http://physics.colorado.edu/phys3070The normal atmosphereThe cast of charactersCarbon MonoxideCO formationCO formationCO formationCO/CO2 conversionCO/CO2 conversionCO/CO2 conversionMaking step 2 more probableHow much is too much?Natural removal methodsReducing CO from carsMethyl Tertiary Butyl EtherMethyl Tertiary Butyl EtherMethyl Tertiary Butyl EtherJudah Levine, 3070L34 1http://physics.colorado.edu/phys3070http://physics.colorado.edu/phys3070Judah LevineJudah LevineJILA SJILA [email protected]@colorado.edu303 492303 492--7785 (27785 (2--7785)7785)M,F 11M,F 11--Noon, W 1Noon, W 1--3 pm3 pmalso by appointmentalso by appointmentJudah Levine, 3070L34 2The normal atmosphereThe normal atmosphereNitrogen 78.08% 780,800 ppmOxygen 20.95% 209,500 ppmArgon 0.93% 9,300 ppmTotal 99.96% 999,600 ppmCO20.0315% 315 ppmJudah Levine, 3070L34 3The cast of charactersThe cast of charactersJudah Levine, 3070L34 4Carbon MonoxideCarbon Monoxide2C + O2→ 2COC + ½O2→ COColorless, odorless, poisonousCreation: Combustion with “inadequate” oxygenGasoline engine, especially when cold orfirst startingWood and coal stoves and fireplaces, somegas appliancesJudah Levine, 3070L34 5CO formationCO formation“Normal” reaction with “adequate” oxygen:C + O2→ CO2Judah Levine, 3070L34 6CO formationCO formation“Normal” reaction with “adequate” oxygen:C + O2→ CO2Reaction with inadequate oxygen:2C+O2→2COC+½O2→COJudah Levine, 3070L34 7CO formationCO formation“Normal” reaction with “adequate” oxygen:C + O2→ CO2Reaction with inadequate oxygen:2C+O2→2COC+½O2→COHow does the carbon “know” if the oxygen is “adequate?”Judah Levine, 3070L34 8CO/COCO/CO22conversionconversionStep 1: Always happens2C+O2→2COC+½O2→COJudah Levine, 3070L34 9CO/COCO/CO22conversionconversionStep 1: Always happens2C+O2→2COC+½O2→COStep 2: happens only if excess oxygen2CO + O2→2CO2Judah Levine, 3070L34 10CO/COCO/CO22conversionconversionStep 1: Always happens2C+O2→2COC+½O2→COStep 2: happens only if excess oxygen2CO + O2→2CO2Implicit conclusion: Oxygen prefers step 1Instead of C + O2→ CO2with some C not reactingJudah Levine, 3070L34 11Making step 2 more probableMaking step 2 more probable1. Increase the oxygen content2. Use a catalystincreases reaction time for CO, NO, …Judah Levine, 3070L34 12How much is too much?How much is too much?Concentration: problems start at about 100 ppm:rush-hour traffic, parking garagesLegal limits: 35 ppm for 1 hour or 9 ppm for 8 hoursTiny compared to concentration of oxygen (200,000+ ppm)Judah Levine, 3070L34 13Natural removal methodsNatural removal methodsCombines with O2in the lower atmosphereCombines with OH in the upper atmosphereMean time 1-2 monthsJudah Levine, 3070L34 14Reducing CO from carsReducing CO from carsCatalytic converters for car exhaustConverts CO to CO2using a hot catalystOxygen sensor on exhaustvaries input mixtureAdd oxygen compounds to fuelsEthanol, MTBE,…Judah Levine, 3070L34 15Judah Levine, 3070L34 16Methyl Tertiary Butyl EtherMethyl Tertiary Butyl EtherOriginally added as replacement for leadAdded to increase oxygen content starting in 1992to comply with requirements of Clear Air Act of 1990Colorado Front Range: November-FebruaryEvening rush-hour at or after sunsetJudah Levine, 3070L34 17Methyl Tertiary Butyl EtherMethyl Tertiary Butyl EtherMTBE is soluble in waterGets into water supply from leaking tanksSanta Monica water supply contaminated in 1996Many other sites have some contaminationJudah Levine, 3070L34 18Methyl Tertiary Butyl EtherMethyl Tertiary Butyl EtherThe choices:Switch to ethanol-based stuff (Colorado)Decrease CO pollution some other wayJudah Levine, 3070L34
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