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Статті в журналах з теми "Catalyst ink":
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Lee, Seon-Ho, Seunghee Woo, Yun Sik Kang, Seokhee Park, and Sung-Dae Yim. "Evaluating Ink Structure Using Ultrasonic Spray Coating for PEMFC MEA." ECS Meeting Abstracts MA2023-02, no. 37 (December 22, 2023): 1739. http://dx.doi.org/10.1149/ma2023-02371739mtgabs.
Анотація:
From the standpoint of improving manufacturing productivity and performance/durability of PEMFC MEAs, there is an increasing interest in ink. Ink research is centered on comprehending the interplay between the components of the ink, including catalysts, ionomers, and solvents, to control the ink structure and evaluate its influence on ink properties, catalyst layer microstructure, and fuel cell performance. As a facet of this ink research, the current study proposes ultrasonic spray coating as a methodology to indirectly evaluate the ink structure. 50 wt% Pt/C catalysts loaded on Ketjenblack (KB) and Vulcan carbon (VC) were separately incorporated to produce sprayable inks with a solid content of 4 wt% using an Aquivion ionomer (EW 720) and a mixture solvent composed of a 1:1 weight ratio of 1-propanol and water. The structural differences between the two catalyst inks were compared by quantifying the amount of adsorbed and free ionomers, as well as their rheological properties. Additionally, the advantages of ultrasonic spray coating, such as the formation of small droplets on the order of tens of micrometers and rapid drying, were utilized to coat each ink onto a silicon substrate. The structural characteristics of the resulting catalyst layers were compared through SEM images, as well as the distribution of constituent elements using EDS and Auger spectroscopy. The Pt/KB catalyst ink forms a gel-like structure due to its relatively high amount of adsorbed ionomer, resulting in a relatively uniform distribution of catalyst particles and ionomers in the catalyst layer formed from ultrasonic spray droplets. In contrast, the Pt/VC catalyst ink behaves as a liquid-like, mainly existing in the form of free ionomer, regardless of ionomer content. During the drying process of each droplet, they merge to form larger unit catalyst layers, which exhibit an uneven distribution where free ionomers tend to concentrate at the edges of the catalyst layer due to the coffee-ring effect. As a result, the catalyst and ionomers exist in a non-uniform distribution, which is observed to affect the performance and electrochemical characteristics of fuel cells. In this presentation, we will discuss in detail the series of characteristics of ink-catalyst layer-fuel cell performance that vary according to catalyst properties.
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Liu, Guangxin, David McLaughlin, Simon Thiele, and Chuyen Pham. "Linking Multicomponent Interactions of Catalyst Ink and Catalyst Layer Fabrication with Electrochemical CO2 Reduction Performance." ECS Meeting Abstracts MA2023-01, no. 38 (August 28, 2023): 2238. http://dx.doi.org/10.1149/ma2023-01382238mtgabs.
Анотація:
The controllable fabrication of catalyst layers (CL) by tuning the multiscale structure formation is complex but vital to achieving optimum CO2 reduction (CO2R) performance. The CL formation is deeply influenced by catalyst ink. An in-depth understanding on the role of each catalyst ink component and how multicomponent interactions affect ink status, catalyst layer structure, and CO2R performance is crucial. In this work, the roles of various ingredients of catalyst ink were systematically investigated from simple binary inks to complete catalyst inks. Our results showed Ag agglomerates can be broken down more efficiently in water than in alcohols due to stronger inter-particle repulsive forces induced by water disassociation. Ag particles-Nafion networks were found to play a decisive role in stabilizing catalyst ink, mitigating agglomeration and particle sintering. The catalyst ink was comprehensively characterized and reported by static multiple light scattering (SMLS) for the first time in this study. The evolution of catalyst ink was identified in three stages: stable, flocculation and sedimentation. Isopropanol (IPA)-rich solvents were demonstrated to be more effective in stabilizing catalyst ink due to better dispersed Nafion aggregates and further enhanced Ag particle-Nafion interactions. Subsequently, catalyst layer structure and CO2R performance were correlated with multi-component interactions in catalyst ink. Strong Ag particle-Nafion interactions were proven to promote not only ink stability, but also catalyst layer homogeneity and reaction site distribution. Water-rich inks helped improve the porosity and durability of GDEs. The cathodic potential of GDEs made by 70%-water inks (-0.75 V vs. NHE) was 30% lower than zero-water inks (-1.1 V vs. NHE), and the highest CO selectivity was boosted to 97% at an industrial meaningful current density of 200 mA/cm2 by enhancing Ag particle-Nafion interactions through rational design of ink formulation, dispersing and fabrication processes. Simultaneously, a scalable manufacturing methodology of robust GDE was developed and validated to achieve optimal CO2R performance. It will not only provide a meaningful reference for lab applications (fast and reproducible GDE fabrication aiming at new catalysts, ionomers, membranes or operation conditions development), but also provide a steppingstone to industrial applications (GDE fabrication aiming at large scale, good durability and quality of conformance). Figure 1
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Du, Shaojie, Shumeng Guan, Shirin Mehrazi, Fen Zhou, Mu Pan, Ruiming Zhang, Po-Ya Abel Chuang, and Pang-Chieh Sui. "Effect of Dispersion Method and Catalyst on the Crack Morphology and Performance of Catalyst Layer of PEMFC." Journal of The Electrochemical Society 168, no. 11 (November 1, 2021): 114506. http://dx.doi.org/10.1149/1945-7111/ac3598.
Анотація:
The effects of dispersion method for ink preparation and types of catalyst on the catalyst layer’s structure and characteristics were investigated. Catalyst layers prepared by two dispersion methods, i.e., sonication and ball-milling, and two types of catalyst: Pt-HSC (High Surface Area) and Pt-Vulcan XC-72, were fabricated. Viscosity, particle size distribution of the catalyst inks, catalyst layer’s surface properties, and cell performance were measured. Experimental results with the Pt-HSC at ionomer/carbon weight ratio 0.8 show that ink dispersity strongly depends on the mixing method and large agglomerates form in the ink after sonication. The effect of the dispersion method on the ink prepared by Pt-Vulcan XC-72 at similar conditions is not noticeable. The catalyst layer’s mechanical properties, such as hardness and Young’s modulus, were found to vary widely. With an increase of catalyst layer thickness, the number of pin-holes decreased and cracks gradually increased in size. Polarization curves show that the membrane electrode assemblies (MEAs) made with 60% Pt-HSC have a better performance than those with 30% Pt-Vulcan XC-72. The performance and measured electrochemical active surface area of the MEAs made from both catalysts are slightly affected by dispersion method.
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Park, Jaehyung, Nancy N. Kariuki, and Deborah J. Myers. "In-Situ X-Ray Scattering Study of Iridium Oxide Catalyst for Polymer Electrolyte Membrane Water Electrolyzer during Ink Sonication and Drying Process." ECS Meeting Abstracts MA2022-02, no. 39 (October 9, 2022): 1420. http://dx.doi.org/10.1149/ma2022-02391420mtgabs.
Анотація:
Polymer electrolyte membrane water electrolyzers (PEMWEs) offer greenhouse gas emission-free hydrogen production for fuel cell vehicles and other industrial uses when using renewable energy sources [1]. Unsupported iridium oxide (IrO2) is the most active stable oxygen evolution reaction (OER) catalyst utilized in the anode of the PEMWE [2]. The atomic and microstructure of IrO2 catalysts and electrodes and interactions between and ionomer and catalyst can affect the ultimate performance of the PEMWE anode. These properties and phenomena may be controlled by the interactions of the ionomer in the catalyst-ionomer ink, by the effect of ink solvent composition on those interactions, and by the ink mixing and coating procedures. The microstructure evolution of the IrO2 catalyst during ink processing has not yet been identified. This presentation will describe relationships between ink formulation, electrode morphology, and performance for the IrO2-based PEMWE anodes. Moreover, the results of the evolution of the catalyst layer during the ink drying process as a function of solvent removal rate and solvent identity will be discussed. This study uses the in-situ technique of ultra-small angle X-ray scattering (USAXS) combined with small angle X-ray scattering to determine particle size distributions and the extent of IrO2 agglomeration in the inks and electrodes during the ink mixing/settling and drying processing. The effects of ionomer concentration, catalyst concentration, and solvent composition on the microstructure of the catalyst inks and electrode are correlated with the PEMWE performance and operando diagnostic data. Acknowledgements This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the H2NEW Consortium. This work was authored in Argonne National Laboratory, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357. This research used the resources of the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. References [1] M. Carmo, D. L. Fritz, J. Mergel, D. Stolten, A Comprehensive Review on PEM Water Electrolysis, Int. J. Hydrogen Energy 2013, 38, 4901−4934. [2] H. Yu, N. Danilovic, Y. Wang, W. Willis, A. Poozhikunnath, L. Bonville, C. Capuano, K. Ayers, R. Maric, Nano-size IrOx catalyst of high activity and stability in PEM water electrolyzer with ultra-low iridium loading, Applied Catalysis B: Environmental 2018, 239, 133-146.
