1 Kølemidlers atmosfærepåvirkning – en historisk gennemgang Ole John Nielsen Department of Chemistry, University of Copenhagen

2 Plan Brug af nye kemiske stoffer –Hvad er de atmosfæriske bekymringer Historie Miljømæssige effekter Konklusioner for HFO-1234yf Konklusioner generelt og fremtid

3 Brug af nye kemiske forbindelser Environmental non-ozone depleting short atmospheric lifetime low global warming potential Performance stability compatibility boiling/freezing point Safety low toxicity nonflammable

4 Hvad bekymrer os generelt ved atmosfæriske udslip? 1. Skadelige emissioner og/eller skadelige nedbrydningsprodukter –(lokal-regional-global- direkte påvirkning) 2. Forøgelse af ozon koncentrationen i troposfæren –(lokal-regional-global) 3. Stratosfærisk ozon nedbrydning –(global) 4. Ændring af jordens strålingsbalance = global opvarmning –(global) Hvad er der fælles for disse fire bekymringer ? Der er kemi involveret “Skyldig – indtil det modsatte er bevist"

5 ?

6 Historie: Begyndelsen 1928Thomas Midgeley opfandt CFCer (CF 2 Cl 2 )? 1930Sidney Chapman ”opfandt” Chapman mekanismen som fører til ozonlaget

7 Dette og supersoniske fly ledte til ….. Chapman mekanismens konsekvenser:

8 Stratosfærisk O 3 nedbrydning Paul Crutzen and Harold Johnston: ”katalyse” ? 1970sJames Lovelock: EC detektor og CFC målinger Spørg: “Hvad sker der med …..?” – og få Nobel-prisen “Hvad sker der med CFC-11 (CFCl 3 ) og CFC-12 (CF 2 Cl 2 ) …?”

9 Stratosfærisk O 3 nedbrydning 1974 Rowland and Molina: Stratosfærisk ozon nedbrydning Cl + O 3 → ClO + O 2 ClO + O → Cl +O O + O 3 → O 2 + O Paul Crutzen and Harold Johnston: ”katalyse” ? 1970sJames Lovelock: EC detektor og CFC målinger Spørg: “Hvad sker der med …..?” – og få Nobel-prisen “Hvad sker der med CFC-11 (CFCl 3 ) og CFC-12 (CF 2 Cl 2 ) …?” (Nature, 1974)

10 Det Antarktiske Ozon Hul

11 Stratosfærisk O 3 nedbrydning Paul Crutzen and Harold Johnston: ”Catalysis” ? 1970sJames Lovelock: EC detektor 1974 Rowland og Molina: Ozon nedbrydning Cl + O 3 → ClO + O 2 ClO + O → Cl +O O + O 3 → O 2 + O Joe Farman: Publiserede ozon-hullet 1987Montreal protocol: 1. udgave 1990Montreal protocol: 2. udgave (London) 1992 Montreal protocol: 3. udgave (København) 1995Nobelprisen til Rowland, Molina og Crutzen

12 Virkede Montrealprotokollen?

13 Montreal protokollen medførte bl.a.: Freon-12, CFC-12, CF 2 Cl 2 blev erstattet Hvad kan man gøre for ikke at få Cl i stratosfæren? Nedsætte levetiden HCFC-22, CHFCl 2 og andre Fjerne chlor HFC-134a, CF 3 CFH 2 og andre

14 Hvad bestemmer levetiden af halogenerede forbindelser i atmosfæren? De fotolyseres ikke i den nederste del af atmosfæren ( max typisk ≤ 200 nm) Regner ikke ud da de har lav opløselighed i vand De fjernes ved reaktion med OH hvis de har et H atom, som kan abstraheres: Indsætte H atomer Indsætte æter-bindinger: –O- Indsætte dobbeltbindinger CF 3 H+ OH CF 3+H 2 O

15 Historie – teknologispring? CFC - chlorofluorocarbons HCFC – hydrochlorofluorocarbons (↓O 3 ) HFC – hydrofluorocarbons (↓O 3 ) HFE – hydrofluoroethers (↓O 3 ) HFO – hydrofluoroolefin – ( pas på navnet ) (↓GWP) ?

