관의 배기가스 조건을 모사한 실 험장치를 통하여 100CPSI(60Cell)촉매의 부하에 따른 질소산화물(NOx) 저감 성능을 확인하고 세계로호에 설치되어 있는 25.8CPSI(30Cell) 촉 매의 기존 연구 자료와의 비교를 통해, 셀 밀도가 질소산화물(NOx)의 저감에 미치는 영향에 대하여 고찰하였다. 실험용 촉매는 셀 밀도만 변화를 주었고 형태는 벌집형(honeycomb), 조성물질은 V2O5-WO3-TiO2를 동일하게 사용하여 제작하였다. 실험결과 100CPSI(60Cell) 촉매의 질소산화물(NOx) 농도 저감율은 평균적으로 88.5%이며 IMO specific NOx 배출량은 0.99g/kwh로 IMO Tier III NOx 배출기준을 만족하였다. 25.8CPSI(30Cell) 촉매의 경우, 질소산화물(NOx) 농도 저감율은 78%, IMO specific NOx 배출량은 2.00g/kwh 이었다 두 촉매의 NOx 농도 저감 율과 IMO specific NOx 배출량을 비교하였을 때, 100CPSI(60Cell)촉매가 25.8CPSI(30Cell) 촉매보다, NOx 농도 저감율은 10.5% 높고 IMO specific NOx 배출량은 약 2배 적은 것을 확인하였다. 따라서 촉매의 셀 밀도를 높임으로써 효율적인 탈질효과를 기대할 수 있으며 향후 실선 테스트를 통하여 검증한다면 촉매의 부피 저감을 통한 제작 비용을 줄이고 협소한 선박 기관실을 효율적으로 사용하기 위한 실용적 인 자료로서 기대된다.

Electrochemical reduction of carbon dioxide to valuable chemicals is a promising way of storing renewable energy through electric-to-chemical energy conversion, while its large-scale application is in urgent need of cheap and high-performance catalysts. Herein, we invent a convenient method to synthesize N-doped porous carbon by ammonia etching the pyrolysis carbon of petroleum pitch. We found the ammonia etching treatment not only increase the pyridinic-N content, but also enlarge the specific surface area of the petroleum pitch-based porous carbon. As a cheap and easily available catalyst for carbon dioxide electroreduction, up to 82% of Faradaic efficiency towards carbon monoxide was obtained at − 0.9 V vs the reversible hydrogen electrode in 0.1 M KHCO3. After a long time electrocatalysis of more than 20 h, the Faradaic efficiency of carbon monoxide remains 80%, indicating the porous carbon as made have an ultra-high stability as catalyst for carbon dioxide reduction. Our work provides a new technology to economically prepare efficient electrocatalysts for carbon dioxide reduction.

The poor durability issue of polymer electrolyte membrane fuel cells is a major concern in terms of their commercialization. To understand the degradation mechanism of the catalysts, an accelerated durability test (ADT) was conducted according to the protocol established by internationally accredited organizations. However, reversible and irreversible factors contributing to the loss of activity have not yet been practically segregated because of the limitations of a batch-type three-electrode system, leading to the misunderstanding of the deactivation mechanism. In this study, we investigated the effect of a fresh electrolyte on the ADT and recovery process. When the fresh electrolyte was used at every range of the cycle, the chances of incorrect detection of dissolved CO and Pt ions in the electrolyte were very low. When the same electrolyte was used throughout the test, the accumulated Pt ions were deposited on the surface of the Pt nanoparticles or carbon support, affording an increased electrochemical surface area (ECSA) of Pt. Therefore, we believe that periodic replacement by a fresh electrolyte or a continuous-flow electrolyte is essential for the precise determination of the structural and electrochemical changes in Pt/C catalysts.