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Sasabe, Takashi, Toshihiko Ogura, Koki Okada, Haruto Oka, Katsunori Sakai, and Shuichiro Hirai. "Influence of Ethanol Decomposition on Dispersion of PEFC Catalyst Ink." ECS Transactions 112, no. 4 (September 29, 2023): 93–99. http://dx.doi.org/10.1149/11204.0093ecst.
Анотація:
To achieve high power density operation of polymer electrolyte fuel cells (PEFCs), it is required to realize higher performance catalyst layer. Because dispersion structure of catalyst ink strongly affects the catalyst layer structure, it is crucial to understand the dispersion mechanism of PEFC catalyst ink. Though water/ethanol solution is used as solvent of the catalyst ink, decomposition of ethanol by Platinum catalyst strongly affect dispersion of the catalyst ink. In this study, influence of ethanol decomposition on dispersion of catalyst inks were investigated. Among the decomposition byproducts of ethanol, results of rheology characteristics and direct observation by scanning electron assisted dielectric microscopy clearly showed that acetaldehyde has a significant impact on aggregation of catalyst ink. To reveal the mechanism of aggregation, particle size measurement and ionomer adsorption fraction measurement of the catalyst ink were carried out. The results suggested that the acetaldehyde impede adsorption of the ionomer on Platinum catalyst.
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Khandavalli, Sunilkumar, Jaehyung Park, Robin Rice, Guido Bender, Deborah J. Myers, Michael Ulsh, and Scott A. Mauger. "Tuning the Rheology of Anode Inks with Aging for Low-Temperature Polymer Electrolyte Membrane Water Electrolyzers." ECS Meeting Abstracts MA2022-02, no. 40 (October 9, 2022): 1483. http://dx.doi.org/10.1149/ma2022-02401483mtgabs.
Анотація:
Low-temperature polymer electrolyte membrane water electrolyzers (PEMWE) are an attractive clean energy technology to produce hydrogen (H2), which is an energy carrier for several applications such as transportation and grid-scale energy storage and distribution (as supported by the US Department of Energy’s H2@Scale initiative). The catalyst layers -- composed of catalyst particles and ionomer, which acts as a binder for the catalyst and a proton conducting medium -- are key components of the PEMWE membrane electrode assembly (MEA). The catalyst layers are commonly fabricated by solution-processing an ink, which is a mixture of catalyst and ionomer often dispersed in a water-alcohol solvent mixture. Tuning the rheological properties of the anode inks (typically composed of iridium oxide catalyst, IrOx), particularly increasing their viscosity without significantly increasing the solids loading, to suit various scalable coating methods, is generally a challenge due to relatively low porosity and high density of the IrOx catalysts compared to the carbon-supported cathode catalysts. The typically low viscosities of the anode inks combined with high particle densities often cause stability/settling issues and challenges obtaining unform coatings, leading to inhomogeneous distribution of the catalyst that may have a negative effect on electrode performance. In this presentation we report on a dramatic enhancement in the viscoelasticity of the anode inks with aging, where the ink transitions from a liquid-like to a weak gel-like structure. The steady-shear and oscillatory shear rheology characterizations of the inks as a function of aging/time, the impact of formulation conditions (ionomer-to-catalyst ratio and dispersion media composition) on the viscoelastic enhancement with aging, and possible mechanisms for the observed behavior will be discussed. In addition to the rheological measurements, X-ray scattering characterization of the ink structure will be presented. The implications of the rheological changes on ink stability and processing will also be discussed. Additionally the impact of ink age on MEA performance will be presented.
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Sasabe, Takashi, Toshihiko Ogura, Koki Okada, Haruto Oka, Katsunori Sakai, and Shuichiro Hirai. "Influence of Ethanol Decomposition on Dispersion of PEFC Catalyst Ink." ECS Meeting Abstracts MA2023-02, no. 37 (December 22, 2023): 1740. http://dx.doi.org/10.1149/ma2023-02371740mtgabs.
Анотація:
To achieve high power density operation of polymer electrolyte fuel cells (PEFCs), it is required to realize high-performance catalyst layer with low oxygen transport resistance, high proton and electron conductivities, and high electrochemical surface area (ECSA) with low Platinum loading. Because dispersion structure of catalyst ink strongly affects porous structure of the catalyst layer, it is crucial for realization of high-performance catalyst layer to understand the dispersion mechanism of the catalyst ink. Our group has reported that decomposition of ethanol, as a solvent, by platinum catalyst significantly affects aggregation of the catalyst ink. [1, 2] But, the mechanism of the catalyst ink aggregation was not fully understood. In this study, effect of ethanol decomposition on the aggregation of the catalyst ink was investigated. The catalyst ink was fabricated by mixing platinum-supported carbon (TEC10V30E, Tanaka Kikinzoku), ionomer (DE1021, Sigma-Aldrich), and water/ethanol solvent (water/ethanol: 60/40 wt%). Decomposition product of ethanol within the catalyst ink solvent was analyzed by GC/MS (GCMS-QP2020NX, SHIMADZU), and presence of acetaldehyde (C2H4O) and acetic acid (CH3COOH) was detected. In order to investigate the influence of these products on aggregation of the catalyst ink, acetaldehyde or acetic acid was added to the catalyst ink. The particle size distribution was evaluated by using laser diffraction type particle size distribution meter (LA-960V2, HORIBA) without dilution, and it was confirmed that the acetaldehyde-added catalyst ink showed larger particle size and the acetaldehyde caused the aggregation of the catalyst ink (Figure 1). In addition, dispersion of the catalyst ink was observed by using an optical microscopy, and aggregation of the catalyst ink by adding the acetaldehyde was clearly observed (Figure 2). To understand the aggregation mechanism by adding acetaldehyde, ionomer adsorption fraction on the platinum-supported carbon was measured by using centrifugation method, and the decrease in ionomer adsorption fraction by adding acetaldehyde was confirmed. From these results, it was confirmed that acetaldehyde generated by the decomposition of ethanol in the catalyst ink leads to a decrease in the ionomer adsorption fraction. It is reported that the ionomer promotes the dispersion of platinum-supported carbon due to electrostatic repulsion forces, and it is suggested that the decrease in ionomer adsorption fraction results in the aggregation of the catalyst ink. Therefore, to realize high-performance catalyst layer, influence of acetaldehyde should be minimized and further research is requested to understand it. Acknowledgement This presentation is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). References [1] Takashi Sasabe et al., ECS Trans. 104, 191 (2021). [2] Takashi Sasabe et al., ECS Meeting Abstracts 242, 1433-1433 (2022). Figure 1
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Liu, Huiyuan, Linda Ney, Nada Zamel, and Xianguo Li. "Effect of Catalyst Ink and Formation Process on the Multiscale Structure of Catalyst Layers in PEM Fuel Cells." Applied Sciences 12, no. 8 (April 8, 2022): 3776. http://dx.doi.org/10.3390/app12083776.
Анотація:
The structure of a catalyst layer (CL) significantly impacts the performance, durability, and cost of proton exchange membrane (PEM) fuel cells and is influenced by the catalyst ink and the CL formation process. However, the relationship between the composition, formulation, and preparation of catalyst ink and the CL formation process and the CL structure is still not completely understood. This review, therefore, focuses on the effect of the composition, formulation, and preparation of catalyst ink and the CL formation process on the CL structure. The CL structure depends on the microstructure and macroscopic properties of catalyst ink, which are decided by catalyst, ionomer, or solvent(s) and their ratios, addition order, and dispersion. To form a well-defined CL, the catalyst ink, substrate, coating process, and drying process need to be well understood and optimized and match each other. To understand this relationship, promote the continuous and scalable production of membrane electrode assemblies, and guarantee the consistency of the CLs produced, further efforts need to be devoted to investigating the microstructure of catalyst ink (especially the catalyst ink with high solid content), the reversibility of the aged ink, and the drying process. Furthermore, except for the certain variables studied, the other manufacturing processes and conditions also require attention to avoid inconsistent conclusions.