16 Environmental effects of CFCs and alternatives formellevetidODPGWPPOCPTOXICS CFC-12CF 2 Cl år110890~0None HCFC-22CHClF 2 12 år ~0None HFC-134aCF 3 CFH 2 14 år % TFA HFC-143aCF 3 CH 3 52 år04470~0None HFE-143CF 3 OCH år0756~0None HFO-1234yfCF 3 CF=CH 2 11 dage047100% TFA Nu er det klima som styrer udviklingen – GWP<150

17 IPCC/TEAP, 2005 Direkte strålings påvirkning (klimaeffekt) af alle ODS og forudsigelse for HFCs

18 1.En gas der absorberer infrarød stråling 2.En gas der lever længe nok i atmosfæren 3.Der skal være en vis mængde for at der er en effekt: CO 2, CH 4, halogenerede gasser (freoner), N 2 O, O 3, H 2 O ? Hvad kan man gøre for at mindske virkningen af en drivhus-gas ?

19 IPCC/TEAP, 2005

20 1.En gas der absorberer infrarød stråling 2.En gas der lever længe nok i atmosfæren 3.Der skal være en vis mængde for at der er en effekt: CO 2, CH 4, halogenerede gasser (freoner), N 2 O, O 3, H 2 O ? Hvad kan man gøre for at mindske virkningen af en drivhus-gas ?

21 Environmental effects of CFCs and alternatives formel levetid ODPGWPPOCPTOXICS CFC-12CF 2 Cl år110890~0None HCFC-22CHClF 2 12 år ~0None HFC-134aCF 3 CFH 2 14 år % TFA HFC-143aCF 3 CH 3 52 år04470~0None HFE-143CF 3 OCH år0756~0None HFO-1234yfCF 3 CF=CH 2 11 dage047100% TFA Montreal vs Kyoto? Der er to andre miljømæssige bekymringer man skal være opmærksom på: 1.Troposfæriske ozon 2.Skadelige nedbrydningsprodukter – trifluoreddikesyre - TFA

22 Environmental effects of CFCs and alternatives formellevetidODPGWPPOCPTOXICS CFC-12CF 2 Cl år110890~0None HCFC-22CHClF 2 12 år ~0None HFC-134aCF 3 CFH 2 14 år % TFA HFC-143aCF 3 CH 3 52 år04470~0None HFE-143CF 3 OCH år0756~0None HFO-1234yfCF 3 CF=CH 2 11 dage047100% TFA

23

24 Konklusioner for HFO-1234yf Den atmosfæriske nedbrydning af HFO-1234yf, CF 3 CF=CH 2 er kortlagt Ingen virkning på det stratosfæriske ozonlag. Levetiden i atmosfæren er 11 dage som medfører at GWP er 4. Photochemical Ozone Creation Potential (POCP) for HFO- 1234yf er 7. Betyder at CF 3 CF=CH 2 bidrager ikke til fotokemisk luftforurening. Atmosfærisk nedbrydning af HFO-1234yf, CF 3 CF=CH 2 danner, CF 3 C(O)F som hydrolyserer til CF 3 C(O)OH (trifluoreddikesyre, TFA) i et udbytte på 100%. Der forventes ikke signifikant miljømæssig effekt fra TFA fra det forventede forbrug af CF 3 CF=CH 2.

25 Konklusioner og fremtid Atm. levetider og GWP for halogenerede forbindelser dækker et stort område Det er muligt at lave nye halogenerede forbindelser med langt mindre klimaeffekt end tidligere anvendte forbindelser. Bidraget til den menneskabte ændring af strålingsbalancen fra halogenerede forbindelser kan bringes tæt på nul. HFO-1234yf og andre vil blive brugt i fremtiden Udgifterne vil være en lille del af de samlede udgifter Der bliver brug for mange alternativer mange anvendelser Vi er med til at udvikle nye stoffer og vi bestemmer der nedbrydning i atmosfæren og dermed deres miljøpåvirkning

