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This text explores the optimization of catalytic materials through traditional and novel methods of catalyst preparation, characterization, and monitoring for oxides, supported metals, zeolites, and heteropolyacids. It focuses on the synthesis of bulk materials and of heterogeneous materials, particularly at the nanoscale. The final chapters examine pretreatment, drying, finishing effects, and future applications involving catalyst preparation and the technological advances necessary for continued progress. Topics also include heat and mass transfer limitations, computation methods for predicting properties, and catalyst monitoring on laboratory and industrial scales.
Precise control of metal nanoparticles' size, composition, and dispersity over high surface area supports are highly desirable to address current challenges in energy storage and conversion as well as catalytic processes involving precious metals. Therefore, developing viable synthetic routes that enable new catalytic systems derived from inexpensive transition metals or limited use of precious metals is vital for clean energy applications such as fuel cells and rechargeable batteries or affordable drugs in the pharmaceuticals arena. In addition to metal components of heterogeneous catalysts, the catalyst support is an integral part of catalyst design as it can impart both physical stability and catalytic enhancement through strong metal-support interactions. In particular, recent studies have shown that the incorporation of heteroatoms like nitrogen and phosphorus in high surface area carbon supports is an effective approach for tailoring the textural and electronic properties of carbon supports. Here we introduce different supported metal nanoparticles on high surface area supports, with their characteristic tuned toward different applications. In the first project, we developed an iron phosphide doped porous carbon system (PFeC) and used it as a cathode catalyst for oxygen reduction reaction (ORR) in fuel cells. The conversion of chemical energy to electrical energy is a sustainable approach for energy production achieved by fuel cells. Currently, the noble metal platinum, in the form of 20 wt% Pd deposited on carbon support (Pt/C) is the commercially available catalyst for the ORR. Sluggish ORR mechanism and lack of long-term stability demand for a more sustainable, inexpensive, and kinetically efficient replacement catalyst. Here iron phosphide nanoparticles (NPs) incorporated in a phosphorus-doped porous carbon, with a high specific area (SABET = 967 m2 g−1) was synthesized using inexpensive reactants, triphenylphosphine and iron chloride by a facile carbonization/chemical activation method via zinc chloride. PFeC selectively reduces O2 via an efficient reaction pathway and exhibits superior long-term stability than Pt/C. The superior electrocatalytic performance is credited to the synergistic effects between the P and Fe which, form well-defined and well-distributed nanoparticles confined in highly porous carbon nanosheets. In the second project, supported palladium-based ultra-small bimetallic NPs deposited on mesoporous fumed silica support (SABET = 350 m2 g−1) were synthesized and used as a catalyst for Suzuki -Miyaura cross-coupling (SCC) reactions. Bimetallic NPs consisting of active metal Pd and base metals (Cu, Ni, and Co) were deposited on the silica support through strong electrostatic (SEA) synthesis method yielding homogeneously alloyed nanoparticles with an average size of 1.3 nm. All bimetallic catalysts were found to be highly active toward SCC surpassing the activity of monometallic Pd/SiO2. In particular, the catalyst consisting of Cu and Pd (CuPd/SiO2), performed the SCC with a remarkable turn over frequency of 248000. The combination of Pd with base metals helps in retaining the Pd0 status by charge donation from base metals to Pd and thus facilitating the SCC, in specific lowering the activation energy of the aryl halide oxidative addition rate-limiting step. In the third and last project, functionalized supports are widely utilized in energy conversion and energy storage applications. High surface area porous carbon materials have been introduced as a highly active cathode material for Lithium-sulfur batteries (LSB). The electrochemical performance of the LSB can be largely improved by the efficient reversible conversion of lithium polysulfides to Li2S during discharge and to elemental sulfur during charge. Nickel NPs deposited on high surface area nitrogen-doped carbon support (Ni/BIDC-900, SABET = 3560 m2 g−1) act as active centers for the adsorption of polysulfides during the discharge process and rapidly convert them to Li2S while catalyzing Li2S oxidation to sulfur in the reverse process. The addition of Ni NPs improves the reaction kinetics and activity retention of the LSB.
Illustrating developments in electrochemical nanotechnology, heterogeneous catalysis, surface science and theoretical modelling, this reference describes the manipulation, characterization, control, and application of nanoparticles for enhanced catalytic activity and selectivity. It also offers experimental and synthetic strategies in nanoscale surface science. This standard-setting work clariefies several practical methods used to control the size, shape, crystal structure, and composition of nanoparticles; simulate metal-support interactions; predict nanoparticle behavior; enhance catalytic rates in gas phases; and examine catalytic functions on wet and dry surfaces.
