Modelling ozonolysis in a multi-inlet flow reactor

Mixtli Campos-PinedaGroup Meeting 2

Fall 2016

1 2 3 4 5 76 8 109P

To pump

39.75”

22.75”

Purge N2 Purge N2

Orange: Ozone inlet

Green: Alkene inlet(+ Oxygen during oxygen experiments)

Blue: plugged port (ultratorr+cap)

Multi-inlet flow cell/CRDS cavity

Ozone flow manifold

FMFM

N2 in

Ozone adsorbed

in silica gel

To flow cell

Alkene + N2 + Scavenger flow manifold

FM

FM N2 in

FM

O2 in(oxygen experiments only)

Alkene inTo flow cell

Simulation of the reaction in a flow reactor.

The system of ODEs is solved using an approximation method by the kinetic simulator KINTECUS.

Multi-Inlet Flow Cell (reaction perpendicular to beam)

1 2 3 4 5 76 8 109P

Ozone in

Alkene/Nitrogen/Scavenger in

1 2 3 4 5 76 8 109P

To pump

Pros:• Every segment is independent• No carryover reaction• Simple modelling

Cons:• Turbulence

Multi-Inlet Flow Cell (reaction parallel to beam)

1 2 3 4 5 76 8 109P

To pump

Ozone + Alkene

Ozone

Pros:• Greatly reduced turbulence

Cons:• Measurement is the average of segment concentrations• Initial conditions change for each segments

1 2 3 4 5 76 8 109P

To pump

39.75”

22.75”

Purge N2 Purge N2

Orange: Ozone inlet

Green: Alkene inlet(+ Oxygen during oxygen experiments)

Blue: plugged port (ultratorr+cap)

Multi-inlet flow cell/CRDS cavity

Total flow changes due to ozone addition:

• Ozone “spike” concentration changes• Species concentrations change

We measure averages:

Nozone,average = [O30+(O3

1+(F1/F2)O30)+...+(O3

9+(F9/F10)O30)]/10

Nozone,segment = O3s-1+(Fs-1/Fs)O3

0

Nspecies,segment = (Fs-1/Fs) Nspecies,s-1

Nspecies,average = [∑110

Nspecies,s]/10

0 1E16 2E16 3E16 4E16 5E16 6E16 7E16 8E16 9E16

0.20

0.40

0.60

0.80

1.00

1.20

[CH

2CH

O]/[

CH

2CH

O] 0

Oxygen (molecules/cc)

11/4/16 5/5/16

Vinoxy data (with new experiments from Friday)

OO

+

O3

OCH2CO CH3OH

SOZ

OH

O O

H H

O

O++H2O

P

P

P

P

P

O O +

H H

O

+

P

H H

O

+ 2O2 P

SOZ

P

H H

O

OH

OH + CO

OH

O2

H2OO3

OH

wall

decomp

wall

O

O

CH2OHCH3OH2O

OH

O2

H H

O

+ HO2

OHOH

HO2 + O2P

0.5 OH + P

trans-2-butene ozonolysis mechanism used in KINTECUS (11/06/2016)

2 +H2O+H2C2

1.00 0.1 0.5 0.05 0.07

0.950.05

0.850.15

1.1E-12

2.6E-14

3.6E-15

1.7E-16

7.5E-13

1.9E-16

6.4E-11 1.6E-12

4E-18

370 s-1

1E-15

1E-12

6.12E-15

1.84E-14

3.67E-14

1E-11

9.1E-12

1E-11

10 s-1

10 s-1

1E-11 HCHO + OH HCO + H2O

7.5E-13

0 2 4 6 8 10

0.00E+000

2.00E+013

4.00E+013

6.00E+013

8.00E+013

F

A

CH2CHO

No oxygen

No oxygen

0 2 4 6 8 10

0.00E+000

2.00E+010

4.00E+010

6.00E+010

8.00E+010

1.00E+011

1.20E+011E

A

CH3CHOO

8.45E15 molecule/cc oxygen

0 2 4 6 8 10

0.00E+000

1.00E+012

2.00E+012

F

A

CH2CHO

8.45E15 molecule/cc oxygen

0 2 4 6 8 10-2.00E+010

0.00E+000

2.00E+010

4.00E+010

6.00E+010

8.00E+010

1.00E+011

1.20E+011

1.40E+011

1.60E+011

1.80E+011

E

A

CH3CHOO

8.45E15 molecule/cc oxygen

0 2 4 6 8 106.80E+015

7.00E+015

7.20E+015

7.40E+015

7.60E+015

7.80E+015

8.00E+015

8.20E+015

8.40E+015

8.60E+015

G

A

O2

0.00E+000 2.00E+015 4.00E+015 6.00E+015 8.00E+015 1.00E+0160.0

0.2

0.4

0.6

0.8

1.0

Simulation Exp 11/04/2016

Oxygen (molecule/cc)

[Vin

oxy]

/[Vin

oxy]

0

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

[Vin

oxy]

/[Vin

oxy]

0

Comparison experiment vs simulation

• Vinoxy concentration from modelling much higher:

Yield of vinoxy in model is overestimated Not enough vinoxy depletion channels, or rates underestimated

• Vinoxy depletion by oxygen much higher:

Vinoxy + Oxygen rates overestimated High vinoxy concentration in modelling driving reaction Not enough oxygen depletion channels, or rates underestimated

OO

+

O3

OCH2CO CH3OH

SOZ

OH

O O

H H

O

O++H2O

P

P

P

P

P

O O +

H H

O

+

P

H H

O

+ 2O2 P

SOZ

P

H H

O

OH

OH + CO

OH

O2

H2OO3

OH

wall

decomp

wall

O

O

CH2OHCH3OH2O

OH

O2

H H

O

+ HO2

OHOH

HO2 + O2P

0.5 OH + P

trans-2-butene ozonolysis mechanism used in KINTECUS (11/06/2016)

2 +H2O+H2C2

1.00 0.1 0.5 0.05 0.07

0.950.05

0.850.15

1.1E-12

2.6E-14

3.6E-15

1.7E-16

7.5E-13

1.9E-16

6.4E-11 1.6E-12

4E-18

370 s-1

1E-15

1E-12

6.12E-15

1.84E-14

3.67E-14

1E-11

9.1E-12

1E-11

10 s-1

10 s-1

1E-11 HCHO + OH HCO + H2O

7.5E-13

0 2 4 6 8 10

0.00E+000

2.00E+010

4.00E+010

6.00E+010

8.00E+010

1.00E+011

1.20E+011

E

A

CH3CHOO

Revisiting Criegee Intermediates

What about acetone oxide?

OO

O

+ O3+

0 2 4 6 8 10-1.00E+011

0.00E+000

1.00E+011

2.00E+011

3.00E+011

4.00E+011

5.00E+011

6.00E+011

7.00E+011

G

A

CH3CO2CH3

Parallel

0 5 10

8.60E+011

8.80E+011

9.00E+011

9.20E+011

9.40E+011

9.60E+011

9.80E+011

1.00E+012

1.02E+012

1.04E+012

F

A

CH3CO2CH3

Perpendicular

Summary

Mechanism for t2b need more work!

Time to revisit measurement of CIs