26 Mike Mads Meshkat Tim Ole John Tak for jeres opmærksomhed

27 Extra Slides

28 The Photochemical Reactor for reaction rates, product distributions and infrared absorption UV-AUV-C Sun lamps Slide by Matthew S. Johnson

29 Other ways of lowering the atmospheric lifetime Insert a double bond Compoundk Cl k OH k O3 τGWP CF 3 CF=CF 2 Mads (2.7 ± 0.3) x (2.4 ± 0.2) x < 3 x d6 CF 3 CH=CFH Roar (4.7 ± 0.2) x (9.3±0.5) x (2.8 ± ) x d6 CF 3 CF=CH 2 Meshkat (6.9 ± ) x (1.06 ± ) x (6.6 ± ) x d4 CF 3 CH=CH 2 Anne (9.0± 1.1) x (1.4 ± 0.3) x (3.5±0.3) x dn.d. CH 3 CH=CH 2 everybody 2.4 x x x hn.d.?

30 IPCC/TEAP, 2005

31 IPCC/TEAP, 2005

32 IPCC/TEAP, 2005

33 IPCC/TEAP, 2005

34 IPCC/TEAP, 2005 Direct radiative forcing of all ODS and projections for HFCs

35 IPCC 2001

36 What determines the importance of a GHG? 1.The intensity and position of infrared absorption 2.The atmospheric lifetime (near term) 3.The amount released EU law will be: GWP 100y < 150 What can we do something about for the halogenated compounds?

37 CFC-11CCl 3 FCFC-115CF 3 CF 2 Cl CFC-12CCl 2 F 2 halon 1301CF 3 Br CFC-113CCl 2 FCClF 2 halon 1211CBrClF 2 HFC-23CF 3 HHFC-227eaCF 3 CFHCF 3 HFC-125CF 3 CF 2 HHFC-236faCF 3 CH 2 CF 3 HFC-134aCF 3 CF 2 HHFC-365mfcCF 3 CH 2 CF 2 CH 3 Replacement of Ozone-Depleting Compounds with hydrofluorocarbons (HFCs) – no Cl! Also GHG Slide by John Owens (3M)

38 Lifetime and GWP of Fluoroalkanes Atm. GWP (IPCC2007) Compound Lifetime (yrs) (100 yr) CF 4 (PFC-14) ,390 CHF 3 (HFC-23) 27014,800 CH 2 F 2 (HFC-32) CH 3 F (HFC-41) CF 3 CF 3 (PFC-116) ,200 CF 3 CHF 2 (HFC-125) 29 3,500 CF 3 CH 2 F (HFC-134a) 14 1,430 CF 3 CH 3 (HFC-143a) 52 4,470 CHF 2 CH 3 (HFC-152a) CH 2 FCH 3 (HFC-161) CF 3 CHFCF 3 (HFC-227ea) ,220 CH 2 FCF 2 CHF 2 (HFC-245ca) CF 3 CH 2 CF 2 CH 3 (HFC-365mfc) CF 3 CHFCHFC 2 F 5 (HFC-43-10mee) ,640 Slide by John Owens (3M)

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40 Potential replacements for CFCs and perfluorocarbons. Perfluoropolyether (PFPE) Hydrofluoroether (HFE) Hydrofluoropolyether (HFPE) Different Fluorinated Ethers Slide by John Owens (3M)

41 Effect of Ether Oxygen on Atmospheric Lifetime Atm.GWP Compound Lifetime (yrs) (100 Yr ITH) CH 3 CF 3 (HFC-143a) 52 4,470alkane CH 3 OCF 3 (HFE-143a) ether CF 3 CFHCF 3 (HFC-227ea) ,220 CF 3 CFHOCF 3 (HFE-227ea) 11 1,500 CF 3 CH 2 CF 3 (HFC-236fa) 240 9,810 CF 3 CH 2 OCF 3 (HFE-236fa) CF 3 CH 2 CHF 2 (HFC-245fa) 7.6 1,030 CF 3 CH 2 OCHF 2 (HFE-245fa2) GWP still too high! Slide by John Owens (3M)