Using new instrumentation and experimental techniques that allow scientists to observe chemical reactions and molecular properties at the nanoscale, the authors of Surface and Nanomolecular Catalysis reveal new insights into the surface chemistry of catalysts and the reaction mechanisms that actually occur at a molecular level during catalys
The need to improve both the efficiency and environmental acceptability of industrial processes is driving the development of heterogeneous catalysts across the chemical industry, including commodity, specialty and fine chemicals and in pharmaceuticals and agrochemicals. Drawing on international research, Supported Catalysts and their Applications discusses aspects of the design, synthesis and application of solid supported reagents and catalysts, including supported reagents for multi-step organic synthesis; selectivity in oxidation catalysis; mesoporous molecular sieve catalysts; and the use of Zeolite Beta in organic reactions. In addition, the two discrete areas of heterogeneous catalysis (inorganic oxide materials and polymer-based catalysts) that were developing in parallel are now shown to be converging, which will be of great benefit to the whole field. Providing a snapshot of the state-of-the-art in this fast-moving field, this book will be welcomed by industrialists and researchers, particularly in the agrochemicals and pharmaceuticals industries.
Catalysis is one of the pillars of the chemical industry. While the use of catalyst is typically recognized in the automobile industry, their impact is more widespread as; catalysts are used in the synthesis of 80% of the US commercial chemicals. Despite the improved selectivity provided by catalyst, process inefficiencies still threaten the sustainability of a number of synthesis methods, especially in the pharmaceutical industry. Recyclable solid supported catalysts offer a unique opportunity to address these inefficiencies. Such systems coupled with continuous synthesis techniques, have the potential to significantly reduce the waste to desired product ratio (E-factor) of the production techniques. This research focuses developing sustainable processes to synthesize organic molecules by using continuous synthesis methods. In doing so, solid supported metal catalyst systems were identified, developed, and implemented to assist in the formation of carbon-carbon bonds. Newly developed systems, which utilized metal nanoparticles, showed reactivity and recyclability, comparable to commercially available catalyst. Nanoparticles are emerging as useful materials in a wide variety of applications including catalysis. These applications include pharmaceutical processes by which complex and useful organic molecules can be prepared. As such, an effective and scalable synthesis method is required for the preparation of nanoparticle catalysts with significant control of the particle size, uniform dispersion, and even distribution of nanoparticles when deposited on the surface of a solid support. This project describes the production of palladium nanoparticles on a variety of solid supports and the evaluation of these nanoparticles for cross coupling reactions. This report highlights novel synthesis techniques used in the formation of palladium nanoparticles using traditional batch reactions. The procedures developed for the batch formation of palladium nanoparticles on different solid supports, such as graphene and carbon nanotubes, are initially described. The major drawbacks of these methods are discussed, including limited scalability, variation of nanoparticle characteristics from batch to batch, and technical challenges associated with efficient heating of samples. Furthermore, the necessary conditions and critical parameters to convert the batch synthesis of solid supported palladium nanoparticles to a continuous flow process are presented. This strategy not only alleviates the challenges associated with the robust preparation of the material and the limitations of scalability, but also showcases a new continuous reactor capable of efficient and direct heating of the reaction mixture under microwave irradiation. This strategy was further used in the synthesis of zinc oxide nanoparticles. Particles synthesized using this strategy as well as traditional synthesis methods, were evaluated in the context industrially relevant applications.
This handbook and ready reference brings together all significant issues of practical importance in selected topics discussing recent significant achievements for interested readers in one single volume. While covering homogeneous and heterogeneous catalysis, the text is unique in focusing on such important aspects as using different reaction media, microwave techniques or catalyst recycling. It also provides a comprehensive treatment of key issues of modern-day coupling reactions having emerged and matured in recent years and emphasizes those topics that show potential for future development, such as continuous flow systems, water as a reaction medium, and catalyst immobilization, among others. With its inclusion of large-scale applications in the pharmaceutical industry, this will equally be of great interest to industrial chemists. From the contents * Palladium-Catalyzed Cross-Coupling Reactions - A General Introduction * High-turnover Heterogeneous Palladium Catalysts in Coupling Reactions: the Case of Pd Loaded on Dealuminated Y Zeolites Palladium-Catalyzed Coupling Reactions with Magnetically Separable Nanocatalysts * The Use of Ordered Porous Solids as Support Materials in Palladium-Catalyzed Cross-Coupling Reactions * Coupling Reactions Induced by Polymer-Supported Catalysts * Coupling Reactions in Ionic Liquids * Cross-Coupling Reactions in Aqueous Media * Microwave-Assisted Synthesis in C-C and C-Heteroatom Coupling Reactions * Catalyst Recycling in Palladium-Catalyzed Carbon-Carbon Coupling Reactions * Nature of the True Catalytic Species in Carbon-Carbon Coupling Reactions with * Heterogeneous Palladium Precatalysts * Coupling Reactions in Continuous Flow Systems * Large-Scale Applications of Palladium-Catalyzed Couplings in the Pharmaceutical Industry