Subcontract Report Investigation of Nitro-Organic NREL/SR-540-45597 Compounds in Diesel Engine June 2010 Exhaust Final Report February 2007 – April 2008 John Dane and Kent J. Voorhees Colorado School of Mines Department of Chemistry and Geochemistry Golden, Colorado Subcontract Report Investigation of Nitro-Organic NREL/SR-540-45597 Compounds in Diesel Engine June 2010 Exhaust Final Report February 2007 – April 2008 John Dane and Kent J. Voorhees Colorado School of Mines Department of Chemistry and Geochemistry Golden, Colorado NREL Technical Monitor: Matthew Ratcliff Prepared under Subcontract No. NEV-7-77395-01 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 • www.nrel.gov NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Operated by the Alliance for Sustainable Energy, LLC Contract No. DE-AC36-08-GO28308 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. 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Box 62 Oak Ridge, TN 37831-0062 phone: 865.576.8401 fax: 865.576.5728 email: mailto:[email protected] Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone: 800.553.6847 fax: 703.605.6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm This publication received minimal editorial review at NREL Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste Acknowledgment Work described in this report is supported by the U.S. Department of Energy (DOE) Vehicle Technologies Program under the Nonpetroleum-Based Fuels task. This task is managed by Kevin Stork at DOE and by Robert McCormick at the National Renewable Energy Laboratory. i Executive Summary Diesel particle filters (DPF) dramatically reduce the level of particulate matter (PM) emitted by diesel engines. There has not, however, been much research to verify that unregulated organic pollutants associated with diesel PM are also reduced by the use of DPFs. The U.S. Department of Energy’s National Renewable Energy Laboratory recently upgraded its ReFUEL engine and vehicle testing facility’s capabilities to speciate unregulated gas-phase emissions. To complement this capability, the laboratory contracted with the Colorado School of Mines to study the effects of soy biodiesel fuel and a DPF on emissions of polycyclic aromatic hydrocarbons (PAH) and nitro-polycyclic aromatic hydrocarbons (NPAH). These are related types of harmful but unregulated emissions associated with PM from diesel engines. In this study, the Colorado School of Mines developed procedures to sample diesel PM emissions from raw and diluted exhaust, with and without a DPF. They also developed improved procedures for extracting PAH and NPAH from the PM and quantifying those compounds with a gas chromatograph-electron monochromator mass spectrometer. While the study found the DPF generally reduced PAH emissions by 1 to 3 orders of magnitude, PAH conversion was lowest in the case of B100, suggesting that PAHs were actually being formed in the DPF. This finding warrants further investigation. Orders of magnitude reductions were also generally found for NPAH emissions exiting the DPF. However, the conversion of 1-nitropyrene through the DPF was less than 50% for all fuels. Because 1-nitropyrene has been shown to be mutagenic and carcinogenic, and because the DPF may concentrate condensable organics on a larger number of smaller particles, this could be a very significant concern. Differences in NPAHs between raw and dilution-tunnel PM samples suggest that chemical reactions continue through the raw exhaust system or occur during dilution. The apparent net effect is to reduce the diversity of NPAH compounds and in particular increase the amount of 1-nitropyrene. ii Acronyms and Abbreviations AVL powertrain engineering and test equipment manufacturer B100 100% biodiesel diesel fuel B20 20% biodiesel diesel fuel Cert certification diesel fuel CSM Colorado School of Mines DCM dichloromethane DNPH dinitrophenyl hydrazine DOC diesel oxidation catalyst DPF diesel particle filter DPF-out exhaust down-stream of installed DPF ECD electron capture detectors EI electron ionization EI− negative ion electron ionization EI+ positive ion electron ionization EM electron monochromator EM-MS electron monochromator mass spectrometry Engine-out exhaust without DPF installed EPA Environmental Protection Agency FAME fatty acid methyl ester GC gas chromatography GC/EM-MS GC-MS instrument including trochoidal EM GC-MS gas chromatograph-mass spectrometry HPLC high-pressure liquid chromatography JEOL EM-MS instrument manufacturer MFC mass flow controller NCI negative-ion chemical ionization NIST National Institute of Science and Technology NPAH nitro-polycyclic aromatic hydrocarbons NREL National Renewable Energy Laboratory PAH polycyclic aromatic hydrocarbons PM particulate matter PTFE polytetrafluoroethylene ReFUEL NREL’s Renewable Fuels and Lubricants Laboratory Rel Int relative intensity SIM selected ion monitoring SPE solid-phase extraction TIC total ion current URG Name of PM filter-holder vendor iii Table of Contents EXECUTIVE SUMMARY ................................................................................................ ii 1. INTRODUCTION .......................................................................................................... 1 2. GC/ELECTRON MONOCHROMATOR-MASS SPECTROMETRY ......................... 3 2.1 Background ............................................................................................................... 3 2.2 Instrumentation ......................................................................................................... 4 3. METHOD DEVELOPMENT ......................................................................................... 5 3.1 Filter Experiments ..................................................................................................... 5 3.2 PM Filter Conditioning and Weighing ..................................................................... 6 3.3 Solvent Purities ......................................................................................................... 9 3.4 PAH and NPAH Standard Studies ............................................................................ 9 3.5 Detection of Ethyl Nitrite ........................................................................................ 14 3.6 Solvent Extraction Studies ...................................................................................... 15 3.7 Solid-Phase Extraction Studies ............................................................................... 17 3.8 Evaporation Procedure ............................................................................................ 19 3.9 Complete Engine-out Sample Preparation Procedure ............................................. 20 3.10 Complete DPF-out Sample Preparation Procedure ............................................... 21 3.11 Engine Testing Procedure ..................................................................................... 21 3.12 Raw Exhaust Sampling ......................................................................................... 22 3.13 Dilute Exhaust Sampling ...................................................................................... 23 4. RESULTS AND DISCUSSIONS ................................................................................. 24 4.1 Raw Exhaust Gravimetric Data .............................................................................. 24 4.2 Results for Engine-out Raw Exhaust ...................................................................... 25 4.3 Results for DPF-out Raw Exhaust .......................................................................... 31 4.4 Dilute Exhaust Gravimetric Analysis ..................................................................... 34 4.5 Results for Engine-out Dilute Exhaust ................................................................... 35 4.6 Results for DPF-out Dilute Exhaust ....................................................................... 41 5. CONCLUSIONS AND FUTURE RESEARCH .......................................................... 46 6. REFERENCES ............................................................................................................. 48 iv 1. Introduction The National Renewable Energy Laboratory (NREL)