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Sasabe, Takashi, Toshihiko Ogura, Koki Okada, Katsunori Sakai, and Shuichiro Hirai. "(Digital Presentation) Investigation on Effects of I/C Ratio on Dispersion Structure of PEFC Catalyst Ink By Scanning Electron Assisted Dielectric Microscopy." ECS Meeting Abstracts MA2022-02, no. 39 (October 9, 2022): 1433. http://dx.doi.org/10.1149/ma2022-02391433mtgabs.
Анотація:
To achieve high power density operation of polymer electrolyte fuel cells (PEFCs), it is required to realize higher performance catalyst layer with low oxygen transport resistance, high proton conductivity, and low Platinum loading. Because dispersion structure of catalyst ink strongly affects the catalyst layer structure, it is crucial to understand the dispersion mechanism of PEFC catalyst ink. We have reported that that solvent composition (ethanol concentration) of the catalyst ink strongly affect dispersion of the catalyst ink [1, 2], but effects of other components on the dispersion of the catalyst ink were not fully understood yet. In this study, effect of I/C ratio (amount of ionomer) on the dispersion of the catalyst ink was investigated. The catalyst inks were fabricated by mixing platinum-supported carbon (TEC10V30E, Tanaka Kikinzoku), ionomer (DE1021, Sigma-Aldrich), and water/ethanol solvent. To investigate the effect of ionomer on dispersion of the catalyst ink, solvent compositon (ethanol/water = 20/80 wt%), amount of the platinum-supported carbon and solid content of the catalyst ink were kept constant., and the I/C ratio was changed from 0.25 to 1.25. Viscosity characteristics were measured at each shear rate in the range of 0.01 to 1000 1/s by a rotary rheometer (MCR302, Anton-Paar), and particle size distribution of the catalyst ink was measured by the laser diffraction type particle size distribution meter (LA-960V2, HORIBA) without any dilution. In addition, we have succeeded to directly observe the dispersion structure of the catalyst ink by using a scanning electron assisted dielectric microscopy (SE-ADM) for the first time. SE-ADM enabled observation of the catalyst ink with very little radiation damage and high-contrast imaging without staining or fixation at an 8-nm spatial resolution, and distribution of the platinum-supported carbon, ionomer, and solvent were clearly observed. Figure (a) showed the effects of I/C ratio on aggregation size. The result clearly showed that the catalyst inks with too less (I/C=0.25) or too much (I/C=1.25) amount of ionomer were aggregated. Figure (b) showed the results of SE-ADM imaging. Because the dielectric constant of materials within the catalyst ink were different, the image clearly visualized distribution of the platinum-supported carbon, ionomer, and solvent, and the visualization results of the catalyst ink with different I/C ratio were consistent with the results of the particle size distribution measurement. Though the ionomer works as a surfactant within the catalyst ink, too much ionomer makes the dispersion of the catalyst ink worth, and tuning the amount of ionomer is important to realize the high performance catalyst layer. Acknowledgement This presentation is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). [1] Kaname Iida et al. 2020 ECS Trans. 98, 497. [2] Takashi Sasabe et al. 2021 ECS Trans. 104, 191. Figure 1
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Karaca, Ali, Andreas Glüsen, Klaus Wippermann, Scott Mauger, Ami C. Yang-Neyerlin, Steffen Woderich, Christoph Gimmler, et al. "Oxygen Reduction at PtNi Alloys in Direct Methanol Fuel Cells—Electrode Development and Characterization." Energies 16, no. 3 (January 19, 2023): 1115. http://dx.doi.org/10.3390/en16031115.
Анотація:
Catalyst layers made from novel catalysts must be fabricated in a way that the catalyst can function to its full potential. To characterize a PtNi alloy catalyst for use in the cathode of Direct Methanol Fuel Cells (DMFCs), the effects of the manufacturing technique, ink composition, layer composition, and catalyst loading were here studied in order to reach the maximum performance potential of the catalyst. For a more detailed understanding, beyond the DMFCs performance measurements, we look at the electrochemically active surface area of the catalyst and charge-transfer resistance, as well as the layer quality and ink properties, and relate them to the aspects stated above. As a result, we make catalyst layers with optimized parameters by ultrasonic spray coating that shows the high performance of the catalyst even when containing less Pt than commercial products. Using this approach, we can adjust the catalyst layers to the requirements of DMFCs, hydrogen fuel cells, or polymer electrolyte membrane electrolysis cells.
Дисертації з теми "Catalyst ink":
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Jacobs, Clayton Jeffrey. "Influence of catalyst ink mixing procedures on catalyst layer properties and in-situ PEMFC performance." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22932.
Анотація:
Despite the benefits of fuel cell technology its advancement to being commercially functional is hindered by a number of crucial factors. These factors are often associated with the lack of appropriate materials or manufacturing routes that would enable the cost of electricity per kWh to compete with existing technology. Whilst most research efforts have been directed towards developing more active catalysts, the amount of catalyst required in the fuel cell can be further reduced by improving the platinum utilisation in the membrane electrode assembly. The platinum utilisation is a strong function of the catalyst layer preparation step and there remains significant scope for optimisation of this step. Whereas significant work has been conducted into the different components of the catalyst ink there is limited work and understanding on the influence of the mixing method of the catalyst ink. This study will focus on the influence of the mixing technique on the catalyst ink properties and on the final fuel cell performance. Specifically, the study will investigate the effect of the three different mixing techniques on (i) catalyst ink quality (ii) the physical properties of the resultant catalyst layer and (iii) the in-situ electrochemical performance of the membrane electrode assembly. A large set of characterisation techniques were chosen to effectively study the step wise processing of the catalyst layer, and fuel cell performance. The results presented here include a comparison of the various mixing techniques and a comprehensive 2 x 2 factorial design into the individual techniques. The results suggest that high energy mixing is required for effective distribution of catalyst layer components, an even catalyst layer topography and a highly functional ionomer network which consequently, enhances performance. The mixing energy referred to involves prolonged mixing time, enhanced mixing intensity or a combination of the two. During bead milling of catalyst inks, high intensity mixing seems to be beneficial however, prolonged mixing time appears to be detrimental to the ionomer film structure. During high shear stirring and ultrasonic homogenisation of catalyst inks, the ink mixture significantly heats up. It has been observed that at higher temperatures, Nafion elongates and the contact with catalyst agglomerates is enhanced. High shear stirring of catalyst inks seems to be most effective at high agitation rates. High mixing energies result in high shear forces and in addition, high mixing temperatures which appear to be beneficial to establishing an effective catalyst/Nafion interface, enhancing the three phase boundary observed during in-situ testing. Ultrasonic homogenisation seems to be more effective at prolonged sonication times. Due to the erosive nature of ultrasonic dispersion, sufficient time is required to establish a well dispersed and distributed catalyst ink. However, the nature of particle size distribution resulting from ultrasonication shows that inks are unstable and is not recommended for high throughput processing. Overall, fuel cell performance is not significantly affected by the mixing step however; mixing does have an observable impact on catalyst layer formulation. Generally, when optimizing membrane electrode assembly fabrication, mixing parameters should be carefully chosen. This goes without saying that parameters need to be effectively studied before foregoing catalyst ink processing.
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DELMONDO, LUISA. "Development and characterization of nanostructured catalysts." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2709352.
