ozonolysis of tme

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1. Ozonolysis of 2,3-dimethyl-2-butene Group Meeting Winter 2015 2. Outline Motivation Experimental Setup Results Future Work 3. Motivation One of the most important processes of Volatile Organic Carbons (VOCs) in the atmosphere is oxidation. One of the main oxidation reactions of VOCs is ozonolysis. 4. Carbonyl oxides, also know as Criegee Intermediates (CIs), are produced by ozonolysis through the breaking of a primary ozonide (POZ). 5. CIs are formed with a energy distribution that results in only a fraction undergoing reactions or rearrangements. Resulting in short lifetimes. 6. Rearrangement, decomposition, or reaction of carbonyl oxides in the atmosphere produces secondary organic aerosols, OH radicals, peroxy radicals, etc. 7. Experimental Setup Ozonolysis of alkenes is done using a flow reactor: Reaction products are measured using cavity ring-down spectroscopy (CRDS). Spectra of the main products is subtracted in order to look for CI features. 8. CRDS: Suitable for atmospheric measurements due to: Long sample path (high sensitivity). Real time measurements. Portability (in situ measurements). 9. Spectra analysis: n i ii N L dc L dc 0 11 10. 318 320 322 324 326 0.15 0.20 0.25 0.30 0.35 0.40 0.45 Exp Synth )( 11 0 fNNN L dc acacformformozoz 11. + O3 + 12. Simulation of the reaction in a flow reactor. The system of ODEs is solved using an approximation method by the kinetic simulator KINTECUS. 13. # k Reaction Comments 1.13E-15 C6H12+O3==>CH3COCH3+0.85CH3COOCH3+0.15CH3CO2CH3 1 2.50E+05 CH3COOCH3==>CH3+CH3+CO2 18 7.80E+05 CH3COOCH3==>CH3COCH2+OH 19 5.00E+04 CH3COOCH3==>CH3OCOCH3 20 1.70E+05 CH3COOCH3==>CH3O+CH3+CO 21 4.40E+05 CH3COOCH3==>CH3O+CH3CO 22 1.10E+05 CH3COOCH3==>CH3OCO+CH3 23 9.13E-13 CH3+O3==>CH2O+H+O2 2 4.50E-11 CH3+CH3O==>CH2O+CH4 3 1.49E-15 CH3O+O2==>CH2O+HO2 4 2.49E-11 CH3O+CH3O==>CH2O+CH3OH 5 4.98E-11 CH3O+OH==>CH2O+H2O 6 1.19E-10 OH+C6H12==>C6H12OH 7 1.39E-11 OH+CH2O==>H2O+HCO 8 1.49E-13 OH+CO==>CO2+H 9 3.82E-13 H+C6H12==>C6H13 10 2.66E-11 H+O3==>OH+O2 11 5.65E-12 HO2+HO2==>H2O2+O2 12 7.97E-11 HO2+OH==>H2O+O2 13 1.66E-12 HO2+CH3O==>CH3OH+O2 14 4.90E-20 CH3CO2CH3 + C6H12 ==> CH3COCH3+C6H12O 15 1.00E-12 CH3CO2CH3 + O3 ==> CH3COCH3+O2+O2 16 3.00E-11 CH3CO2CH3+CH3==>CH3COCH3+CH3O 17 4.00E-11 CH3CO2CH3 + CH3CO2CH3 ==> CH3COCH3+CH3COCH3+O2 C1 5.00E-12 CH3CO2CH3+HO2==>CH3COOCH3HO2 C2 - DUMMY 14. fNNN L dc acacformformozoz 0 11 Results 15. Difference spectrum n i iiacRacCOOCHCOOCH NNNf ,2323 16. Scavenging with HFA n i iiHFARHFAacRacCOOCHCOOCH NNNNf ,,2323 17. [Difference spectra] 18. Scavenging with SO2 fNNNN L dc acacSOSOformformozoz 22 0 11 19. Difference spectrum n i iiacRac NNf , 20. Why? # k Reaction Comments 1.13E-15 C6H12 + O3 CH3COCH3 + 0.85CH3COOCH3 + 0.15CH3CO2CH3 1 4.90E-20 CH3CO2CH3 + C6H12 CH3COCH3 + C6H12O 15 1.00E-12 CH3CO2CH3 + O3 CH3COCH3 + O2 + O2 16 3.00E-11 CH3CO2CH3 + CH3 CH3COCH3 + CH3O 17 4.00E-11 CH3CO2CH3 + CH3CO2CH3 CH3COCH3 + CH3COCH3 +O2 C1 5.00E-12 CH3CO2CH3 + HO2 Products C2 5.00E-12 CH3CO2CH3 + OH Products C3 4.00E-14 CH3CO2CH3 + CO CH3COCH3 + CO2 C4 6.00E-13 CH3CO2CH3 + CH3COCH3 CH3CO2CH3CH3COCH3 C5 3.50E-11 CH3CO2CH3 + SO2 CH3CO2CH3SO2 C6 21. C6H12 O3 CH3COCH3 CH3COOCH3 CH3CO2CH3 CH2O CH3CO2CH3CH3COCH3 SO2 CH3CO2CH3SO2 no SO2 2.71E+16 8.26E+13 5.87E+14 5.96E+07 3.45E+10 2.37E+14 6.35E+13 0 0 with SO2 2.71E+16 8.26E+13 6.10E+14 5.87E+07 9.58E+08 2.41E+14 1.83E+12 5.45E+14 8.90E+13 1/t change 1.21E-03 sCI-SO2 adduct contributes to the signal Initial SO2 Final SO2 Simulation SOZ 2.90E+14 2.20E+14 4.20E+14 3.50E+14 5.50E+14 3.60E+14 6.60E+14 5.00E+14 7.90E+14 6.00E+14 22. Measuring SO2 23. Scavenging with different amounts of SO2 24. Difference Spectra 25. Change in difference spectra with different initial SO2 26. Future Work Fix flow fluctuations of SO2 Try more initial SO2 concentrations Search for SOZ spectra Try ethene ozonolysis using SO2 as scavenger


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