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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 Kwon Department 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 2,500-6,500 Wood 6,500 Coal 8,000-14,500

    Gasoline 20,400 Diesel 19,300

    Tire 12,000-16,000

    * Source: NIST Chemistry WebBook

    OilofBarrelmillion yrBTUnquadrillio

    lblb BTU

    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)

    Landfill Stockpiles

    Landfill Stockpiles

    Combustion Pyrolysis

    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 Conditions Current 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

    H2 C

    H

    **

    n

    *

    H C

    C H

    H2 C

    C H2

    H C

    C H

    H2 C

    C H2

    CH C H2

    H2 C

    C H

    H C

    *

    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

    W ei

    gh t L

    os s F

    ra ct

    io n,

    α [-

    ]

    W ei

    gh t L

    os s F

    ra ct

    io n,

    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

    W ei

    gh t L

    os s,

    [% ]

    0

    20

    40

    60

    80

    100

    100% N2 Atmosphere 7% O2 & 97% N2 Air Atmosphere 30% 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% NA 500oC 7% O2 & Bal. N2 93.48% NA 700oC 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 Ethylbenzene Styrene

    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 Mechanism Equilibrium 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 Oxidation Alcohol

    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-C4 from a tire in 30% O2 and Bal. N2 Atmosphere

    15th NAWTEC, MAY 21-23, 2007, Miami, FL

    Precursors to the formation of PAH Structure breakdown Gas 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 Derivatives Main 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 Reaction From 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

  • Acknowledgement Marco J. Castaldi

    15th NAWTEC, MAY 21-23, 2007, Miami, F