Анотація:
The aim of this thesis work is focused on the development and characterization of nanostructured catalysts, in order to exploit them in two different reactions: the Oxygen Reduction Reaction (ORR) and the CO2 Reduction Reaction (CO2RR). The objective of this research is to find economical and ecological materials that could replace platinum as catalyst of the two reactions, while maintaining comparable
performance. Considering the ORR, the study is concentrated on the manganese oxide family (MnxOy), structured in the form of nanofibers by electrospinning technique and subsequent thermal treatment. The aim is to demonstrate that the MnxOy nanofibers own all the necessary properties, e.g. cheapness, efficiency and environmental-friendliness, revealing themselves as promising and innovative structures as catalysts for ORR. This material is studied in terms of morphology, composition and electrochemical activity by varying the final calcination temperature of the nanofibers. Thanks to this study, it is possible to describe the thermal evolution of the catalyst, comparing the electrochemical performance to a precise nanostructure and crystalline composition. The ceramic nanofibers, in fact, catalyze efficiently the ORR, granting a cheaper and more eco-friendly material than platinum, which is the most used today in energy production devices, as Microbial Fuel Cells (MFCs). The MnxOy catalyst is also coupled with a conductive substrate in an MFC device, revealing its capability of successfully reduce oxygen after the direct integration onto the electrode, without changing its catalytic performance. Considering the CO2RR, the attention is focused on the titanium dioxide nanotubes (TiO2 NTs) and copper oxide nanofibers (CuxO NWs) -based catalysts. Vertically oriented TiO2 NTs are obtained by anodic oxidation of a titanium foil and studied, by their own, in terms of morphology and composition. Further they are coupled with a copper and a copper oxide layers, characterizing the electrochemical properties, catalytic performance and selectivity toward CO2RR. As a competitive alternative to TiO2 NTs, CuxO NWs are obtained by thermally oxidizing the copper foils at different temperatures and characterizing them in terms of morphology,
composition catalytic activity and selectivity, analyzing both the liquid and gaseous byproducts. Lastly, the CuxO NWs are coupled with and titanium dioxide upper layer, exploiting the same in characterizations of the former substrate in order to be comparable. All the studied substrate show some catalytic activity toward CO2 reduction, but the highest efficiency is associated to the CuxO NWs, revealing formation of byproducts both in liquid and in gaseous form.
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Hepola, Jouko. "Sulfur transformations in catalytic hot-gas cleaning of gasification gas /." Espoo [Finland] : Technical Research Centre of Finland, 2000. http://www.vtt.fi/inf/pdf/publications/2000/P425.pdf.
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TOLOD, KRISTINE. "Visible light-driven catalysts for water oxidation: towards solar fuel biorefineries." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2732969.
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Baker, Jenny. "Development and characterisation of graphene ink catalysts for use in dye sensitised solar cells." Thesis, Swansea University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678272.
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ANNAMALAI, ABINAYA. "Electrochemical Energy Conversion Catalysts for Water Oxidation and CO2 Reduction." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1086344.
Анотація:
Numerous efforts have been made for the development of renewable energies to replace fossil fuels and thus reduce greenhouse gas emissions. Renewable energy has the advantage of having a limitless supply over time and is clean. This thesis reports on novel transition metal-based electrocatalysts for acidic water splitting and CO2 reduction, which are two significant technologies to produce chemical fuels (i.e. H2 and C-based compounds) from renewable electricity. The target is to develop and investigate cost-effective, stable, and efficient electrocatalysts for acidic water splitting and CO2 reduction, replacing noble metals and achieving performances above the current state of the art.
In the first part, the preparation and oxygen evolution properties of the oxygen plasma-treated and acid-activated carbon paper are investigated. This part also presents the Ru incorporated Carbon paper, as an efficient, stable, and self-standing catalyst for OER in acid. This catalyst shows an overpotential of 230 mV vs. RHE at 1 mA cm−2, comparable to the other carbon-based materials. It shows a small Tafel slope of 74 mV dec-1 and 20 hours of stability at 10 mA cm−2.
In the second part, the template-assisted wet synthesis and electrochemical OER studies of yolk-shell Co3O4/Co1−xRuxO2 hollow microspheres (MSs) are discussed. It demonstrates a lower overpotential of 240 mV at 10 mA cm-2 and a small Tafel slope of 70 mV dec−1. Also, the MSs exhibit high mass activity of 600 A g−1 and show high stability for 24 hours Chronopotentiometry tests at constant current densities of 10 and 20 mA cm−2 in 0.5 M H2SO4.
Finally, nanostructured CdSe/Cu3P/CdSe heterostructures (in the form of nanocoral and sandwiches), obtained through colloidal synthesis, were used as efficient electrocatalysts for CO2 reduction. The nanocoral and Sandwich structured catalyst demonstrated higher CO2-to- HCOO– conversion giving a FEHCOO– of about 60% and 40% at –1.4 V vs RHE, respectively in 0.5 M KCl.
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AMJAD, UM-E.-SALMA. "Noble Metal based Catalysts for Natural Gas Steam Reforming Activity, Endurance and Kinetics." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2588279.
Анотація:
This thesis illustrates catalytic activity, stability and intrinsic kinetics of methane steam reforming (MSR) reaction over noble metal catalysts. The main objective of this thesis is to evaluate a best performing catalyst based on the maximization of H2 production and minimization of CO in the synthesis gas produced from MSR reaction.
The noble metal catalysts tested towards MSR reaction were Rh, Ru and Pt supported on different reducible and irreducible oxides. The oxides (CeO2, MgO and Al2O3) used in this work were synthesized from their nitrite precursor by Simultaneous combustion synthesis (SCS) while Nb2O5 was prepared by heat treatment of Niobic acid obtained from Companhia Brasileira de Metalurgia e Mineracão (CBMM, Brasil). In all the catalysts the noble metals were deposited on the support by wetness impregnation method, except Pt/CeO2 which was prepared by one shoot SCS method. All the prepared catalysts were calcined under different calcination regimes. The best performing catalysts were characterized by different techniques BET, CO chemisorption, porosiometery, XRD, XPS, ICP, TEM and SEM analyses. Efforts have been made to correlate the catalytic activity with the physical characterization.
All the catalysts prepared were initially screened by MSR reaction in a tubular fixed bed quartz reactor of 4mm ID containing 30mg of catalyst diluted with 50mg of inert. For catalytic screening and stability test the feed was introduced at a weight hourly space velocity of 20 NLh-1g-1cat and steam to carbon ratio 3-4 depending upon the catalyst. The results obtained from basic screening of the catalysts were analyzed in terms of methane conversion, H2 produced in dry reformate and CO2 selectivity. Among all the catalysts tested towards MSR only two were chosen based on initial screening, Rh/CeO2 and Pt/CeO2, for the further test concerning catalyst stability.
The stability of Rh/CeO2 and Pt/CeO2 catalysts was determined based on daily start up and shut down cycle (DSS) with a 6h performance period. The Pt/CeO2 catalyst was tested for a total of 150 h in which 100h performance was with DSS in N2 environment while 50h of catalyst activity with DSS in reaction environment. The Rh/CeO2 catalyst was tested for a total of 25 h catalyst activity with DSS in N2 environment. Additionally the Rh/CeO2 catalyst was also tested in 100h continuous ageing. Both the catalysts showed good results in terms of catalyst activity and stability during the time period. As Rh/CeO2 catalyst showed good activity during 100h continuous endurance this catalysts was chosen to evaluate the intrinsic kinetics of methane steam reforming.
For the kinetics test firstly the heat and mass transfer limitations were evaluated both experimentally and theoretically. The reactor was operated in an integral mode and no inert was used in feed for the kinetic experiments. The effect of WHSV at constant S/C 3 on the methane conversion and product composition was also determined. The partial pressures of the reactants were varied by varying the steam-to-carbon ratio of the feed. An attempt was made to fit kinetic data obtained using the models available in literature. The kinetic data obtained was perfect fit for the model proposed by Berman, and the activation energy of Rh/CeO2 was found to be 38.6 kJ/mol.
8
PEZZOLATO, LORENZO. "Fe-N-C non-noble catalysts for applications in Fuel Cells and Metal Air Batteries." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2809320.
9
Turtayeva, Zarina. "Genesis of AEMFC (anion exchange membrane fuel cell) at the lab scale : from PEMFC’s inks composition toward fuel cell bench tests in alkaline media." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0285.
