1. PDMS process overview
化工四
B 彭子軒
B 劉邦彥
B 林文翔

2. Solid transport to reactor in Rochow synthesis process
Screw conveyor
Pneumatic conveyor
Easy to control the flow rate
The material need to be fluidized
Low capacity
Particle range 20~5000 μm
Transport distance is short
Transport distance is long
Can be cooling or heating
high energy cost
Dp of our Silicon particle is 100~6000 mesh
=>Dp = 0.55~33.33 μm
(1 μm = 180 mesh)
Screw conveyor

3. The reactor for Rochow synthesis --- fluidized bed reactor
Bed hight=?
Trying to estimate the packed height and the reactor volume are both our goals.
Mass flow rate=?

4. PDMS synthesis Target: linear PDMS
Origin ,functionality ,and field of application of silicone structural units

5. : = 1:1 Previous step Hydrolysis: Cyclic D4~7
linear Dn (n=4~100,molarcular weight distribution is very wide.)
BUT… :
= 1:1
This is a BAD news!!!

6. The monomer synthesis and polymerization process
D4 and D5 are main products
1. Cyclization process:
2. Ring-opening polymerization process:
D4 and D5 are major industrial products ,which are either marketed as such or used for the production of PDMS

7. Flow chart Hydrolysis DMDCS Rochow synthesis Cyclization DMDCS
Methanolysis
D4 +D5 Si
CH3Cl
( We have another choice.)
Ploymerization
The Methanolysis process is:
DMDCS + CH3OH --> Dn + H(Dn)OH + CH3Cl + H2O
PDMS
(CH3)2SiCl2  2CH3Cl + Si/Cu2O

8. Methanolysis or Hydrolysis
Methanolysis: DMDCS + CH3OH  Dn + H(Dn)OH + CH3Cl + H2O
Hydrolysis: DMDCS + H2O  Dn + H(Dn)OH +HCl
Easy to saparate.
Don’t forget that CH3Cl ,the product in Methanolysis process ,which can be the raw material of Rochow direct synthesis.
To transport this strong acid is so expansive.
raw material
Market price
chloromethane
3.5RMB/kg
methanol
2.5RMB/kg
Raw material cost is saved at least 30%

9. The flow chart becomes…
DMDCS
Rochow synthesis
Methanolysis
Cyclization
CH3OH
D4 +D5 Si
CH3Cl
Ploymerization
The Methanolysis process is:
DMDCS + CH3OH --> Dn + H(Dn)OH + CH3Cl + H2O
The Rochow synthsis process is :
2CH3Cl + Si/Cu2O → (CH3)2SiCl2
PDMS

10. Previous Question Cyclone: centrifugal settling Axial velocity
Big particles are settled down
Axis
Wall(r=R)

11. Future work Methanolysis process design Cyclization process analysis
Polymerization process analysis
Polymer transportation

12. References