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Tailor-made Carbonaceous Nanoparticles by Multiscale Combustion Design

English title Tailor-made Carbonaceous Nanoparticles by Multiscale Combustion Design
Applicant Pratsinis Sotiris E.
Number 182668
Funding scheme Project funding (Div. I-III)
Research institution Institut für Verfahrenstechnik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Mechanical Engineering
Start/End 01.01.2019 - 31.12.2022
Approved amount 1'075'342.00
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All Disciplines (9)

Discipline
Mechanical Engineering
Particle Physics
Physical Chemistry
Climatology. Atmospherical Chemistry, Aeronomy
Fluid Dynamics
Organic Chemistry
Material Sciences
Chemical Engineering
Other disciplines of Engineering Sciences

Keywords (8)

Flame Aerosol Reactors; Global Warming; Nucleation; Gas Phase Chemistry; Particulate Emissions; Multi Scale Modeling; Carbonaceous Nanoparticles; Radiative Forcing

Lay Summary (German)

Lead
Kohlenstoffhaltige Nanopartikel sind allgegenwärtig und ziehen in verschiedensten
Lay summary
Wissenschaftsbereichen grosse Aufmerksamkeit auf sich. Zum Beispiel ist Carbon Black, das nach Volumen und Umsatz grösste flammgefertigte Nanomaterial (eine Multimilliarden-Dollar-Industrie), ein Hauptbestandteil in Reifen, Tinten, Batterien und Solarzellen, während hochwertige Kohlenstoff beschichte Cobalt-Nanopartikel (200 $ / g) als magnetische Biofluide in der Pharmazie verwendet werden. Andererseits ist Russ - ein Material, das Carbon Black sehr ähnlich ist - ein Luftschadstoff. Die optische Charakterisierung von Russ durch Lichtabsorption und -streuung ist wichtig, um den Einflusses von Russ auf das Klima einschätzen zu können, sowie für die optische Diagnostik in der Prozesskontrolle und Branddetektion. Flammengefertigte, kohlenstoffhaltige Nanopartikel weisen fraktal-artige Strukturen auf, die aus mehreren kompakten Primärpartikeln bestehen. Dies wird derzeit vernachlässigt und ihre optischen Eigenschaften werden unter der Annahme geschätzt, dass solche Strukturen einzelne Kugeln sind! Diese Vereinfachung verhindert eine genaue Schätzung der Umweltauswirkungen von Ruß durch Strahlung, sowie die Charakterisierung durch optische Diagnosegeräte und die selektive Erkennung durch Feuersensoren, die allein in Großbritannien jährlich etwa 1 Mrd. £ an Kosten verursachen. Die vorgeschlagene Forschung zielt darauf ab, ein Multi-Scale-Design-Tool zu entwickeln, um realistische Partikelmorphologie und -zusammensetzung vorherzusagen und zu verstehen, wie optische Eigenschaften mit den Partikeleigenschaften und den Synthesebedingungen zusammenhängen. Diese Forschung wird die Berechnung der optischen Eigenschaften von kohlenstoffhaltigen Nanopartikeln auf eine solide wissenschaftliche Grundlage stellen. Auf diese Weise wird ein glaubwürdiges Schema entwickelt, um ihre optischen Eigenschaften von ihren gemessenen Eigenschaften zu erhalten.
Direct link to Lay Summary Last update: 04.10.2018

Lay Summary (English)

Lead
Taylor-made Carbonaceous Nanoparticles by Multiscale Combustion Design
Lay summary

Carbonaceous nanoparticles are ubiquitous attracting attention in across various fields of science. For example, carbon black, the largest flame-made nanomaterial by value and volume (a multi-billion dollar industry), is a major component in tires, inks, batteries and solar cells, while high value ($200/g) carbon-coated cobalt nanoparticles are used as magnetic biofluids for drug delivery. On the other hand, soot - a material very similar to carbon black - is an air pollutant. Soot optical characterization by light absorption and scattering is essential for estimation of the impact of soot on climate, as well as for optical diagnostics in process control and fire detection. Flame made carbonaceous nanoparticles have fractal-like structures made of several compact primary particles. Yet their optical properties are estimated assuming that such structures are single spheres! This oversimplification impedes accurate estimation of the environmental impact of soot as quantified by the radiative forcing, as well as for characterization by optical diagnostics and for selective detection with fire sensors that is responsible for false alarms costing £1B/y in UK alone. The proposed research aims to develop a multi-scale computational design tool to predict realistic particle morphology and composition in order to understand how particle optical properties are connected with particle characteristics and synthesis conditions. This research will place the calculation of the optical properties of carbonaceous nanoparticles on a firm scientific basis. That way a credible scheme for obtaining their optical properties from their measured characteristics will be developed.

