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Synthesis And Characterization Of Nickel Platinum And Cobalt Platinum Pseudomorphic Overlayer Catalysts Intended For Aqueous Phase Reforming Of Lactose
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Book Synopsis Synthesis and Characterization of Nickel Platinum and Cobalt Platinum Pseudomorphic Overlayer Catalysts Intended for Aqueous Phase Reforming of Lactose by : Michael D. Skoglund
Download or read book Synthesis and Characterization of Nickel Platinum and Cobalt Platinum Pseudomorphic Overlayer Catalysts Intended for Aqueous Phase Reforming of Lactose written by Michael D. Skoglund and published by . This book was released on 2013 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alumina supported bimetallic overlayer Re@Pd, Ni@Pt, and Co@Pt (core@shell) catalysts have been synthesized using the directed deposition technique. Single crystal and first principles computational studies have indicated that the formation of an overlayer atop a base metal can have an electronic effect on the surface overlaying metal that ultimately can increase or decrease binding energies for adsorbed species such as H2 and CO. In order to detect electronic modifications of the overlaying Pd or Pt metal several characterization techniques were employed. These techniques include: hydrogen and carbon monoxide chemisorption, an ethylene hydrogenation descriptor reaction, and X-ray absorption spectroscopy. Non-structured bimetallic alloy catalysts were also examined for the Ni and Co systems and when compared to overlayer catalysts exhibited notably different behavior. To determine if changes in catalytic behavior previously reported for Re@Pd overlayer catalyst was not caused by particle size effects, samples were made with different metal loading, dispersion, and particle size. Particle size effects have long been known to play a role in catalytic behavior as smaller particles tend to have more unsaturated, highly reactive, metal sites (e.g., corners, kinks, and edges). It was found that the 7 wt% Re@Pd (~6 nm particle size) demonstrated similar reductions in quality and strength of hydrogen adsorption as were seen for the smaller particle 2 wt% Re@Pd (~3 nm particle size) counterpart. Ethylene hydrogenation activity also proved consistent when normalized based on active Pd sites. Results indicate that the formation of a Pd overlayer was the reason for observed changes in adsorption and hydrogenation activity and the effect cannot be merely attributed to particle size effects. Aqueous phase reforming (APR) has proven capable of reforming a feed into H2 under moderate pressures and temperatures. Because the APR reaction produces H2 and CO products, a catalyst that has a decrease in product adsorptions strength should make for an ideal APR catalyst. Ni@Pt and Co@Pt catalyst have demonstrated a decrease in hydrogen and carbon monoxide adsorption strength and have shown a reduction in ethylene hydrogenation activity when compared to a pure Pt catalyst. XAS studies have shown that overlayer catalysts demonstrate near edge absorption characteristics dissimilar to that of bimetallic catalyst of similar loading indicating that overlayer synthesis is not merely creating a bimetallic alloy. Successive overlayer depositions resulted in an increase in both Pt-M coordination number and interatomic distance indicating that multiple depositions could be depositing multiple overlayers of platinum. However, even with multiple layers deposited, overlayer catalytic activity remains different than that of non-structured bimetallic alloys and is in line with single crystal and computational predictions for overlayer catalyst systems.