42 R f - O - R h k OH  (GWP) (cm 3 molecules -1 s -1 )(years) n-C 4 F 9 - OCH x (~404) i-C 4 F 9 - OCH x (~404) n-C 4 F 9 - OC 2 H x (~57) i-C 4 F 9 - OC 2 H x (~57) C 4 F 9 -O-(CH 2 ) 3 -O-C 4 F x (n.d.) 5.93 x (55) Atmospheric Lifetimes of Segregated HFEs Slide partly by John Owens (3M)

43 Atmospheric Impact of HFO-1234yf (CF 3 CF=CH 2 ) T.J. Wallington 1, M.D. Hurley 1, M.P.S. Andersen 2, M.S. Javadi 3, O.J. Nielsen 3 1 Ford Motor Company, USA 2 University of California, Irvine, USA 3 University of Copenhagen, Denmark

44 Background CFC-12 (CF 2 Cl 2 ) replaced by HFC-134a (CH 2 FCF 3 ) in 90s. HFC-134a has GWP 100 of 1430 Regulations developed by the European Union require refrigerants with GWPs<150 for all new vehicles by HFO-1234yf (CF 3 CF=CH 2 ) under consideration as replacement for R-134a.

45 Ford Smog Chamber Experimental study of kinetics of reactions with OH radicals, Cl atoms, O 3. Measurement of products of OH radical and Cl atom initiated oxidation. IR spectrum, radiative efficiency, and global warming potential. Trifluoroacetic acid formation and impacts. (delete)

46 Chlorine atom kinetics Cl + CF 3 CF=CH 2 → products(1) Cl + C 2 H 4 → products(2) Cl + C 2 H 2 → products(3) Linear least squares analysis gives k 1 /k 2 = 0.76 ± 0.04 and k 1 /k 3 = 1.38±0.06. Using k 2 = (9.29 ± 0.51) x and k 3 = (5.07 ± 0.34) x gives k 1 = (7.06 ± 0.54) x and (7.00 ± 0.56) x cm 3 molecule -1 s -1. Hence k 1 = (7.03±0.59) x k(Cl + CH 3 CH=CH 2 ) = 2.4 x k(Cl + CF 3 CH=CH 2 ) = (9.07 ± 1.08) x k(Cl + CF 3 CF=CF 2 ) = (2.7 ± 0.3) x Reaction with Cl atoms not major atmospheric loss of CF 3 CF=CH 2.

47 OH radical kinetics

48 Ozone kinetics Pseudo first order decays of CF 3 CF=CH 2 observed in all experiments. Second order plot gives k=(2.77 ± 0.21) x cm 3 molecule -1 s -1. Combining with [O 3 ] = 35 ppb gives lifetime of 13 years with respect to reaction with O 3.

49 IR spectrum, radiative efficiency, and GWP Integrated IR absorption cross section (800–2000 cm -1 ) = (1.63 ± 0.09) x cm molecule -1 Instantaneous cloudy-sky radiative efficiency estimated using method of Pinnock et al. to be 0.22 W m -2 ppb -1. Global warming potential (100 year time horizon) = 4.

50 Oxidation products OH radical initiated oxidation gives CF 3 C(O)F in a molar yield of 91 ± 6%. Atmospheric fate of CF 3 C(O)F is hydrolysis to give CF 3 C(O)OH (trifluoroacetic acid). Oxidation of CF 3 CF=CH 2 gives trifluoroacetic acid in yield close to 100%.

51 Degradation is initiated by reaction with OH radicals (Orkin et al., 1997; Nielsen et al. 2007, Papadimitriou et al.2008) We estimate an atmospheric lifetime of approximately 11 days and a GWP of approximately 4. Papadimitriou et al. (2008) estimated an atmospheric lifetime of approximately 12 days and a GWP of < 4.4. Atmospheric lifetime and GWP of HFO-1234yf are well established. No significant contribution to radiative forcing of climate change. Impact on climate change References O.J. Nielsen, M.S. Javadi, M.P. Sulbaek Andersen, M.D. Hurley, T.J. Wallington, R. Singh, Chem. Phys. Lett., 439, 18 (2007); V. L. Orkin, R. E. Huie and M. J. Kurylo, J. Phys. Chem. A, 1997, 101, 9118–9124; V.C. Papadimitriou, R.K. Talukdar, R.W. Portman, A.R. Ravishankara, J.B. Burkholder, Phys. Chem. Chem. Phys., 10, 808 (2008).