Анотація:
Les piles à combustible à membrane échangeuse d'anions (AEMFC) ont récemment attiré l'attention en tant que piles à combustible alternatives à faible coût aux piles à combustible à membrane échangeuse de protons traditionnelles en raison de l'utilisation possible d'électrocatalyseurs non-nobles. Bien que l'AEMFC ressemble à la PEMFC, les problèmes de gestion de l'eau sont plus prégnants dans une AEMFC car l'ORR en milieu alcalin nécessite de l'eau, tandis qu'en même temps, de l'eau est produite en grande quantité du côté de l'anode. Pour mieux comprendre la gestion de l'eau dans ce type de pile à combustible, il faut d'abord développer et acquérir de l'expérience avec ce type de pile à combustible à l'échelle du laboratoire. Puisque les matériaux prêts à l'emploi n'existaient pas au commencement de la thèse, nous avons dû fabriquer nos propres assemblages électrode-membranes (AMEs) à partir des matériaux disponibles dans le commerce. Etant donné que la thématique de fabrication des AMEs est nouvelle pour les chercheurs du LEMTA, cette thèse est articulée en deux parties, une dédiée à la formulation, la préparation et l'optimisation des AMEs pour PEMFC ; et une autre dédiée au développement d'AEMFC. Les résultats ont indiqué que la composition et préparation de l'encre, ainsi que la manière de déposer l'encre modifient systématiquement la structure de l'électrode, de même que ses performances en piles à combustible. En outre, l'étude fournit des informations sur les procédures et les méthodes pour les tests en AEMFC. Ici, nous souhaiterions partager notre savoir-faire avec les nouveaux venus dans le domaine de la préparation des AMEs pour piles à combustibles à membranes échangeuses d'ionsAnion exchange membrane fuel cells (AEMFCs) have recently attracted significant attention as low-cost alternative fuel cells to traditional proton exchange membrane fuel cells as a result of the possible use of platinum-group metal-free electrocatalysts. Although AEMFC is a mimic of PEMFC but working in an alkaline medium, water management issues are more severe in AEMFC because ORR in alkaline media requires water, while at the same time water is produced at the anode side. To better understand water management in this type of fuel cell, it is necessary first to develop and gain experience with this kind of fuel cell on the laboratory scale. Since no ready-to-use materials are available at the beginning of the project, the necessity of fabricating homemade MEAs from commercially available materials becomes a reality that we must face. As MEA fabrication is a new topic to LEMTA's researchers, this is why this thesis was divided into two parts: one part dedicated to the formulation, preparation, and optimization of MEAs for PEMFC through physico-chemical and electrochemical characterizations; another part dedicated to the development of AEMFC. The results indicated that ink deposition, composition, and preparation systematically change the electrode structure and thus affect fuel cells performance. Furthermore, the study provides information on the AEMFC procedures and methods. Here, we would like to share our know-how with newcomers in the field of preparation of MEA in ion exchange membrane fuel cells
10
ERCOLINO, GIULIANA. "Catalytic combustion of methane in lean conditions on Pd/Co3O4 : from powdered to open-cell foam supported catalysts." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2675699.
Анотація:
The aim of this work is an investigation on a series of Pd-doped cobalt spinels catalysts for the lean CH4 combustion reaction. All the catalysts were synthesized and fully characterized from the structural and surface point of view (XRD, XRF, RS, BET, XPS, and FESEM) and then tested towards the oxidation of CH4 in lean conditions. The work was divided into two parts. In the first part, different catalysts at powder level were screened to optimize the design of Pd-doped cobalt spinel catalysts. In the second part, the best performing Pd-based catalysts previously selected were coated on structures of various nature (ceramic monoliths and foams) and tested towards the lean methane combustion to simulate a possible real applications (abatement of unburned CH4 residues from compressed natural gas vehicles or ventilation air methane emissions in coal mines).
This thesis is organized as a collection of papers, either published during the Ph.D. or submitted for publications.
In the first part (catalysts at powder level), the influence of different synthesis methods on the preparation of Pd/Co3O4 catalysts was evaluated (Paper I). Next, the role of the Pd doping on Co3O4 was investigated to determine the optimal Pd loading (Paper II). Then the Pd/Co3O4 catalyst formulation was optimized: the important catalysts’ features determining the reactivity were exploited in a technologically relevant methane concentration range (Paper III). In the end, a series of cobalt iron spinels was investigated to synthesize active catalysts, with a lower content of Co, with the aim of reducing the production costs (Fe cheaper than Co) (Paper IV).
As main results, the synthesis method influences the catalytic activity. Indeed, the undoped spinels synthesized by solution combustion synthesis exhibit a better activity respect to the undoped spinel synthesized via precipitation. Thus, evaluating all the informations coming from the various characterizations, the influence of the synthesis method on the catalytic activity of cobalt oxide seems to be related with its redox state.
Palladium doping improves the catalytic activity independently of the synthesis method, palladium load, and CH4 inlet concentration. Indeed a complete CH4 oxidation can be reached at a temperature lower than 430 °C for undoped spinels. The addition of palladium led to the formation of a reduced cobalt oxide phase which could contribute to a generation of active oxygen species under reaction conditions. The optimal Pd load is 3wt.%, calculated as PdO. The benefit was due to the existence of well-dispersed Pd nanocrystals. At lower Pd concentrations (0.5% Pd) the amount of Pd was insufficient to catalyze CH4 combustion effectively in the applied conditions, while the specific activity was lost for higher Pd concentrations (5% Pd) because of the agglomeration of Pd nanoparticles.
Finally, the addition of Fe to Co3O4 did not affect the catalytic activity of undoped catalysts, supposedly because the rate-determining step of the reaction is the activation of the C–H bond in the CH4 molecule, and apparently, Fe is not influencing the lattice oxygen stability.
In the second part of the work, undoped and 3 wt.% Pd-doped cobalt spinel catalysts were deposited on monoliths and open cell foams via solution combustion synthesis using glycine as precursors. The catalyzed structures were impregnated with Pd via wetness impregnation. The catalytic activity were tested toward the methane oxidation in lean conditions, in a gas mixture containing 0.5 vol.% or 1 vol.% CH4 at three different weight hourly space velocity (30, 60, and 90 NL h–1 gcat–1). The addition of Pd improved the catalytic activity of all structures independently on the test conditions. The pressure drop and heat transfer properties were evaluated for monoliths and foams as well. The results show that the foams exhibit an higher catalytic activity than the monolith. Moreover, all the catalysts show better activity at lower weight hourly space velocity. The open cell foam based on zirconia, with the biggest average pore diameter, exhibits the best catalytic activity. In general, zirconia-based foams show a better activity than alumina and silicon carbide ones for all test conditions. In order to well understand the different behavior of the foams, pressure drop measurements and thermal conductivity tests were carried out. From these measurements, the zirconia-based foams have lower pressure drop and lower overall heat exchange coefficients than the monolith and alumina and silicon carbide foams. This aspect can be explained by the higher thermal conductivity of alumina and silicon carbide materials. In conclusion, the obtained results represent a promising scientific advance because they demonstrate the good and stable performance of a 3% Pd/Co3O4 catalyst on a zirconia-based structured support for methane combustion in adiabatic or quasi-adiabatic applications (Papers V and VI).
Finally, the basic Co3O4 spinel, synthesized with different methods, was tested as an alternative anodic catalyst for the electrochemical oxygen evolution reaction, the typical reaction of an electrolyzer (Paper VII).
Книги з теми "Catalyst ink":
1
Anderson, Laurie Halse. Catalyst. New York: Viking, 2002.
2
McCaffrey, Anne. Catalyst. New York: Random House Publishing Group, 2010.
3
Liedtka, Jeanne. The Catalyst. New York: Crown Publishing Group, 2009.
4
McCaffrey, Anne. Catalyst: A tale of the Barque cats. New York: Del Rey Ballantine Books, 2010.
5
Antrobus, Peggy. Womens' leadership: Catalysts for change. Toronto, ON: Ontario Institute for Studies in Education of the University of Toronto, Centre for Women's Studies in Education, 1998.
6
Palanithurai, G. Youth as catalysts and change makers. New Delhi: Concept Pub. Co., 2010.
7
Resta, Paul. Collaborative technologies as a catalyst for changing teacher practices. [Washington, DC]: U.S. Dept. of Education, Office of Educational Research and Improvement, Educational Resources Information Center, 1998.
8
Kiser, A. Glenn. Masterful facilitation: Becoming a catalyst for meaningful change. New York: AMACOM, 1998.
9
Penfield, Joyce. The media: Catalysts for communicative language learning. Reading, Mass: Addison-Wesley, 1987.
10
Bouchard, Pierrette. School success by gender: A catalyst for the masculinist discourse. [Ottawa]: Status of Women Canada, 2003.
Частини книг з теми "Catalyst ink":
1
Duan, Lunbo, and Lin Li. "Oxygen Carrier Aided Gasification (OCAG)." In Oxygen-Carrier-Aided Combustion Technology for Solid-Fuel Conversion in Fluidized Bed, 79–96. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-9127-1_5.