Book Synopsis Synthesis and Characterization of Pt and Pd Overlayer Catalysts for Aqueous Phase Reforming of Lactose and Hydrodeoygenation of Guaiacol and Anisole by : Qinghua Lai
Download or read book Synthesis and Characterization of Pt and Pd Overlayer Catalysts for Aqueous Phase Reforming of Lactose and Hydrodeoygenation of Guaiacol and Anisole written by Qinghua Lai and published by . This book was released on 2016 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supported bimetallic overlayer catalysts, Ni@Pt, Co@Pt, Ni@Pd, and Mo@Pt have been prepared by the directed deposition synthesis technique. The single crystal and computational studies have predicted that formation of Pd or Pt overlayer on Ni, Co or Mo base metal would cause a negative shift of d-band center of surface Pd or Pt, resulting in reduced binding strength for adsorbed species. The hydrogen chemisorption, ethylene hydrogenation descriptor reaction, XRD, H2-TPR, XAS and TEM studies were employed to characterize the catalysts. The alumina supported Ni@Pt and Co@Pt overlayer catalysts have been studied for aqueous phase reforming (APR) of lactose. Silica alumina supported Ni@Pt, Ni@Pd, and Mo@Pt catalysts have been investigated for hydrodeoxygenation (HDO) of lignin derived bio-oils. The H2 chemisorption and ethylene hydrogenation descriptor showed that alumina supported Ni@Pt and Co@Pt overlayer catalysts had reduced adsorption strength compared to a Pt only catalyst, which agrees with the computational prediction. XAS results showed that overlayer catalysts exhibited higher white line intensity than Pt catalyst, indicating a negative d-band shift for the Pt overlayer. Lactose APR studies showed that lactose could be used as feedstock to produce H2 and CO under desirable reaction condition. The Pt active sites of alumina supported Ni@Pt and Co@Pt overlayer catalysts showed significantly enhanced H2 production selectivity and activity when compared with that of a Pt only catalyst. The single deposition overlayer with the largest d-band shift showed the highest H2 activity. Silica alumina supported Ni@Pd, Ni@Pt, and Mo@Pt overlayer catalysts also showed the reduced adsorption strength compared to the Pd or Pt only catalyst. The TEM images of Ni@Pd overlayer catalyst provided evidence for a core/shell type structure. The H2-TPR results demonstrated the close interaction between Pt and Mo species for Mo@Pt overlayer catalysts. Guaiacol and anisole hydrodeoxygenation results showed that Pd and Pt active sites of overlayer catalysts showed significantly enhanced deoxygenation activity compared with that of Pd or Pt only catalyst. Further studies showed that guaiacol and anisole could be completely deoxygenated over the silica alumina supported metal catalysts at high W/F, yielding benzene, toluene, and xylenes as major products.
Book Synopsis Platinum Monolayer Electrocatalysts by : Radoslav Adzic
Download or read book Platinum Monolayer Electrocatalysts written by Radoslav Adzic and published by Springer Nature. This book was released on 2020-08-11 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes a science and technology of a new type of electrocatalysts consisting of a single atomic layer of platinum on suitable supports. This development helped overcome three major obstacles—catalysts‘ cost, activity, and stability—for a broad range of fuel cell applications. The volume begins with a short introduction to the science of electrocatalysis, covering four reactions important for energy conversion in fuel cells. A description follows of the properties of metal monolayers on electrode surfaces, and underpotential deposition of metals. The authors then describe the concept of Pt monolayer electrocatalysts and its implications and their synthesis by galvanic displacement of less-noble metal monolayers and other methods. The main part of the book presents a discussion of catalysts’ characterization and catalytic properties of Pt monolayers for the four main reactions of electrochemical energy conversion: oxygen reduction and oxidation of hydrogen, methanol and ethanol. The book concludes with a treatment of scale-up syntheses, fuel cell tests, catalysts’ stability and application prospects.
Book Synopsis Controlled Synthesis of Pt-Ni Bimetallic Catalysts and Study of Their Catalytic Properties by : Yuen Wu
Download or read book Controlled Synthesis of Pt-Ni Bimetallic Catalysts and Study of Their Catalytic Properties written by Yuen Wu and published by Springer. This book was released on 2016-05-14 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the controlled synthesis of Pt–Ni bimetallic nanoparticles and the study of their catalytic properties. It discusses in detail the nucleation mechanism and the growth process of bimetallic systems, which is vital for a deeper understanding of the design of bimetallic catalysts. The author presents four pioneering studies: (1) syntheses of water-soluble octahedral, truncated octahedral, and cubic Pt–Ni nanocrystals and the study of their structure-activity relationship in model hydrogenation reactions; (2) a strategy for designing a concave Pt–Ni alloy using controllable chemical etching; (3) defect-dominated shape recovery of nanocrystals, which is a new synthesis strategy for trimetallic catalysts; (4) a sophisticated construction of Au islands on Pt−Ni, which is an ideal trimetallic nanoframe catalyst. This thesis inspires researchers working in materials, catalysis as well as other interdisciplinary areas.