52 HFO-1234yf does not contain chlorine or bromine and hence will not contribute to the well established Cl- and Br-based catalytic ozone destruction cycles. Papadimitriou et al. (2008) concluded that ozone-depletion potential for HFO-1234yf is “nearly zero”. Impact on Stratospheric Ozone References V.C. Papadimitriou, R.K. Talukdar, R.W. Portman, A.R. Ravishankara, J.B. Burkholder, Phys. Chem. Chem. Phys., 10, 808 (2008).

53 CF 3 CF=CH 2 reacts with OH radicals with rate constant of approximately 1.1 x cm 3 molecule -1 s -1 at 298 K. The peroxy radicals formed will oxidize NO 2 which will photolyze and contribute to ozone formation. Using method of Jenkin (1998) the photochemical ozone creation potential (POCP) for CF 3 CF=CH 2 can be estimated to be 7. The POCP for CF 3 CF=CH 2 lies between those for methane and ethane. CF 3 CF=CH 2 is not expected to make a significant contribution to tropospheric ozone formation. Impact on Tropospheric Ozone Derwent, R.G., M.E. Jenkin, S.M. Saunders, and M.J. Pilling, Atmos. Environ., 32, 2429–2441, Hayman, G.D., and R.G. Derwent, Environ. Sci. Technol., 31, , 1997; Jenkin, M.E., Photochemical Ozone and PAN Creation Potentials: Rationalisation and Methods of Estimation, AEA Technology plc, Report AEAT-4182/ 20150/003, 1998

54 Impact of trifluoroacetic acid References Berg. M., S.R. Müller, J. Mühlemann, A. Wiedmer, and R.P. Scharzenbach, Environ. Sci. Technol. 34, , 2000; M.D. Hurley, T.J. Wallington, M.S. Javadi, O.J. Nielsen, Chem. Phys. Lett., 450, 263 (2008); X. Tang, S. Madronich, T. J. Wallington, D. Calamari,, J. Photochem. Photobiol., B 46, 83, (1998); WMO, Scientific Assessment of Stratospheric Ozone: 2006, World Meteorological Organization, Geneva (2007); Frank, H., E.H. Christoph, O. Holm-Hansen, J.L. Bullister, Environ. Sci. Technol. 36, 12-15, Scott, B.F., C. Spencer, S.A. Mabury, and D.C.G. Muir, Environ. Sci. Technol., 40, , 2006; Scott, B.F., R.W. Macdonald, K. Kannan, A. Fisk, A. Witter, N, Yamashita, L. Durham, C. Spencer, D.C.G. Muir, Environ. Sci. Technol., 39, , 2005; Von Sydow, L.M., A.B. Grimvall, H.B. Borén, K. Laniewski, and A.T. Nielsen, Environ. Sci. Technol., 34, , Atmospheric oxidation of CF 3 CF=CH 2 gives CF 3 C(O)OH (TFA). Tang et al. conclude “no significant risk is anticipated from TFA produced by atmospheric degradation of the present and future production of HFCs and HCFCs as there is a fold difference between the PNEC (Predicted No Effect Concentration) and the PEC (Predicted Environmental Concentration)”. Based on risk assessment of CF 3 C(O)OH by Tang et al. (1988) and analysis by WMO (2006), Hurley et al. conclude that “the products of the atmospheric oxidation of CF 3 CF=CH 2 have negligible environmental impact”. It has been shown that trifluoroacetic acid is ubiquitous in precipitation and ocean water even in remote areas (Berg et al., 2000; Frank et al., 2002; Scott et al, 2005, 2006; Von Sydow et al. 2000). Contribution of CF 3 CF=CH 2 expected to be negligible.

