1 L reactor

1
1 L reactor

• Itaconic acid in toluene used as a model system

A broad band transducer was attached to the wall
of a jacketed glass reactor.
2
Transducer(impulse response test)
cubic spline of average of 20 spectra
Although the transducer has a broadband response,
there are frequencies where the sensitivity is
poor (around 50 and 200 kHz).
3
Vessel, amplifier and transducer(impulse
response test)
cubic spline of average of 10 spectra
The overall response of the system is influenced
by the filtering effects of the vessel and
amplifier. This slide shows an overlay of the
system response and the signal obtained for
itaconic acid particles stirred in toluene.
4
Itaconic acid in 500 mL toluene
Stir rate 250 rpm Oil temp 20 C
As the amount of particles increases, there is a
linear increase in the magnitude of the signal
across the frequency range.
5
Effect of particle size - spectra
When the same amount of itaconic acid is used,
but of different particle size range, the signal
does not change significantly in the region
200-300 kHz. It should be possible to extract
both particle concentration and particle size
information from broadband acoustic signals of
this type.
6
Heterogeneous reaction

• Esterification of itaconic acid with 1-butanol in
  toluene used as a model heterogeneous reaction

The esterification of itaconic acid was monitored
using passive acoustic emission. The ester
products are soluble in toluene where as the
itaconic acid is only sparingly soluble.
7
Total ester concentration - HPLC
Itaconic acid (gt500 mm to lt853 mm)
11, 70 C
Progression of the reaction can be followed by
extracting samples for analysis by HPLC this is
not particularly convenient.
8
Acoustic emission broadband transducer
Itaconic acid (gt500 mm to lt853 mm)
11, 70 C
When itaconic acid particles in the range stated
were reacted, the acoustic signal in the 60-585
kHz region decreased during the reaction (which
was deliberately sub-stoichiometric).
9
Change in itaconic acid particle size
Itaconic acid (gt500 mm to lt853 mm)
11, 70 C
By comparing changes in the ratio of the peaks in
the regions identified in slide 5, it was
possible to monitor changes in particle size
during the reaction. All of the data (Acoustic
and HPLC) indicates that the reactions reached an
end point around 80 mins.
10
Conclusions

• Signal transmitted through and around vessel wall
  ? not just from particulates close to the
  transducer
• Between run repeatability affected by variability
  of transducer attachment
• Acoustic signals sensitive to temperature, stir
  rate, and particle size and concentration
• Broadband signals contain both particle size and
  concentration information
• Mean particle size determined for mixtures
• Decrease in particle size detected during
  reaction
• Further work required to separate the two effects