Modeling Gas-Phase Chemistry and Heterogeneous Reaction of Polycyclic Aromatic Compounds

EPA Grant Number: R824970C007
Subproject: this is subproject number 007 , established and managed by the Center Director under grant R824970
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EERC - Center for Airborne Organics (MIT)
Center Director: Seinfeld, John
Title: Modeling Gas-Phase Chemistry and Heterogeneous Reaction of Polycyclic Aromatic Compounds
Investigators: Howard, Jack B. , Pope, C. J.
Current Investigators: Howard, Jack B.
Institution: Massachusetts Institute of Technology
EPA Project Officer: Hahn, Intaek
Project Period:
Project Amount: Refer to main center abstract for funding details.
RFA: Center on Airborne Organics (1993) Recipients Lists
Research Category: Targeted Research

Objective:

The objective of this project is to enhance predictive capabilities of the previously developed model for polycyclic aromatic hydrocarbons (PAH) formation, for use in source attribution studies and in the development of emission control strategies.

Approach:

A predictive model of PAH formation in flames is being developed using elementary reactions to describe the basic flame chemistry and PAH growth -up to a mass of 400 amu, and aerosol dynamics to describe all species (both PAH and soot) with masses above 400 amu. Sectional aerosol equations for soot formation, growth, and oxidation are expressed in a form suitable for concurrent soot aerosol modeling and detailed gas-phase kinetic modeling. The soot model predicts the effects of soot upon the concentrations of gas-phase species, including PAH of interest. Predictive capability of the combined model is being improved by inclusion of more 2-6 ring PAH, especially those containing 5membered rings (some of which are known toxics), use of more accurate values for key rate coefficients and by accounting for the removal of PAH by soot. A directed effort is being made to reduce the computational demands, which at present limit the applicability of the model to simple wellstirred and plug-flow systems.

Rationale:

Polycyclic aromatic compounds are major contributors to air pollution from combustion sources. Basic understanding of the factors that government the detailed chemical composition of the effluents from combustion systems is necessary for the identification of signatures for source attribution and the development of control strategies. The mechanistic and kinetic model developed in this project provides basic understanding of PAH generation in combustion, but the model has only been applied to simplest flow systems. The predictive capability of the model is being improved, so as to extend the use of the model to more complicated systems of practical concern.

Supplemental Keywords:

modeling, air pollution, predict., RFA, Scientific Discipline, Air, Waste, particulate matter, Environmental Chemistry, Atmospheric Sciences, Incineration/Combustion, ambient aerosol, emission control strategies, gas-phase transformation, air pollution, emission controls, PAH, atmospheric transport, combustion, hydrocarbons, aerosol dynamics, kinetc models, aerosols, ambient pollution control, soot profiles, soot

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  • Main Center Abstract and Reports:

    R824970    EERC - Center for Airborne Organics (MIT)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R824970C001 Chemical Kinetic Modeling of Formation of Products of Incomplete Combustion from Spark-ignition Engines
    R824970C002 Combustion Chamber Deposit Effects on Engine Hydrocarbon Emissions
    R824970C003 Atmospheric Transformation of Volatile Organic Compounds: Gas-Phase Photooxidation and Gas-to-Particle Conversion
    R824970C004 Mathematical Models of the Transport and Fate of Airborne Organics
    R824970C005 Elementary Reaction Mechanism and Pathways for Atmospheric Reactions of Aromatics - Benzene and Toluene
    R824970C006 Simultaneous Removal of Soot and NOx from the Exhaust of Diesel Powered Vehicles
    R824970C007 Modeling Gas-Phase Chemistry and Heterogeneous Reaction of Polycyclic Aromatic Compounds
    R824970C008 Fundamental Study on High Temperature Chemistry of Oxygenated Hydrocarbons as Alternate Motor Fuels and Additives
    R824970C009 Markers for Emissions from Combustion Sources
    R824970C010 Experimental Investigation of the Evolution of the Size and Composition Distribution of Atmospheric Organic Aerosols
    R824970C011 Microengineered Mass Spectrometer for in-situ Measurement of Airborne Contaminants