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Investigation of Thermo-Gravimetric Analysis (TGA) on Waste Tires and Chemical Analysis Including Light Hydrocarbon, Substituted
Aromatics, and Polycyclic Aromatic Hydrocarbon (PAH)
Eilhann KwonDepartment of Earth and Environmental Engineering (HKSM)
Columbia University, New York, NY, 10027
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Presentation Outline
• Introduction & Background• Experimental Setup• Previous work• Results• Conclusions & Future Work
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Objectives
• Characterize the thermal degradation mechanisms of a waste tire in the combustion and pyrolysis process
• Identify by-products from the thermal degradation of a waste tire
• Investigate air pollutant generation mechanism from the combustion and pyrolysis process
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Feasibility of Waste tires as fuel
Heating Value of Fuels*
Fuel Heating Value (Btu/lb) Peat 2,500-6,500Wood 6,500Coal 8,000-14,500
Gasoline 20,400Diesel 19,300
Tire 12,000-16,000
* Source: NIST Chemistry WebBook
OilofBarrelmillionyrBTUnquadrillio
lblbBTU
12/ 09.0
1029320000,15 6
≈≈
×××≈
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Assumption• Avg. Wt. of a waste tire: 20lbs• Experimental heating value of a waste
tire: 15,000Btu/lb• Waste Tire generation a year: 293million
Introduction
Landfill/Stockpile• 75% Void Volume
– Needs high cost of tipping fees– Leads to extremely difficult conditions
for quenching tire fires– Causes the piercing the landfilling cover
• Non-biodegradability• Leachate
Waste tire generation (293 million waste tires in U.S.)1 waste tire / 1 person / 1 year
Utilization Alternatives(Combustion & Gasification/Pyrolysis)
LandfillStockpiles
LandfillStockpiles
CombustionPyrolysis
Recycle
Recycle
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Source: EPA & Rubber Manufacturer Association
Overall Experimental Setup
15th NAWTEC, MAY 21-23, 2007, Miami, FL
N2
80ml/min
20ml/min
Heated tubing (280oC)
Micro-GC & GC/MS
Mass Flow Controller
Certified gases (pure and mixtures)
Const. Temperature
Water circulation
O2 Air
Experimental ConditionsCurrent conditions found in combustors
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Air atmosphere (21% O2, 79% N2)
Lean atmosphere (7% O2, 93% N2)
Gasification/ pyrolysis (100% N2)
Enriched atmosphere (30% O2, 70% N2)
Possible enhancements for higher efficiency
Properties of a Tire
Cross section of a tire Main constituents of rubber(Approximately 60%)
C C
CH2
H3C
H2C
H
**
n
*
HC
CH
H2C
CH2
HC
CH
H2C
CH2
CHCH2
H2C
CH
HC
*
n
C C
CH2
H
H2C
H
**
n
Natural Rubber(Poly-Isoprene)
Butyl Rubber
Styrene-Butadiene Rubber (SBR)25 wt% of Styrene+75wt% of Butadiene
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Previous Work
Thermo-gram of SBR and IR in various atmospheres at 20oC/min heating rate
15th NAWTEC, MAY 21-23, 2007, Miami, FL
SBR IR
Wei
ght L
oss F
ract
ion,
α[-
]
Wei
ght L
oss F
ract
ion,
α[-
]
Location of Epoxyethane in the Region of the Decomposition Plateau
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Marco J. Castaldi and Eilhann Kwon, “Beneficial Use of Waste Tires: An Integrated Gasification and Combustion Process Design via Thermo-Gravimetric Analysis (TGA) of Styrene-Butadiene Rubber (SBR) and Poly-Isoprene (IR)”, EES , In pressing, 2007
Characterization of Thermal Degradation of Tires
Temperature, [oC]
0 200 400 600 800 1000
Wei
ght L
oss,
[%]
0
20
40
60
80
100
100% N2 Atmosphere7% O2 & 97% N2
Air Atmosphere30% O2 & 70% N2
Heating rate: 10oC/min
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Volatilization + Oxidation
SEM/EDX Analysis
1000oC in N2 500oC in lean air 700oC in lean air 1000oC in lean air
Temperature (oC) Atmosphere C Wt % S Wt%25oC air 94.14% 2.6%
1000oC N2 93.19% NA500oC 7% O2 & Bal. N2 93.48% NA700oC 7% O2 & Bal. N2 88.15% NA
1000oC 7% O2 & Bal. N2 31.42% NA
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Chromatogram from a Tire at 400oC in N2 Atmosphere
Chromatogram from SBR Chromatogram from IR
Chromatograms from the thermal degradation of a Tire
Isoprene
Toluene EthylbenzeneStyrene
Styrene
1-methyl-4-(1-methylethyl)-benzene
Limonene
Limonene
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Concentration Profiles of Styrene & Limonene
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Heating rate: 20oC/min
Proposed Limonene Formation MechanismEquilibrium geometry based on Hartree-Fock approximations using the 3-21G method
Modeling using SPARTAN, Wavefunction Inc.
