The document describes the Holl-Reactor, a two-dimensional reactor design that allows independent control of shear and flow rate. It offers improved reaction control and decreased reaction times, often by orders of magnitude. Several examples are given of reactions showing significantly faster reaction times in the Holl-Reactor compared to conventional stirred tank reactors. The Holl-Reactor enhances a variety of chemistries and can speed up reactions over 100 times.

1. The Holl-Reactor®
for Process Intensification
By Richard Holl, Dipl.-Ing. and Dr.John Cihonski

2. The Holl-Reactor®
• What is it?
– A two-dimensional versus conventional three-
dimensional reactor design where shear (mass
transfer) and flow rate (residence time) are
independently variable.
• Advantages
– Improved reaction control (yield, selectivity).
– Decreased reaction time - often by by 2 to 3
orders of magnitude.

3. Holl-Reactor®

4. Holl-Reactor® at work

5. Holl-Reactor® Basics
Rotor spins inside stator tube
Reactants
in Product out

6. Controllable Input Variables
• Residence time
• Shear gap, rpm, radius
• Feed input
– Number & placement of ports
• Temperature
• Pressure
• Rotor/Stator Orientation
– Horizontal vs. vertical

7. Oleic acid + n-butanol  butyl oleate
• Concentrated H2SO4 used as catalyst
– Two levels (0.5 wt% & 2.5 wt%)
• 15 mol% excess of n-butanol
• Bench top experiments
– Water retained in system
– Temp 70-80 oC
• Holl-Reactor®
– 318 mm rotor/stator gap, 5000 rpm, Shear rate 38,746 s-1
– Reactor Temperature 115 oC (0.5 wt%) or 130 oC (2.5 wt%).
– Reactants introduced separately at RT.
• Note: Decreasing residence time increased yield in Holl-
Reactor®
Example

8. Oleic acid + n-butanol  butyl oleate
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200
%Yield
Time (minutes)
0.5% Benchtop 2.5 wt% Benchtop 0.5 wt% STT 2.5 wt% STT
1 min.
0.5 min.
2 min.
0.5 min.
STT = Holl-Reactor®

9. Oleic acid + 2-ethyl hexanol  octyl oleate
• Catalyst, p-tolulene sulfonic acid monohydrate (0.55 wt%)
• 15 mol% excess of 2-ethyl hexanol
• Bench top experiments
– Water retained in system
• T = 115-120 oC
– Water extracted from system at
• T = 180-185 oC or,
• T = 170-175 oC
• Holl-Reactors® are also called STT® reactors (Spinning Tube in
Tube) and operate typically with
– 380 mm rotor/stator gap, over 5000 rpm
and a shear rate of 43,633 per sec.
– Reactor Temperature 170 oC.
– Reactants are premixed at room temperature into the reactor.

10. oleic acid + 2-ethyl hexanol  octyl oleate
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300 350 400
%Yield
Time (minutes)
BT, T=180-185 C BT, T=170-175 C BT, water retained, T=115-120 C
1 min.
10 min.
3 min.
Holl-Reactor® = STT

11. Comparing propeller-stirred reaction with that in a Holl-Reactor®:
adipic acid + 2-ethyl hexanol  di-octyl adipate
• Adipic acid is a solid (Tm=152 oC)
• Catalyst, 0.2 wt% FASCAT 4102 (butyltin tris 2-ethyl hexoate)
• 7.5 mol% excess of 2-ethyl hexanol
• Propeller-stirred reactor experiment comparison with Holl-Reactor®
– Water retained (T = 120-130 oC)
– Water extracted (T = 185-195 oC)
• Holl-Reactor® performance, see next slide
– 381 mm rotor/stator gap
– Two RPM settings
• 1740 RPM (shear rate =15,184 s-1)
• 2500 RPM (shear rate = 21,817 s-1)
– Reactor Temperature, 180 oC
– Reactants introduced hot
• Adipic acid, T = 195 oC
• 2-ethyl hexanol, T = 175 o

12. Adipic acid + 2-ethyl hexanol  dioctyl adipate
in a Holl-Reactor® (red dots)
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300 350 400
%Yield
Time (minutes)
BT water retained, T= 120-130 C BT water extracted, T = 185-195 C
1.5 min.,
1740 rpm
1.5 min.,
2500 rpm
Holl-Reactor®
Stirred Reactor

13. succinic acid + propylene glycol  propylene succinate
oligomer
• Holl-Reactor®
– 381 mm rotor/stator gap, 5000 rpm, Shear rate 43,633 s-1
– Reactor temperature, 170 oC
– Reactants premixed as a slurry and introduced at RT.
• Model system for a number of aromatic diacids
• Succinic acid can dissolve but not melt (Tm=188 oC)
• Catalyst, 0.3 wt% FASCAT 4102 (butyltin tris 2-ethylhexoate)
• 10 mol% excess propylene gylcol
• Bench top experiment
– Water retained (T = 135-145 oC)

14. succinic acid + propylene glycol 
propylene succinate oligomer
0
10
20
30
40
50
60
70
0 50 100 150 200 250 300 350 400
%Yield
Time (minutes)
BT water retained, T=134-145 C STT, T=170 C
10 min.
3 min.
Holl-Reactor® = STT

15. Holl-Reactors®
significantly enhanced the following chemistries:
• Esterification, transesterification and polyester synthesis
• Saponification
• Polymerization – multiple monomer mixtures
• Partial selective oxidations
• Epoxide Carbonation
• Amino acid synthesis
• Condensation
• Coupling
• Particle synthesis
• Biocatalysis

16. Conclusion
Holl-Reactors® can speed
up chemical reactions over
a 100 times or more.

17. Holl Partners LLC
www.hollpartners.com