Анотація:
AbstractGasification is regarded as an effective clean utilization technology of solid fuel, which can convert the chemical energy of solid fuel into gaseous fuel. However, the primary gas products contain not only the essential gas products, but also an unacceptable amount of tars, which will cause operational problems such as blockage of downstream equipment during gasification. Catalysts are often used after the gasifier to catalyze tar in the pyrolysis product gas. However, the activity ofcatalysts generally declines over time, as they will be poisoned by prolonged exposure to an atmosphere containing elements such as sulfur, chlorine and alkali metals. In addition, under the condition of high tar content, carbon deposition may form on the surface of catalyst, which leads to the deactivation of catalyst. The oxygen carrier particles of natural ores not only can transport oxygen, but also contain various metal elements that can be used as catalysts for tar cracking. Introduce the OCs to replace inert bed materials may not only provide a cheap catalyst for the technology, but also complete the transfer of oxygen between the two reactors, this process is oxygen carrier aided gasification (OCAG).
2
Sachdeva, Garima, Dipti Vaya, Varun Rawat, and Pooja Rawat. "Solid-supported Catalyst in Heterogeneous Catalysis." In Heterogeneous Catalysis in Organic Transformations, 105–25. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003126270-5.
3
Fechete, Ioana, and Jacques C. Vedrine. "Nano-Oxide Mesoporous Catalysts in Heterogeneous Catalysis." In Nanotechnology in Catalysis, 57–90. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2017. http://dx.doi.org/10.1002/9783527699827.ch4.
4
Osazuwa, Osarieme Uyi, and Sumaiya Zainal Abidin. "Catalysis for CO2 Conversion; Perovskite Based Catalysts." In Advances in Science, Technology & Innovation, 297–310. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-72877-9_15.
5
Brazier, John B., and Nicholas C. O. Tomkinson. "Secondary and Primary Amine Catalysts for Iminium Catalysis." In Topics in Current Chemistry, 281–347. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/128_2008_28.
6
Brazier, John B., and Nicholas C. O. Tomkinson. "Secondary and Primary Amine Catalysts for Iminium Catalysis." In Topics in Current Chemistry, 281–347. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02815-1_28.
7
Pei, Guihong, Feng Yu, and Huafeng Fu. "Photocatalytic Properties of TiO2 in White Ink Wastewater and Its Recycling Using Printing and Dyeing Wastewater." In Advances in Transdisciplinary Engineering. IOS Press, 2023. http://dx.doi.org/10.3233/atde230385.
Анотація:
This paper mainly studies the white ink wastewater recycling of titanium dioxide pigment white ink wastewater’s titanium dioxide as a catalyst for photocatalytic degradation of dyeing wastewater Chroma. Through selecting the mixing ratio of white ink printing and dyeing wastewater and waste water, pH, illumination time and the type of coagulant four factors, each factor selected five levels of single factor experiments, and ultimately determined the optimal experimental conditions; it was found by a single factor, factors like the ratio of two kinds of water, pH, illumination time have a greater impact on the removal of the mixed water samples CODCr and Chromaticity. This paper chooses the above three factors set three levels of factors do three factors and three levels orthogonal experiment. Multivariate orthogonal experiments results shown how the three factors influence on the color and CODCr removal rate. When the pH value is acidic, it is beneficial for the removal of CODCr, while when the pH value is alkaline, it is beneficial for the removal of chroma. The single factor and multi-factor experimental results indicated that the CODCr content of wastewater is high and difficult to degrade. In this study, the highest CODCr removal rate was set as the optimal experimental conditions. The mixing ratio of white ink printing and dyeing wastewater to wastewater was 1:1, the pH value was 1, and the illumination time was 60 minute. Under these conditions, the chromaticity of mixed wastewater is reduced from 1000 times to 500 times, and the removal rate is 50%; The discarded titanium dioxide pigment has good photocatalytic activity and can be used as a catalyst to remove color printing and dyeing wastewater.
8
Shao, Z., and Y. H. Deng. "2.1.1 General Principles of Metal/Organocatalyst Dual Catalysis." In Dual Catalysis in Organic Synthesis 2. Stuttgart: Georg Thieme Verlag, 2020. http://dx.doi.org/10.1055/sos-sd-232-00002.
Анотація:
AbstractMetal/organocatalyst dual catalysis is a privileged catalytic strategy which involves both a metal-based catalyst and an organocatalyst to catalyze the organic transformation. Based on the type of activation of substrates with both catalysts, there are seven kinds of dual catalysis; namely cooperative catalysis, cascade catalysis, sequential catalysis, double activation catalysis, restorative catalysis, bifunctional catalysis, and multiple relay catalysis. The generic activation of the metal-based catalyst and the organocatalyst applied in the dual-catalytic system is summarized. In these dual-catalytic approaches, the advantages of both metal catalysis and organocatalysis are converged to achieve many transformations that were previously inaccessible or challenging by any single-catalyst paradigm, to develop new reactions, to discover unique reaction mechanisms, and even to allow for stereodivergent synthesis.
9
Yang, Yong. "Cellulose Acetate." In Polymer Data Handbook, 79–87. Oxford University PressNew York, NY, 2009. http://dx.doi.org/10.1093/oso/9780195181012.003.0014.
Анотація:
Abstract Major Applications Textile fibers, cigarette filters, plastics for molding and extrusion, films for photography and recording tape, LCD display, drug release modifier, sheeting, lacquers, protective coatings for paper, metal, and glass, adhesive for photographic film, ink reservoirs for fiber tip pens, absorbent cloths, and wipes. Preparative Techniques Cellulose acetate is made from processed wood pulp (cellulose). The pulp is processed using acetic anhydride to form acetate flake from which products are made. Another technique for producing cellulose acetate involves treating cotton with acetic acid, using sulfuric acid as a catalyst.
10
Maskill, Howard. "Catalysis of organic reactions in solution by small molecules and ions." In Structure and Reactivity in Organic Chemistry. Oxford University Press, 1999. http://dx.doi.org/10.1093/hesc/9780198558200.003.0004.
Анотація:
This chapter focuses on the catalysis of organic reactions in solution by small molecules and ions. Catalysis is the enhancement of the rate of a reaction by a compound (the catalyst) not generally present in the chemical equation which describes the reaction. Normally, a catalyst remains unchanged by the chemical reaction it catalyzes. It brings about the rate enhancement by providing a reaction pathway additional to the one which occurs in its absence. This additional pathway will have its own rate law, and the total rate of reaction in the presence of the catalyst is the sum of the catalysed and uncatalyzed pathways. The chapter then looks at electrophile catalysis, specific acid catalysis, general acid catalysis, nucleophile catalysis, specific base catalysis, and general base catalysis. It also considers the Brønsted equation.
Тези доповідей конференцій з теми "Catalyst ink":
1
Bradford, Michael C., and Logan Preston. "Marker Ink Impact on Prototype Catalyst Performance." In Automotive Technical Papers. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2018. http://dx.doi.org/10.4271/2018-01-5009.
2
Suzuki, Takahiro, and Shohji Tsushima. "PARTICLE TRANSFER AND STRUCTURE FORMATION IN CATALYST INK DURING DRYING PROCESS." In International Heat Transfer Conference 16. Connecticut: Begellhouse, 2018. http://dx.doi.org/10.1615/ihtc16.mtr.024076.
3
Rajalakshmi, N., R. Rajini, and K. S. Dhathathreyan. "High Performance Polymer Electrolyte Membrane Fuel Cell Electrodes." In ASME 2004 2nd International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2004. http://dx.doi.org/10.1115/fuelcell2004-2484.
Анотація:
Several methods are being attempted to improve the performance of PEM Fuel cell electrodes so that the cost of the overall system can be brought down. The performance can be improved if the utilization of the catalyst in the electrode increases. One of the early successful method was to add a proton conducting polymer, such as NafionR to the catalyst layer. However there is a limit to the amount of NafionR that can be added as too much NafionR affect the gas diffusion. The other method is to increase the surface area of the catalyst used which has also been adequately demonstrated. Alternative methods for providing increased proton conductivity and catalyst utilization are thus of great interest, and a number of them have been investigated in the literature. One method that is being extensively investigated is to introduce the catalyst onto the polymer electrolyte membrane followed by lamination with gas diffusion electrode. In the present work, we have carried out two methods i) screen print the catalyst ink on the NafionR membrane ii) catalyze the NafionR membranes by reducing a suitable platinum salt on the membrane. Standard gas diffusion electrodes were then laminated onto this membrane. The performances of Membrane Electrode Assemblies (MEAs) prepared by these routes have been compared with the commercially available Gore catalysed membrane. It was observed that catalysed NafionR membranes show a better performance compared to the catalyst ink screen printed on the NafionR membrane and commercial Gore membrane under identical operating conditions. However MEAs with Gore membrane give a better performance in the iR region compared to the other MEAs prepared using NafionR membrane. The lesser performance with Gore membrane is probably due to the limitations in the lamination method employed.