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Chromatogram from IR in N2 Atmosphere
Isoprene
Limonene
Qualitative GC/MS Results from a tire in Air
Chemical Species (M.W) Chemical Species (M.W)
Methane (16) 2-methyl-1-buten-3-yne (66)
Acetylene (26) Octane (114)
Ethane (30) 4-octene (112)
Propane (44) n-dodecane (170)
n-Butane (58) Ethanol (46)
But-1-ene (56) Cyclohexanol (112)
1,3-butadiene (54) 1-pentanol (88)
Pentane (72) 1-cyclopropyl-ethanone (84)
1-pentene (70) Octanal (142)
1,4-pentadiene (68) Propanone (142)
Hexane (86) Acetone (58)
1-Hexene (84) 2-Decanol (158)
Cyclohexene (82) 1,3-Butadienal (68)
1,1-dimethyl-cyclopropane (72) 3-Butene-2-one (70)
3-methyl-2-pentene (84) Buanone (72)
2-methyl-1-pentene (84) Hexanol (102)
1-methyl-cyclopentene (82) 3-Methyl Butanol (88)
4-methyl-cyclopentene (82) Thiophene (84)
Cyclopentene (68) Benzoic Acid (122)
2-pentyne (68) Benzaldehyde (106)
Hydrocarbons
Partial OxidationAlcohol
Aldehyde
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Concentration Profiles of Phenol in Various Atmospheres
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Concentrations of Chemical Release from a TGA Unit with a Tire at heating rate 10oC/min in air
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Concentration Profiles of Phenyl-C2-3 and Phenyl-C4from a tire in 30% O2 and Bal. N2 Atmosphere
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Precursors to the formation of PAHStructure breakdownGas phase addition of reactive
intermediates
Hexylbenzene
1,2,4-triethylbenzene
1,3,5-triethylbenzene
Concentration Profiles of Phenyl-C6 from a tire in 7% O2 and Bal. N2 Atmosphere
15th NAWTEC, MAY 21-23, 2007, Miami, FL
The Origin of Benzene DerivativesMain pathway to form benzene derivatives from SBR
15th NAWTEC, MAY 21-23, 2007, Miami, FL
The Origin of Benzene Derivatives
Diels-Alder Reaction
From the thermal degradation of IR
Diels-Alder ReactionFrom SBR backbone
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Concentration Profiles of Naphthalene with a Tire in Various Atmospheres
15th NAWTEC, MAY 21-23, 2007, Miami, FL
CH3
H3C
CH3
H3C
H3C
Concentration Profiles of 2 and 3 ring at 10oC/min Heating Rate in Air Atmosphere
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Conclusions
• Volatilization and combustion was observed simultaneously when oxygen presented.
• The bond scission followed by hydrogenation was observed in monomer of main constituents of a tire
• The Hierarchical step for growing benzene derivatives by gas phase addition also observed.
• The oxidized benzene derivatives such as phenol reached up to 30PPMV in enhanced air atmosphere and the secondary oxidized chemical species derived from phenol such as benzaldehyde were observed.
• Oxidation is the feasible way to reduce the level of hazardous air pollutants including VOCs and PAHs.
• The chemical analysis from different ratio between SBR and IR in various atmospheres should be carried out.
15th NAWTEC, MAY 21-23, 2007, Miami, FL
Future Work
• Determine and develop the higher efficiency and lower emission firing technology.
15th NAWTEC, MAY 21-23, 2007, Miami, FL
AcknowledgementMarco J. Castaldi
15th NAWTEC, MAY 21-23, 2007, Miami, FL