Book Synopsis Synthesis and Characterization of Platinum Based Catalysts for Fuel Cells by : Sonam Patel
Download or read book Synthesis and Characterization of Platinum Based Catalysts for Fuel Cells written by Sonam Patel and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Platinum (Pt) and platinum alloys have attracted wide attention as catalysts to attain high performance to increase the power density and reduce the component cost of polymer electrolyte membrane fuel cells (PEMFCs). Extensive research has been conducted in the areas of new alloy development and understanding of mechanisms of electrochemical oxygen reduction reaction (ORR). The durability of PEMFCs is also a major barrier to the commercialization of these fuel cells. Recent studies have suggested that potential cycling can gradually lead to loss of active surface area due to Pt dissolution and nanoparticle grain growth [1]. In this thesis we report a one-step synthesis of highly-dispersed Pt nanoparticles and Pt- Cobalt supported on Ketjen carbon black (20% Pt/C & 20% Pt3Co/C) as electro-catalysts for PEMFCs. Pt particles with size in the range of ~ 2.6nm (Pt/C) and 3.9 nm (Pt3Co/C) were obtained through adsorption on carbon supports and subsequently thermal decomposition of platinum acetylacetonate (Pt(acac)2). A comparative characterization analysis, including X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM), FT-iR, EDAX, cyclic voltammetry (CV), and oxygen reduction reaction (ORR) activity, was performed on the synthesized and commercial (46.5wt% TKK) catalysts. The analysis was to reveal the Pt dispersion on the carbon support, particle size and distribution, electrochemical surface area (ECA), and ORR activities of these catalysts. It was found that the synthesized Pt/C showed similar particle size to that of the TKK catalysts (2.6nm and 2.7nm, respectively), but narrower particle size distribution; while the particle size for Pt3Co/C was found to be ~3.9 nm. Accelerated durability tests (ADT) under potential cycles were also performed for Pt/C and TKK to study the electrochemical degradation of the catalysts in corrosive environments. The ADTs revealed that the two catalysts (Pt/C & TKK) were comparable with respect to degradation in ECA and ORR activities. Initial electrochemical evaluation of Pt3Co/C was conducted, but durability studies were not attempted in this thesis due to its worse ORR kinetics than those of the Pt/C catalyst. From the experimental data, it was found that particle size impacted negatively the ECA and ORR activity of the catalysts.
Book Synopsis Synthesis and Characterization of Platinum-based Multi-component Catalysts for Direct Methanol Fuel Cells by : Li Ren
Download or read book Synthesis and Characterization of Platinum-based Multi-component Catalysts for Direct Methanol Fuel Cells written by Li Ren and published by . This book was released on 2007 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In the thesis work, Pt-based binary, ternary, quaternary alloy anode catalysts supported on sonochemically treated multi-walled carbon nanotubes (CNTs) were synthesized with ethylene glycol reduction of corresponding metal chloride salts. Inductively coupled plasma-mass spectroscopy (ICP-MS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) were used for catalyst characterization. Cyclic voltammetry for methanol oxidation and CO stripping were used to evaluate the performance of the catalysts. PtRu nanoparticles supported on CNTs (PtRu/CNT) were prepared under a series of pHs. It was found that the PtRu particle size, composition, and catalytic activity were all sensitive to the deposition pHs. CO stripping results provided the peak potential and active surface area for each catalyst. The atomic ratios tended to approach the predetermined ratio 1:1 with the increase of pH, which is favored by bi-functional catalytic mechanism. PtRu catalysts prepared at higher pHs presented better electrochemical activity toward methanol oxidation. Humidified oxygen treatment of the PtRu/CNT led to improved activity of the catalysts toward methanol electro-oxidation, implying that Ru hydroxide is better than Ru as a co-catalyst. PtRu, PtOs, PtRuOs, and PtRuOsIr nanoparticles supported on CNTs with atomic ratios of Pt:Ru (tr:46), Pt:Os (80:20), Pt:Ru:Os (54:36:10), and Pt:Ru:Os:Ir (44:36:10:5) were prepared. Cyclic voltammetry for the methanol oxidation and CO stripping at the catalysts showed that PtRu/CNT and PtRuOsIr/CNT have the best performance toward methanol oxidation, PtRuOs/CNT has the lowest activity, but PtOs/CNT exhibits better catalytic activity only at potential or 0.73 V"--Abstract, leaf iii.