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Globale GHG Emissioner % Bidrag på CO 2 basis Ændring siden 1990 CO % CH 4 -18% N 2 O -20% FCs +19% HFCs+154% PFCs -45% SF 6 -62% Hvorfor interesserer man sig for F-forbindelser?

57 IPCC 2007 Halogenerede forbindelser i atmosfæren

58 HFC134a at Mace Head IPCC/TEAP, 2005 BAU and reduced emissions

59 Levetider og GWP af F-forbindelser Forbindelse Atm. Levetid (år) GWP 100 CF 4 (PFC-14) ,390 CHF 3 (HFC-23) 27014,800 CH 2 F 2 (HFC-32) CH 3 F (HFC-41) CF 3 CF 3 (PFC-116) ,200 CF 3 CHF 2 (HFC-125) 29 3,500 CF 3 CH 2 F (HFC-134a) 14 1,430 CF 3 CH 3 (HFC-143a) 52 4,470 CHF 2 CH 3 (HFC-152a) CH 2 FCH 3 (HFC-161) GWP<150

60 Hvad betyder en æter-gruppe for levetiden? Forbindelse Atm. Levetid (år) GWP 100 CH 3 CF 3 (HFC-143a)524,470 CH 3 OCF 3 (HFE-143a) CF 3 CFHCF 3 (HFC-227ea) CF 3 CFHOCF 3 (HFE-227ea) CF 3 CH 2 CF 3 (HFC-236fa) CF 3 CH 2 OCF 3 (HFE-236fa) CF 3 CH 2 CHF 2 (HFC-245fa) CF 3 CH 2 OCHF 2 (HFE-245fa) GWP er stadig for høj!

61 R f - O - R h Atm. Levetid (år) GWP 100 n-C 4 F 9 - OCH i-C 4 F 9 - OCH n-C 4 F 9 - OC 2 H i-C 4 F 9 - OC 2 H C 4 F 9 -O-(CH 2 ) 3 -O-C 4 F ikke bestemt Levetider af andre typer F-ætere

62 CF 3 CX=CYZ Atm. Levetid (dage)GWP 100 CF 3 CF=CF 2 (interessant)186 CF 3 CH=CFH146 CF 3 CF=CH 2 (HFO1234yf)114 CF 3 CH=CH 2 8.5ikke bestemt Effekten af en dobbeltbinding

63 End with the bad news and the good news The Montreal Protocol have reduced net GWP-weighted emissions from ODSs in 2010 by 5-6 times the reduction target of the first commitment period ( ) of the Kyoto Protocol. Greenhouse gases: CO 2, CH 4, N 2 O, HFCs, PFCs, SF 6 G. Velders et al., PNAS, 2007 The Montreal Protocol will have reduced net GWP-weighted emissions from ODSs in 2010 by about 11 Gt CO 2 -eq yr -1.

64 The bad news Montzka et al. GRL : 30% increase in global CO 2 -weighted HCFC emissions. 2007: HCFC emissions were 2.6% of fossil-fuel and cement related CO 2 emissions (30 Gt/yr)

65 Stratosfærisk O 3 nedbrydning P. Crutzen and H. Johnston: ”katalyse” ? X + O 3 → XO + O 2 XO + O → X + O O + O 3 → 2O 2 X = H, OH, NO, NO 2, F, Cl, Br, (og andet ?)

66 Ole John Nielsen 1954 Født, gift og har 2 børn på 20 og 22 år 1973 Begyndte at læse kemi og fysik på KU 1974 Vigtigt atmosfærekemisk år 1978 Færdig som cand scient og læste videre (PhD) på RISØ på på Forskningscenter RISØ Ford’s Forskningscenter i Aachen, Tyskland 1999-? Professor på Kemisk Institut på KU (det bedste) Mit speciale er nedbrydning af stoffer i atmosfæren (hvor hurtigt og hvordan og hvorfor) IPCC – Intergovernmental Panel of Climate Change Nobels Fredspris 2007