Synthesis of silicon nanoparticles in a pilot-plant-scale microwave plasma reactor: Impact of flow rates and precursor concentration on the nanoparticle size and aggregation
“…On the basis of the flowrates mentioned in Table 1, a production rate of approximately 0.8–1 g coated silicon NPs per hour could be harvested from the filter. The production capacity of the reactor (at identical process conditions) can be increased by at least a factor of 20 by increasing the flow rate of monosilane; however, in this case, the formation of aggregated silicon NPs is observed, [ 20 ] which was not intended in this study.…”
This study investigates the feasibility of plasma-supported in-line functionalization of silicon nanoparticles (NPs) in an atmospheric pressure gas-phase reactor. The approach utilizes the synthesis of core silicon NPs and their subsequent coating downstream of the particle formation zone. In-line coating is accomplished with a cylindrical coating nozzle to achieve homogenous mixing of coating precursor vapors with in-coming NPs. Multiple siloxanes were tested for their coating suitability and their ability towards coating homogeneity. It was
“…On the basis of the flowrates mentioned in Table 1, a production rate of approximately 0.8–1 g coated silicon NPs per hour could be harvested from the filter. The production capacity of the reactor (at identical process conditions) can be increased by at least a factor of 20 by increasing the flow rate of monosilane; however, in this case, the formation of aggregated silicon NPs is observed, [ 20 ] which was not intended in this study.…”
This study investigates the feasibility of plasma-supported in-line functionalization of silicon nanoparticles (NPs) in an atmospheric pressure gas-phase reactor. The approach utilizes the synthesis of core silicon NPs and their subsequent coating downstream of the particle formation zone. In-line coating is accomplished with a cylindrical coating nozzle to achieve homogenous mixing of coating precursor vapors with in-coming NPs. Multiple siloxanes were tested for their coating suitability and their ability towards coating homogeneity. It was
“…6. Aerosols of elemental nanoparticles may be generated directly through gas-phase reactions [104], including via plasma-assisted synthesis [105][106][107], thermal initiation in hot wall reactors [108] or shock tubes [109], flame synthesis, photolysis via UV lasers [88,97], laser ablation [110], and arc discharge [40]. Plasma-assisted synthesis routes are particularly attractive, since they involve a well-defined reacting gas atmosphere and produce particles free of contaminants.…”
Laser-induced incandescence (LII) is a widely used combustion diagnostic for in situ measurements of soot primary particle sizes and volume fractions in flames, exhaust gases, and the atmosphere. Increasingly, however, it is applied to characterize engineered nanomaterials, driven by the increasing industrial relevance of these materials and the fundamental scientific insights that may be obtained from these measurements. This review describes the state of the art as well as open research challenges and new opportunities that arise from LII measurements on non-soot nanoparticles. An overview of the basic LII model, along with statistical techniques for inferring quantities-of-interest and associated uncertainties is provided, with a review of the application of LII to various classes of materials, including elemental particles, oxide and nitride materials, and non-soot carbonaceous materials, and core–shell particles. The paper concludes with a discussion of combined and complementary diagnostics, and an outlook of future research.
“…Detailed analyses of reactive media were also performed in further combustion-related systems that involve plasma-assisted processes and enhancement by electric and magnetic fields [380] , [381] , [382] , [383] , [384] , [385] , [386] , [387] , [388] , [389] , [390] , [391] , [392] . Nonthermal plasma-assisted processes offer means for reduction of pollutant emissions and extension of the combustion-operating regime [383 , 384] , including ultra-lean [384] and low-temperature combustion [384] , [385] , [386] (see also Section 2.2 ).…”
Section: Combustion Chemistry and Beyond – A Few Examplesmentioning
confidence: 99%
“… Plasma-assisted processes show attractive potential for reactive systems involving gas-phase reactions in and beyond combustion, such as in the production of nanoparticles from gas-phase precursors [391] and in the conversion of CO 2 and gaseous hydrocarbons, e.g., from flares, in an efficient single-step GTL process towards methanol [392] . A common aim for the understanding and optimization of such chemical processes is to establish fundamental knowledge of the reaction behavior, including that of charged particles, obtained from direct measurement of the relevant process parameters, and to use this information to develop appropriate, transferable models, needed for safety, efficiency, selectivity, and scaling purposes.…”
Section: Combustion Chemistry and Beyond – A Few Examplesmentioning
Combustion involves chemical reactions that are often highly exothermic. Combustion systems utilize the energy of chemical compounds released during this reactive process for transportation, to generate electric power, or to provide heat for various applications. Chemistry and combustion are interlinked in several ways. The outcome of a combustion process in terms of its energy and material balance, regarding the delivery of useful work as well as the generation of harmful emissions, depends sensitively on the molecular nature of the respective fuel. The design of efficient, low-emission combustion processes in compliance with air quality and climate goals suggests a closer inspection of the molecular properties and reactions of conventional, bio-derived, and synthetic fuels. Information about flammability, reaction intensity, and potentially hazardous combustion by-products is important also for safety considerations. Moreover, some of the compounds that serve as fuels can assume important roles in chemical energy storage and conversion. Combustion processes can furthermore be used to synthesize materials with attractive properties.
A systematic understanding of the combustion behavior thus demands chemical knowledge. Desirable information includes properties of the thermodynamic states before and after the combustion reactions and relevant details about the dynamic processes that occur during the reactive transformations from the fuel and oxidizer to the products under the given boundary conditions. Combustion systems can be described, tailored, and improved by taking chemical knowledge into account. Combining theory, experiment, model development, simulation, and a systematic analysis of uncertainties enables qualitative or even quantitative predictions for many combustion situations of practical relevance.
This article can highlight only a few of the numerous investigations on chemical processes for combustion and combustion-related science and applications, with a main focus on gas-phase reaction systems. It attempts to provide a snapshot of recent progress and a guide to exciting opportunities that drive such research beyond fossil combustion.
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