Direct link to Lay Summary Last update: 04.10.2018

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
149144 Multiscale Design of Aerosol Synthesis of Nanomaterials 01.10.2013 Project funding (Div. I-III)

Abstract

Carbonaceous nanoparticles are ubiquitous attracting attention in various fields of science. Formation of carbonaceous aerosols by combustion is critical in synthesis of functional nanomaterials but also has high impact on human health and environment. For example, carbon black, the largest flame-made nanomaterial by value and volume (a $10B industry), is a major component in tires, inks, batteries and solar cells, while high value ($1’000/g) carbon-coated cobalt nanoparticles are used as magnetic biofluids. On the other hand, soot - a material very similar to carbon black - is an air pollutant. Nascent and mature soot particles with diameter between 1-50 and 50-1000 nm, respectively, are formed during transportation, manufacturing, power generation and fires. Soot optical characterization by light absorption and scattering is essential for estimation of its impact on climate, as well as for optical diagnostics, including fire detectors. Our understanding of carbonaceous nanoparticle formation in flames has advanced from an empirical description to an age of quantitative modeling for, at least, some nanoparticle properties. At the same time, however, rather little is known about critical particle formation steps like nucleation, surface growth and oxidation. This lack of understanding hinders the design of combustion and after-treatment processes for minimal, if not zero, emissions of soot, as well as the systematic scale-up and exploration of the properties of flame-made nanomaterials. Also at a time when society is alarmed about climate change, still soot optical properties are calculated by Mie theory for spheres neglecting the fractal-like morphology of soot! This impedes accurate estimation of the environmental impact of soot as quantified by the radiative forcing, as well as characterization by optical diagnostics and for selective detection with fire sensors that is responsible for false alarms costing £1B/y in UK alone.Recent advances in aerosol and combustion sciences reveal that nucleation, coagulation, and surface growth control product particle size, composition and morphology. The dynamics of these processes span 10-15 orders of magnitude in length and time requiring model integration at different length/time scales for systematic process understanding. These models can be distinguished into continuum, mesoscale and atomistic ones that are interconnected for multiscale process design. That way critical product properties and process variables can be estimated from first principles. For example, carbon nanoparticle formation in flames relies on the nucleation of large aromatic molecules. The relative strength of nucleation compared to surface growth and coagulation controls particle size and fractal morphology, respectively. Classical nucleation theory cannot explain particle formation at high temperature because it does not consider chemical bonding between molecules (carbonization) that is crucial for cluster stability. Such a process can be followed quantitatively with a mechanism accounting for reactive dimerization of aromatic molecules. Similarly, current soot oxidation rates rely on simplistic assumptions of particle morphology. Scaling laws considering the fractal-like soot structure from mesoscale simulations can facilitate the in-situ measurement of soot oxidation. The calculated nucleation rates and reliably measured soot oxidation rates can then be used to interface mesoscale simulations of the evolving fractal morphology of particles with continuum simulations of the flame fluid mechanics and gas phase chemistry, enabling us to explore the effects of high temperature particle residence time and fuel chemistry on product particle properties. Thus, a key focus of this project is advancing process understanding through multiscale modeling connecting gas phase chemistry with particle aerosol dynamics based on first principles.This project focuses specifically on optical properties of carbonaceous particles due to their impact on climate modeling and fire detection: in specific, on the relation between particle optical properties and their fractal-like structure and composition. For example, nascent soot is transparent to visible light, making it challenging to detect with conventional detectors, while mature soot is a broad band light absorber. So, chemical kinetics will be interfaced with atomistic, mesoscale and continuum models to calculate the evolving soot refractive index accounting for soot morphology & composition. This could help to probe the onset of nucleation and develop more sensitive and selective detectors to sense fire in its early stages. Most importantly, the soot radiative forcing could be derived from first principles, narrowing the current high uncertainty of global models of the soot impact on climate. This project will assist the education of PhD and post-doctoral students specializing in nano-particle processing and allow BSc/MSc students to gain knowledge in analytical methods & particle technology. Results will be presented at international conferences and submitted to refereed journals.
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