4
Hoffman, Casey J., and Daniel F. Walczyk. "Direct Spraying of Catalyst Inks for PEMFC Electrode Manufacturing." In ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54416.
Анотація:
Automated manufacturing techniques are needed to reduce production costs for polymer electrolyte membrane (PEM) fuel cell electrodes. The work presented in this paper focuses on the use of a low pressure, low volume direct spray valve that uses air pressure to atomize fluids and transfer them to a gas diffusion layer (GDL) to produce a gas diffusion electrode (GDE). Two of these electrodes would then be joined with a polymer electrolyte membrane to produce a fuel cell membrane electrode assembly (MEA). Accurate and reproducible deposition methods such as this will result in less wasted materials, especially platinum, and increased throughput compared to common laboratory-scale techniques such as paint brushing and Mayer-rod coating. In this study, the production of inks will be discussed including a catalyst ink containing platinum nano-particles supported on carbon (20% loading by weight) and a similar analog ink which is identical except for that it does not contain the platinum. Two different substrates, mylar transparency film and actual carbon paper GDL substrate will be used and presented in this study. Ink rheology (viscosity, solids content, etc.) will also be discussed as it pertains to optimizing spray pattern uniformity and process efficiency. Initial results of thickness measurements which are used for determining uniformity and the required overlapping of multiple coats will be presented. In addition, a comparison of scanning electron microscopy (SEM) images of electrode surface structures prepared by mayer-rod and spraying will be shown. A brief discussion of the future work planned by the authors in order to study the effects of processing variables on actual fuel cell performance will also be given.
5
Koraishy, Babar M., Sam Solomon, Jeremy P. Meyers, and Kristin L. Wood. "Parametric Investigations of Direct Methanol Fuel Cell Electrodes Manufactured by Spraying." In ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54824.
Анотація:
Manufacture of fuel cell electrodes by the thin-film method was originally proposed by Wilson et al. [1, 2] for proton-exchange membrane fuel cells (PEMFCs). This technology was subsequently utilized for the manufacture of direct methanol fuel cell (DMFC) electrodes by Ren et al. [3]. Key processing steps in the thin-film process are catalyst ink formulation and its application. The catalyst ink is typically composed of supported or unsupported catalysts, binder (ionomer), solvents and additives. Rheological properties of the ink, amount of binder, and choice of solvents are tuned to match the particular ink application process used to fabricate the electrode, as each coating process has its own unique requirements. Besides affecting the coating process, the choice and ratios of these components can significantly affect the electrochemical performance of the electrode. In this study, catalyst inks are designed and investigated for the spraying process, for utilization in the continuous fabrication of DMFC electrodes. For this purpose, the effect of the binder (ionomer) content on the performance of the electrodes is studied in detail. Decal-transfer electrodes are fabricated on a custom-built automated spraying apparatus with individually specified anode and cathode binder contents, and assembled to form a catalyst coated membrane (CCM) type membrane electrode assembly (MEA). These electrodes are rigorously tested to specifically identify their electrochemical performance, catalyst utilization and electrode morphology.
6
Hollinger, Adam S., and Paul J. A. Kenis. "Electrohydrodynamic-Jet Deposition of Pt-Based Fuel Cell Catalysts." In ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2016 Power Conference and the ASME 2016 10th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fuelcell2016-59454.
Анотація:
Fuel cell electrodes are traditionally fabricated by hand-painting or spraying a catalyst ink onto a gas diffusion electrode or membrane. However, electrodes prepared via these techniques do not always have a uniform distribution of catalyst. Recently, electrohydrodynamic-jet (e-jet) printing has been developed as a method to deposit a variety of chemical and biological materials with excellent precision for various applications in electronics, biotechnology, and microelectro-mechanical systems. Here we demonstrate e-jet deposition of Pt-based fuel cell catalysts as a technique for achieving uniform catalyst distribution on microelectrodes. E-jet deposition is studied as a function of applied potential, and at 450 V, printed catalyst lines are very uniform at ∼10 μm in width. For electrode areas less than 1 mm2, deposition times are on the order of a few hours, which compares well with traditional hand-painting deposition times. Uniform catalyst distribution is important to reducing catalyst loading, and the deposition technique presented here shows significant possibility to produce electrodes with high uniformity.
7
Wang, Po-Chiang, Yan-Yu Nian, Zhi-Yu Luo, Chang-Pin Chang, Yih-Ming Liu, and Ming-Der Ger. "The inkjet printing of catalyst Pd ink for selective metallization apply to product antenna on PC/ABS substrate." In 2013 8th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT). IEEE, 2013. http://dx.doi.org/10.1109/impact.2013.6706682.
8
Hess, Katherine C., William K. Epting, and Shawn Litster. "In Situ Measurements of Through-Plane, Ionic Potential Distributions in Porous Electrodes." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33169.
Анотація:
We present a novel apparatus for gathering in situ measurements of through-plane, ionic potential distributions in the porous electrodes of a polymer electrolyte membrane (PEM) fuel cell. Our diagnostic method uses a micro-structured electrode scaffold (MES) that is comprised of alternating layers of insulating and sensing materials into which a 100 μm diameter hole is micro-milled and then filled with catalyst ink. Using the MES, we performed a polarization curve experiment where the ionic potential was measured within a 50 μm thick catalyst layer at 8 and 24 μm from membrane. Our results show that there are significant ionic potential variations within the electrode. Such data is valuable in the electrochemical characterization of electrodes and catalysts. The MES potential measurements also provide insight into reaction distributions across the thickness of the electrode, which is valuable in the validation of porous electrode models.
9
Engle, Robb. "Maximizing the Use of Platinum Catalyst by Ultrasonic Spray Application." In ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54369.
Анотація:
The following discusses the method and advantages of ultrasonic deposition of carbon-based platinum ink solution onto catalytic membranes in the manufacture of platinum-based fuel cells, doubling industry standard performances. Using patented ultrasonic atomization technology, conductive properties are compared to those of films created with hydraulic deposition and paste printing methods, using comprehensive analysis of morphology characteristics, deposition density, and distribution of platinum particles throughout the thickness and surface area of the coating. Results indicate significant increase in uniform distribution of platinum particles using the ultrasonic deposition method. Measured electrochemically active Pt surface area using ultrasonic atomization was recorded as high as 71% of the total Pt particle surface area.
10
McGrath, Kimberly, and Douglas Carpenter. "Improved Electrocatalytic Activity of Oxygen Reduction on Platinum Using Nano-Cobalt in Direct Methanol Fuel Cell Cathode Electrodes." In ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97198.
Анотація:
High surface area nanometal particles of nano-cobalt (n-Co) (approx 8 nm particles), produced at QuantumSphere Inc., were blended in various ratios with Pt and Nafion® ionomer, and investigated for their electrocatalytic activity in the oxygen reduction reaction (ORR). The ORR was evaluated by voltammetry using Pt/n-Co blended catalyst on glassy carbon to determine both kinetic activity and as an indicator of direct methanol fuel cell (DMFC) cathode performance. Kinetic enhancement was observed for Pt:n-Co where n-Co is 30–50% (by weight) of the catalyst mixture, including a minimum of 10 mV improvement in the open circuit voltage (OCV). By Tafel slope measurements, it is clear that the mechanism for ORR does not change, however the reaction rate is enhanced by addition of n-Co to Pt in the catalytic ink. For ink compositions similar to those used for standard DMFC cathodes, eliminating 50% of the Pt black resulting in 50% higher energy density while reducing total catalyst cost by roughly 44%.
Звіти організацій з теми "Catalyst ink":
1
Olsen, Daniel, Bryan Hackleman, and Rodrigo Bauza Tellechaea. PR-179-16207-R01 Oxidation Catalyst Degradation on a 2-Stroke Lean-Burn NG Engine - Washing. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), May 2019. http://dx.doi.org/10.55274/r0011586.
Анотація:
Oxidation catalysts are often utilized to reduce carbon monoxide, formaldehyde, and volatile organic compounds in order to meet emissions regulations for large bore natural gas engines. These catalysts degrade over time and need to be replaced or regenerated to maintain emissions compliance. This work evaluates the effectiveness of catalyst regeneration, or catalyst washing. The evaluation is performed by utilizing field and laboratory slip streams combined with catalyst module performance (reduction efficiency) measurements and catalyst material surface analysis to quantify catalyst poisons.
