(64b) Production of Zirconia Nanoparticles Using a Microreactor with Same Axle Dual Pipe

We
have developed a microreactor with same axle dual pipe, by which a uniform
nano-particles with sphere shape can be produced without adhesion of particles
to wall.  By using the microreactor, we have previously shown
that uniform titania nano-particles with sphere shape of desired
particle size
could be designed
by changing the mean residence time and the channel size.  In
this study, we extended to the above microreaction technology to nano-particle
formation with more rapid reaction rate. As a representative
example, zirconia particles were produced by supplying zirconium tetrabutoxide solutes to
the inner tube and alcohol/water mixture to the outer tube.  We examined
the effect of solvent and alcohol type, the micro channel size and the
residence time on particle properties.

Zirconia particles
were produced and grown in an inner fluid and no precipitation of particles was
observed at the wall by sealing of an outer fluid.  The size and shape of
produced zirconia particles significantly differed with the solvent and alcohol
type. Only when ethanol was used as a solvent of zirconium tetrabutoxide,
spherical
zirconia particles were produced.  As carbon number of alcohol used
increased, the mean size of particles increased and its distribution became
broad.  When ethanol was used as a solvent for diluting water, the
zirconia particles had sharp and narrow distribution which could not be
realized by
the conventional batch method.  In addition, the mean particle size was
successfully controlled in the range from 4nm to 700nm merely by changing the
mean residence time and the concentrations of zirconium tetrabutoxide and water in
the presence of a dispersant, polyethyleneimine. From these results, it was
clarified that the microreaction technology with same axle dual pipe was one of
attractive methods to produce uniform nano-particles in a wide range by
controlling the nucleation and the aggregation processes in a precise diffusion
control regime.