Book Synopsis Synthesis and Characterization of Supported Rhenium, Iridium, and Platinum Catalysts by : Scott K. Purnell
Download or read book Synthesis and Characterization of Supported Rhenium, Iridium, and Platinum Catalysts written by Scott K. Purnell and published by . This book was released on 1994 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis and Characterization of Platinum Group Metal Free Catalysts for the Electro Catalytic Oxygen Reduction Reaction by : Fang Luo
Download or read book Synthesis and Characterization of Platinum Group Metal Free Catalysts for the Electro Catalytic Oxygen Reduction Reaction written by Fang Luo and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis, Characterization, and Preparation of Platinum-ruthenium Catalysts by : Hong Yian Lin
Download or read book Synthesis, Characterization, and Preparation of Platinum-ruthenium Catalysts written by Hong Yian Lin and published by . This book was released on 1998 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis and Characterization of Bimetallic Platinum-gold Catalysts by : Corina Mihut
Download or read book Synthesis and Characterization of Bimetallic Platinum-gold Catalysts written by Corina Mihut and published by . This book was released on 2002 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis and Characterization of Binary and Ternary Platinum Alloy Catalysts for Direct Methanol Fuel Cell Application by :
Download or read book Synthesis and Characterization of Binary and Ternary Platinum Alloy Catalysts for Direct Methanol Fuel Cell Application written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis and Characterization of Platinum-Based Fuel Cell Catalysts by :
Download or read book Synthesis and Characterization of Platinum-Based Fuel Cell Catalysts written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Addition of Platinum to Palladium-cobalt Nanoalloy Catalyst by Direct Alloying and Galvanic Displacement by : Brent Wise
Download or read book Addition of Platinum to Palladium-cobalt Nanoalloy Catalyst by Direct Alloying and Galvanic Displacement written by Brent Wise and published by . This book was released on 2010 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct methanol fuel cells (DMFC) are being investigated as a portable energy conversion device for military and commercial applications. DMFCs offer the potential to efficiently extract electricity from a dense liquid fuel. However, improvements in materials properties and lowering the cost of the electrocatalysts used in a DMFC are necessary for commercialization of the technology. The cathode electrocatalyst is a critical issue in DMFC because the state-of-the-art catalyst, platinum, is very expensive and rare, and its performance is diminished by methanol that crosses over from the anode to the cathode through the Nafion membrane. This thesis investigates the addition of platinum to a palladium-cobalt nanoalloy electrocatalyst supported on carbon black in order to improve catalyst activity for the oxygen reduction reaction (ORR) and catalyst stability against dissolution in acidic environment without significantly reducing the methanol-tolerance of the catalyst. Platinum was added to the palladium-cobalt nanoalloy catalyst using two synthesis methods. In the first method, platinum was directly alloyed with palladium and cobalt using a polyol reduction method, followed by heat treatment in a reducing atmosphere to form catalysts with 11 and 22 atom % platinum. In the second method, platinum was added to a palladium-cobalt alloy by galvanic displacement reaction to form catalysts with 10 and 22 atom % platinum. The palladium cobalt alloy was synthesized using a polyol method, followed by heat treatment in a reducing atmosphere to alloy the nanoparticles before the Pt displacement. It was found that both methods significantly improve catalyst activity and stability, with the displaced catalysts showing a higher activity than the corresponding alloy catalyst. However the alloy catalysts showed similar resistance to dissolution as the displaced catalysts, and the alloyed catalysts were more tolerant to methanol. The displaced catalyst with 22 atom % platinum (8 wt. % Pt overall) performed similar to a 20 wt. % commercial platinum catalyst in both RDE and single cell DMFC tests. The 10 and 22 atom % Pt displaced catalysts and 22 atom % Pt alloyed all showed higher Pt mass specific activities than a commercial Pt catalyst.
Book Synopsis Application of Transition Metal Catalysts in Organic Synthesis by : L. Brandsma
Download or read book Application of Transition Metal Catalysts in Organic Synthesis written by L. Brandsma and published by Springer. This book was released on 1998 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous catalysis is an important strategy for the synthesis of high-valued chemicals. L. Brandsma has carefully selected and checked the experimental procedures illustrating the catalytic use of copper, nickel, and palladium compounds in organic synthesis. All procedures are on a preparative scale, make economic use of solvents and catalysts, avoid toxic substances and have high yields.
