Nanoparticles: Dry Synthesis and Applications
Sunday May 20, 2007, 8:00 am - 6:00 pm, Santa Clara, California
We will start with the history of this fascinating technology from ink
production in ancient China and Greece to the Bible printing by
Gutemberg in Mainz and to the current manufacture of optical fibers,
carbon blacks, filamentary nickel, pigments and fumed silica through
valiant Edisonian research highlighting limitations and opportunities
for synthesis of new functional materials. An overview of flame and
hot-wall reactors for synthesis of metal, alloys, ceramics as well as
their composites will be discussed. The fundamental physical and
chemical phenomena that control these processes are summarized.
Principles for designing these processes by combining fluid and particle
dynamics are presented. Emphasis is placed on scalable flame reactors
that dominate the value and volume of today’s manufacture of
nanostructured materials. In particular, it is highlighted the
versatile flame spray pyrolysis process for synthesis of catalysts
(CeO2/ZrO2, Pt/Al2O3, TiO2/SiO2), ZnO quantum dots for UV-filters, mixed
ceramics such as translucent and radio-opaque Ta2O5/SiO2 and others.
Synthesis of solid nano- or hollow micro-particles of Bi2O3, CeO2 or
Al2O3 by combustion spraying of solutions, emulsions or slurries will be
shown along with process design criteria. Next, the course highlights
specific cases for hot-wall synthesis of selected metals (Al, Bi, Pd and
Zn) and even co-production of solar H2. Scale-up will be discussed
showing how design correlations are developed with reactors of various
sizes along with principles for synthesis of hard- or soft-agglomerates.
Coating of nanoparticles with oxide or carbon films in flame and hot
wall reactors will be discussed.
A scalable, dry technology for synthesis of high purity nanoparticles
with closely controlled characteristics is presented. This is
advantageous over classic wet chemistry technologies (sol-gel or
precipitation) as it does not use their multiple processing steps (e.g.
washing, drying, calcinations etc.) and high volumes of liquid
byproducts. Today industry uses dry technology for manufacture of
carbon blacks and simple oxides after several years of evolutionary
research. As a result, it is practically impossible to use these units
for synthesis of functional inorganic (mixed ceramic or metal-ceramic)
nanoparticles without going through the same costly and time-consuming
cycle as shareholders have no patience or stomach for it. Major
breakthroughs in academia, however, recently have placed dry synthesis
of nanoparticles on a firm scientific basis allowing now synthesis of
these materials in appreciable volumes and competitive prices creating
renewed interest in dry processes and products. The focus now shifts to
an integrated process development focusing on final product performance
rather than particle characteristics through close interaction of
particle specialists with end users. Special emphasis is placed on the
degree of particle agglomeration and its control as well as on
nanoparticles with designed morphology and even layered composition for
materials that people never thought that could make them just a few
This course will introduce this technology and show its accessibility
and potential for manufacture of functional nanoparticles. It will go
through its history to show how it survived the “death valley” from the
laboratory to manufacturing for selected products. The most important
theories will be given accompanied with tangible examples so one can
approach a specific problem with systematic reasoning and full
utilization of the literature. Diverse examples will be given through
analyzing and discussing a number of new products and processes using
dry technologies in a relaxed atmosphere and through motivating lectures.
1. Overview and History (1h)
Nanoparticles: Origins, Significance and Applications. Is it a Bubble?
Health Issues. Cost. The evolution of today’s industry for manufacture
of carbon blacks, fumed silica, pigmentary titania, ZnO, filamentary
nickel, optical fibers and, most recently, for metallic and ceramic
nanoparticles. Pros and Cons of Current Processes: Flame and Hot-Wall
2. Fundamentals (1h)
Definitions and Particle size Distribution. Brownian Motion and Particle
Diffusion. Thermophoretic Sampling and Particle Characterization.
Aerosol Coagulation in the Continuum and Free-Molecular Regimes,
Self-Preserving Distributions, Agglomeration, Fractal-like Particles.
Critical, Kelvin or minimum Particle Size, Condensation and Nucleation.
3. Principles for Process Design and Operation (1.5h)
Controlled flame synthesis of nanoparticles. Chemistry affects particle
characteristics. Reactor design by computational fluid and particle
dynamics. Process Scale-up and correlations. Hard- and Soft-Agglomerates.
4. Novel Products and Applications (2.5h)
4.1 Flame-made catalysts for DeNOx removal (V2O5/TiO2), polymer
synthesis (TiO2/SiO2) and chiral pharmaceuticals (Pt/Al2O3) manufacture,
Pt/Ba/Al2O3 for NOx storage, automotive CeO2/ZrO2 as well as
photocatalysts (Pt/TiO2 or Ag/ZnO)
4.2 Mixed ceramics: Stable ZnO Quantum Dots for UV-filters by doping
with silica, Dental nanocomposites (non-agglomerated SiO2) or
Translucent Ta2O5/SiO2 in polymer matrices.
4.3 Hot-wall reactors for metal (Bi, Pd, Al, Zn) and non-oxide (AlN,
B4C) nanoparticles and even for co-production of solar H2 with Zn/ZnO
4.4 Coatings: Carbon or ceramic oxide films on titania or silica
4.5 Sensors: Flame synthesis of sensing particles for organics (TiO2)
and their direct deposition (Pt/SnO2) on electrodes resulting in highly
accessible porous films and sensors.
4.6 Solid or hollow ceramic particles and nanorods by emulsion/solution
Who Should Attend
The course is aimed for scientists (chemistry and physics) and engineers
(chemical -mechanical) in research and development of processes
involving fine particles for batteries, films, phosphors, catalysts,
polishing, medical and dental nanocomposite materials (prosthetics),
pigments, optical fibers, precious metals (Ag, Au, Pt, Pd), sunscreens,
cosmetics, fuel cells, solar energy storage.
Dr. Sotiris E. Pratsinis (PhD UCLA 1985) is Professor of Process
Engineering (www.ptl.ethz.ch) at the Swiss Federal Institute of
Technology (ETH Zurich), Switzerland since 1998. His research centers
on aerosol processing of nanoparticles with applications in catalysts,
ceramics, sensors, batteries, dental and food materials. His program
has been funded by the U.S. and Swiss National Science Foundations as
well as by DuPont, Nestle, Toyota, Ivoclar-Vivadent etc. Prior to this
he was Professor and Interim Head of Chemical Engineering at the
University of Cincinnati, Ohio (1985-98). Prof. Pratsinis has graduated
16 and currently supervises nine PhD students with whom he has published
over 200 refereed articles and book chapters on synthesis of
nano-TiO2, SiO2, ZnO, CeO2 as well
nanocomposites, lightguides and noble metal — ceramics. He has
also six patents licensed to Dow Chemical, Degussa and Hosokawa-Micron.
He has received the 1988 Kenneth T. Whitby Award of the American
Association for Aerosol Research, the 1989 Presidential Young
Investigator Award by the U.S. National Science Foundation and the 1995
Marian Smoluchowski Award by the European Aerosol Association and the
2003 Thomas Baron Award by the American Institute of Chemical Engineers
(AIChE). He is European Editor of the Journal of Nanoparticle Research
and on the Editorial Boards of the Powder Technology, Journal of
Aerosol Science, Advanced Powder Technology, Particle and Particle
Systems Characterization and KONA Powder and Particle as well as on the
Advisory Board of the Australian Research Council Centre on Functional
Nanomaterials and on the Science Advisory Board, Harvard School of
Public Health - International Initiative for the Environment and Public