Metal–organic frameworks (MOFs) are widely used as supports for single-atom catalysts (SACs) owing to their high specific surface area, porosity, and ordered metal–ligand structure. Their activity can be increased by increasing the number of electrochemically accessible active sites via the formation of atomically dispersed metal catalysts (M–Nx) that coordinate with nitrogen atoms on the MOF. Herein, we introduce the relationship between the size of the MOF as a starting material and the catalytic activity for the oxygen reduction reaction in alkaline media. The morphology and features of the MOFs are critically dependent on their size. Remarkably, cage-like MOFs below 33 nm are converted into collapsed structures and are connected between each MOF, even carbon fiber- or tube-like features, after carbonization. SACs derived from medium-sized MOFs exhibit excellent activity and are comparable to commercial Pt/C catalysts owing to their porous structure. Therefore, we believed that controlling the size of MOFs containing active atoms is an effective method of modulating the morphological properties of the support and even the number of active sites that are closely related to the activity.

Carbon-encapsulated Ni catalysts are synthesized by an electrical explosion of wires (EEW) method and applied for CO2 methanation. We find that the presence of carbon shell on Ni nanoparticles as catalyst can positively affect CO2 methanation reaction. Ni@5C that is produced under 5% CH4 partial pressure in Ar gas has highest conversions of 68 % at 350 oC and 70% at 400 oC, which are 73 and 75% of the thermodynamic equilibrium conversion, respectively. The catalyst of Ni@10C with thicker carbon layer shows much reduced activity. The EEW-produced Ni catalysts with low specific surface area outperform Ni catalysts with high surface area synthesized by solution-based precipitation methods. Our finding in this study shows the possibility of utilizing carbon-encapsulated metal catalysts for heterogeneous catalysis reaction including CO2 methanation. Furthermore, EEW, which is a highly promising method for massive production of metal nanoparticles, can be applied for various catalysis system, requiring scaled-up synthesis of catalysts.

Ni–Cr–Al metal-foam-supported catalysts for steam methane reforming (SMR) are manufactured by applying a catalytic Ni/Al2O3 sol–gel coating to powder alloyed metallic foam. The structure, microstructure, mechanical stability, and hydrogen yield efficiency of the obtained catalysts are evaluated. The structural and microstructural characteristics show that the catalyst is well coated on the open-pore Ni–Cr–Al foam without cracks or spallation. The measured compressive yield strengths are 2–3 MPa at room temperature and 1.5–2.2 MPa at 750oC regardless of sample size. The specimens exhibit a weight loss of up to 9–10% at elevated temperature owing to the spallation of the Ni/Al2O3 catalyst. However, the metal-foam-supported catalyst appears to have higher mechanical stability than ceramic pellet catalysts. In SMR simulations tests, a methane conversion ratio of up to 96% is obtained with a high hydrogen yield efficiency of 82%.

Activated carbon fibers (ACFs) were treated by electroless plating of CuO to improve their removal performance for volatile organic compounds (VOCs). The properties of these samples(CuO@ACFs) were evaluated by X-ray photoelectron spectroscopy (XPS), BET and N2O chemisorption to determine the area and dispersion of metallic CuO. The removal efficiency for benzene was investigated by gas chromatography (GC). The breakthrough time of CuO@ACFs increased by approximately 120% compared to that of untreated ACFs at benzene of 100 ppm. CuO@ACFs removed 100% of the benzene in 20 h, indicating this material can be used as a removal technology for VOCs.

The possibility of orange pulp utilization for nanoporous carbons production was investigated. Moreover, processing the obtained materials as limonene oxidation catalysts was studied as well. Limonene was separated from orange pulp obtained from fragmented orange peels—the waste from industrial fruits processing—by means of simple distillation. After the separation of limonene from the biomass, the dried orange pulp was converted to three types of nanoporous carbon catalysts: without activating agent, with NaOH, and with KOH. The catalysts were characterized by XRD, SEM, EDX, AFM, and sorption of N2 methods. The activities of the obtained catalysts were tested in the oxidation of limonene to perillyl alcohol (the main product), carveol, carvone, and 1,2-epoxylimonene and its diol. In the oxidation processes, hydrogen peroxide was used as the oxidizing agent. This work has shown for the first time that nanoporous carbons obtained from orange pulp waste, after separation of limonene, are active catalysts for limonene oxidation to industrially important value-added products.