Book Synopsis Overlayer Catalysts for Efficient Biomass Conversion by : Chen Zhang
Download or read book Overlayer Catalysts for Efficient Biomass Conversion written by Chen Zhang and published by . This book was released on 2016 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extensive research efforts have been focusing on developing new energy resources, with biomass being the only renewable source of carbon that can be used to make liquid fuels and chemicals. Platinum-based catalysts have shown excellent reactivity and stability for various biomass conversion reactions. However, previous studies have suggested that the strong adsorption of H2 or CO products would block the platinum surface active site and reduce the catalyst reactivity. Bimetallic overlayer catalysts with a pseudomorphic metal overlayer atop a different bulk metal suggest an effective approach to tackle this problem. A Pt overlayer on top of Ni or Co has been demonstrated computationally and experimentally to display a reduced d-band center energy and thus weakened adsorption strength for H2 and CO. Accordingly, overlayer catalysts with reduced binding strength of H2 and CO are expected to show increased reactivity in reactions where strong H2 or CO binding are shown to inhibit the reactivity. In this research, several overlayer catalysts have been synthesized by the directed deposition technique. Heats of H2 adsorption of overlayer catalysts calculated from H2 chemisorption were decreased compared to pure Pt. The ethylene hydrogenation descriptor reaction also showed decreased turnover frequencies for overlayer catalysts compared to pure Pt, suggesting weaker hydrogen adsorption strength of over layer catalysts than pure Pt. This reduced adsorption strength is consistent with previous computational predictions. Overlayer catalysts were tested in aqueous phase glycerol hydrodeoxygenation and furfural hydrogenation. In glycerol hydrodeoxygenation, overlayer catalysts showed enhanced turnover frequencies in glycerol conversion and hydrocarbon production rates. This enhancement is in agreement with the expectation that reduced adsorption strength of Pt overlayer would increase Pt reactivity. Also, with Ir@Pt (core@shell) overlayer catalysts, higher selectivity toward C-O bond cleavage than C-C bond cleavage was achieved, suggesting promising application in producing fully-deoxygenated products without breaking C-C bonds. In furfural hydrogenation, overlayer catalysts showed much higher turnover frequencies in furfural conversion than their monometallic counterparts.
Book Synopsis The Synthesis and Characterization of New Platinum, Gold and Silver Complexes, and Their Application as Hydrosilylation Catalysts by : Bradley M. Wile
Download or read book The Synthesis and Characterization of New Platinum, Gold and Silver Complexes, and Their Application as Hydrosilylation Catalysts written by Bradley M. Wile and published by . This book was released on 2007 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Late transition metal complexes are traditionally employed as catalysts for a variety of organic transformations. The hydrosilylation reaction represents the formal addition of a Si-H bond to an unsaturated organic substrate, and is one such transformation that has received much attention in the scientific literature. The recent development of a series of P,N- and P-substituted indene ligands by the Stradiotto group prompted a study of group 10 and 11 complexes derived from these complexes. Synthesis and structural characterization of Pd(II), Pt(II), Au(III) and Au(I) species is reported, followed by stability and reactivity studies for these complexes. Selected complexes, as well as several M(I)/phosphine (M = Ag, Au) mixtures were evaluated as catalysts for the hydrosilylation reaction. Comparison of a neutral Pt(II) complex and a closely related neutral, charge-separated Au(III) zwitterion reveals significant differences in stability and reactivity, as well as in catalytic competence for the hydrosilylation of alkenes. Key Pt(II) complexes also display interesting reactivity that points to the potential for related species to accomplish intermolecular C-H bond activation. The Ag(I) and Au(I) catalyst systems described represent the first examples of Ag-mediated and room temperature Au-mediated hydrosilylation reactions, and as such, represent a significant contribution to scientific development. Future directions and proposed modifications to substituted indene ligands are discussed.
Book Synopsis Platinum-tin Bimetallic Catalysts Supported on L-zZeolite by : Hui Wang
Download or read book Platinum-tin Bimetallic Catalysts Supported on L-zZeolite written by Hui Wang and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