2
Stevens and Olsen. PR-179-12214-R01 CO Sensor Experimental Evaluation for Catalyst Health Monitoring. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), September 2014. http://dx.doi.org/10.55274/r0010827.
Анотація:
Oxidation catalysts and three-way catalysts can be used to reduce the amount of CO present in engine exhaust. For 2-stroke lean-burn engines, the oxidation catalyst degrades over time be-cause of the buildup of poisons such as sulfur, zinc, phosphorous, and calcium. Three-way cata-lysts used with stoichiometric engines also degrade over time. Emissions analyzers are often used to evaluate the degradation of oxidation catalysts and three-way catalysts, but it can be very time consuming and expensive. Ideally, a simple sensor system would be beneficial for operating companies to determine if the catalyst were out of compliance according to normal operating standards. An ECM CO sensor and recording device was acquired for testing. The CO sensor system was evaluated for its ability to monitor post-catalyst CO concentration. The results show that this CO sensor system is ineffective at monitoring post-catalyst CO concentration.
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Badrinarayanan and Olsen. PR-179-11201-R01 Performance Evaluation of Multiple Oxidation Catalysts on a Lean Burn Natural Gas Engine. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), August 2012. http://dx.doi.org/10.55274/r0010772.
Анотація:
Two-way catalysts or oxidation catalysts are the common after-treatment systems used on lean burn natural gas engines to reduce CO, VOCs and formaldehyde emissions. The study evaluates the performance of oxidation catalysts from commercial vendors for varying catalyst temperature and space velocity. For this study, a part of the exhaust from a Waukesha VGF-18 GL lean burn natural gas engine was flowed through a catalyst slipstream system to assess the performance of the oxidation catalysts. The slipstream is used to reduce the size of the catalysts and to allow precise control of temperature and space velocity. Analyzers used include Rosemount 5-gas emissions bench, Nicolet Fourier Transform Infra-Red spectrometer and HP 5890 Series II Gas Chromatograph. The oxidation catalysts were degreened at 1200oF (650oC) for 24 hours prior to performance testing. The reduction efficencies for the emission species varied among the oxidation catalysts tested from different vendors. Most oxidation catalysts showed over 90% maximum reduction efficiencies on CO, VOCs and formaldehyde. VOC reduction efficiency was limited by poor propane emission reduction efficiency at the catalyst temperatures tested. Saturated hydrocarbons such as propane showed low reduction efficiencies on all oxidation catalysts due to high activation energy. Variation in space velocity showed very little effect on the conversion efficiencies. Most species showed over 90% conversion efficiency during the space velocity sweep. Adding more catalyst volume may not increase the reduction efficiency of emission species. Varying cell density showed very little effect on performance of the oxidation catalysts. The friction factor correlation showed the friction factor for flow through a single channel is inversely proportional to cell density.
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Olsen and Neuner. PR-179-12207-R01 Performance Measurements of Oxidation Catalyst on an Exhaust Slipstream. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), August 2013. http://dx.doi.org/10.55274/r0010800.
Анотація:
Oxidation catalysts are effective at reducing CO, formaldehyde, and VOCs as long as the catalyst temperature is above the light-off temperature for each species. It is important to understand the effects of temperature and space velocity on regulated species in order to effectively apply oxidation catalyst technology to lean burn engines, in particular 2-stroke engines that typically have lower exhaust temperatures. Various catalysts were tested on an exhaust slipstream coupled to a 4-stroke lean-burn engine which allows tests to be conducted at different temperatures and flow rates. The effect of the oxidation catalysts on NO2 and odor are also discussed.
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Defoort, Willson, and Olsen. L51849 Performance Evaluation of Exhaust Catalysts During the Initial Aging on Large Industrial Engines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 2001. http://dx.doi.org/10.55274/r0011213.
Анотація:
An investigation of catalyst performance during the initial aging process, providing insight into the deactivation rate of the catalyst and assisting in predicting the operational lifetime of the catalyst was preformed. The information gained through the test program provides a mechanism to assist in developing new technologies geared at reducing engine emission while providing improvements in efficiency, reliability, and operability for the aging industrial reciprocating engine fleet. Two natural gas lean burn engines, a 2-stroke, large bore slow speed and a 4-stroke medium bore medium speed, were operated at pre-determined conditions in conjunction with an oxidation catalyst. The aging process of the catalysts was observed. The research concluded that the catalyst performance is much lower than anticipated,particularly in relation to the aging process. During the aging process for the large bore 2-stroke engine (about 200 hours) the catalyst efficiency drops from 95% to 80% for CO and from 75% to 45% for CH2O. Results for the medium bore 4-stroke engine are better as a result of nearly 200°F higher catalyst temperatures. During aging (approximately 150 hours) the catalyst efficiencies are reduced from 99.2 to 97.7% for CO and from undetectable post catalyst levels (essentially 100% removal) to 67% for CH2O.
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Swanson, Dr Larry, and Christopher Samuelson. PR-362-06208-R01 Evaluation of Byproduct Emissions from Gas Turbine SCR Catalyst. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), February 2009. http://dx.doi.org/10.55274/r0010978.
Анотація:
The primary objective of the test program was to evaluate byproduct emissions at steady state and transient operating conditions for two commercially available SCR catalysts used in gas turbine applications. Both NOX removal efficiency and ammonia slip behavior were also examined to validate expected catalyst trends and activity. Even though the study replicated expected field catalyst process conditions as well as possible (e.g., flue gas temperatures, space velocities, and inlet species concentrations), the data and results are from pilot-scale testing only, and consequently may differ from actual gas turbine field tests.
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Bauza, Rodrigo, and Daniel Olsen. PR-179-20200-R01 Improved Catalyst Regeneration Process to Increase Poison Removal. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 2021. http://dx.doi.org/10.55274/r0012106.
Анотація:
In this work, the details of catalyst poison deposition are studied, and new catalyst restoration methods are explored. Lubrication oil makes its way through the combustion chamber and into the exhaust system, depositing poisons onto the catalyst and degrading catalyst performance. To estimate the degradation rate of the units and to find the best restoration method, two identical alumina-platinum oxidation catalysts were used in a dual setting, combining a field degradation engine and a laboratory testing engine. In order to find the best restoration process, the combination of both baking and washing is tested with poison deposition and performance analysis, and a hydrogen reduction is tested for the restoration of the platinum crystallites. The units were aged, then restored with the industry-standard washing procedure, then aged again until reaching non-compliance with emissions standards, and then restored a second time with a modified version of the industry-standard washing process that combines baking and washing. There is a related webinar.
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Jones and Hagedorn. PR-266-13206-R01 Role of Fuel Borne Metallic Catalysts in the Inhibition of NOx Formation. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2014. http://dx.doi.org/10.55274/r0010994.
Анотація:
Fuel borne catalysts (FBC) are additives that are mixed with the fuel prior to it passing into the combustion chamber. Metallic FBC are claimed to substantially reduce NOx in lean burn engines and otherwise improve performance characteristics. The purpose of this project is to research current literature on FBC and evaluate these catalyst materials and their economics to ultimately develop a plan that will lead to laboratory measurements on a full-scale, natural gas fired engine and, potentially, field tests. The first phase of the project, reported herein, consists of four parts: a review of current literature on FBC as a reduction agent of NOx, a survey of current FBC users, an economic analysis of FBC usage, and a summary and conclusion of the information obtained.
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Baumgardner, Davis, and Olsen. PR-179-13205-R01 Field Evaluation of Oxidation Catalyst Degradation - 2-Stroke Lean-Burn NG Engine. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), October 2015. http://dx.doi.org/10.55274/r0010036.
Анотація:
This study examines the degradation of an exhaust oxidation catalyst on a Cooper-Bessemer GMVH 12C2 gas engine. Critical parameters were determined, such as light-off temperature and reduction efficiency at 450 and 600?F. The catalyst surface was analyzed to examine the location and rate of poison deposition. Catalyst life was examined based on NESHAP guidelines. Catalyst life is strongly dependent on catalyst temperature and space velocity. For similar industrial applications, if the engine unit particulars are known, site operators can use the information in this study to predict when the oxidation catalyst will need to be either replaced or regenerated (washed).
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Gewirth, Andrew A., Paul J. Kenis, Ralph G. Nuzzo, and Thomas B. Rauchfuss. Final Report: Cathode Catalysis in Hydrogen/Oxygen Fuel Cells: New Catalysts, Mechanism, and Characterization. Office of Scientific and Technical Information (OSTI), January 2016. http://dx.doi.org/10.2172/1234970.