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Atmospheric reactivity of cyclic ethers of relevance to biofuel combustion

Graham, Emelie LU (2015) In Student thesis series INES NGEM01 20151
Dept of Physical Geography and Ecosystem Science
Abstract
Biofuels are considered to be an environmental friendly alternative to fossil fuels as they have the potential to reduce the global emissions of greenhouse gases. Studies have showed that an increased use of ethanol could alter the atmospheric chemical composition and enhance urban ozone concentrations resulting in higher human mortality rates. In recent years furanic compounds have been considered as second generation biofuels as they can be produced from non-food biomass. This project aims to improve the understanding of the impact of furanic biofuels in the atmosphere. Laboratory studies have been performed in smog chambers at Copenhagen Centre for Atmospheric Research and the University of Oslo, considering the reactions of furan,... (More)
Biofuels are considered to be an environmental friendly alternative to fossil fuels as they have the potential to reduce the global emissions of greenhouse gases. Studies have showed that an increased use of ethanol could alter the atmospheric chemical composition and enhance urban ozone concentrations resulting in higher human mortality rates. In recent years furanic compounds have been considered as second generation biofuels as they can be produced from non-food biomass. This project aims to improve the understanding of the impact of furanic biofuels in the atmosphere. Laboratory studies have been performed in smog chambers at Copenhagen Centre for Atmospheric Research and the University of Oslo, considering the reactions of furan, 2,3-dihydrofuran and 2,5-dihydrofuran with ozone and chlorine radicals. The furanic ozonolysis mechanism was further studied using computational methods.

The results of the relative rate studies show that furan reacts slower with both ozone and Cl than the two DHF do, while the reactions of 2,3-DHF with ozone and Cl is faster than the corresponding reactions of 2,5-DHF. When comparing the results with literature data it was found that furans will mainly decompose due to tropospheric reactions with OH. The furanic Cl reaction may become important, close to local chlorine sources, in highly polluted areas were elevated VOC concentrations result in increased competition for the tropospheric OH reaction. Furthermore it was found that 2,3-DHF react immediately with Cl2, while furan and 2,5-DHF did not.

The results of the product study propose that furanic ozonolysis produces shorter oxygenated organic compounds, such as aldehydes and carboxylic acids. This study shows that furanic biofuels mainly decompose into atmospheric compounds associated with elevated tropospheric ozone levels and urban air pollution. Emission of these compounds to the atmosphere can therefore be expected to result in elevated levels of ground level ozone. (Less)
Popular Abstract (Swedish)
Biobränslen anses vara ett miljövänligt alternativ till fossila bränslen eftersom de har potential att minska de globala utsläppen av växthusgaser. Studier har visat att en ökad användning av etanol kan komma att påverka atmosfärens kemiska sammansättning och på så sätt bidra till förhöjda koncentrationer av marknära ozon, en luftförorening som är känd för att orsaka ökad dödlighet. Furaner kan framställas från bland annat mat- och skogsavfall och har därför introducerats som en andra generationens biobränslen. Detta projekt syftar till att förbättra förståelsen för hur furan-baserade biobränslen kan komma att påverka atmosfären. Laborationer har utförts i gaskammare vid Köpenhamns Universitet och Universitet i Oslo för att studera hur... (More)
Biobränslen anses vara ett miljövänligt alternativ till fossila bränslen eftersom de har potential att minska de globala utsläppen av växthusgaser. Studier har visat att en ökad användning av etanol kan komma att påverka atmosfärens kemiska sammansättning och på så sätt bidra till förhöjda koncentrationer av marknära ozon, en luftförorening som är känd för att orsaka ökad dödlighet. Furaner kan framställas från bland annat mat- och skogsavfall och har därför introducerats som en andra generationens biobränslen. Detta projekt syftar till att förbättra förståelsen för hur furan-baserade biobränslen kan komma att påverka atmosfären. Laborationer har utförts i gaskammare vid Köpenhamns Universitet och Universitet i Oslo för att studera hur furan, 2,3-dihydrofuran och 2,5-dihydrofuran reagerar med ozon och fria klorradikaler. Vidare har den kemiska mekanismen för ozonolys av furaner studerats med hjälp av kemiska beräkningsmetoder.

De experimentella resultaten tyder på att furan reagerar långsammare med ozon och klor än vad de båda DHF gör, 2,3-DHF reagerar dessutom snabbare med ozon och klor än vad 2,5-DHF gör. Resultaten jämfördes med tidigare forskning och det kunde konstateras att furaner huvudsakligen reagerar med OH i troposfären. Däremot kan klorreaktioner komma att bli betydelsefulla nära lokala klorkällor, i kraftigt förorenade områden med ökad konkurrens om OH. Vidare visade studien att 2,3-DHF reagerar omedelbart med Cl2, men att varken furan och 2,5-DHF gör det.

Produktstudien tyder på att ozonolys av furaner producerar korta syreinnehållande kolföreningar, så som aldehyder och karboxylsyror. Denna studie visar att furan-baserade biobränslen huvudsakligen bryts ner till kemiska föreningar som är associerade med luftföroreningar och förhöjda ozonhalter i troposfären. Utsläpp av olika furaner till atmosfären förväntas därför att resultera i förhöjda nivåer av marknära ozon. (Less)
Please use this url to cite or link to this publication:
author
Graham, Emelie LU
supervisor
organization
alternative title
Atmosfärisk reaktivitet av cykliska etrar relevanta för biobränsleförbränning
course
NGEM01 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Ecosystem Science, Physical Geography, 2nd generation biofuels, furans, tropospheric chemistry, ozonolysis, atmospheric kinetics, computational chemistry, IR Spectroscopy, Atmospheric Science & Biochemical Cycles
publication/series
Student thesis series INES
report number
359
funder
Foundation in memory of Fredrik Lindström
funder
Nils Flensburgs travel scholarship fund
funder
Nordplus Higher Education programme
language
English
id
7989478
date added to LUP
2015-09-25 16:26:59
date last changed
2015-09-25 16:26:59
@misc{7989478,
  abstract     = {Biofuels are considered to be an environmental friendly alternative to fossil fuels as they have the potential to reduce the global emissions of greenhouse gases. Studies have showed that an increased use of ethanol could alter the atmospheric chemical composition and enhance urban ozone concentrations resulting in higher human mortality rates. In recent years furanic compounds have been considered as second generation biofuels as they can be produced from non-food biomass. This project aims to improve the understanding of the impact of furanic biofuels in the atmosphere. Laboratory studies have been performed in smog chambers at Copenhagen Centre for Atmospheric Research and the University of Oslo, considering the reactions of furan, 2,3-dihydrofuran and 2,5-dihydrofuran with ozone and chlorine radicals. The furanic ozonolysis mechanism was further studied using computational methods.

The results of the relative rate studies show that furan reacts slower with both ozone and Cl than the two DHF do, while the reactions of 2,3-DHF with ozone and Cl is faster than the corresponding reactions of 2,5-DHF. When comparing the results with literature data it was found that furans will mainly decompose due to tropospheric reactions with OH. The furanic Cl reaction may become important, close to local chlorine sources, in highly polluted areas were elevated VOC concentrations result in increased competition for the tropospheric OH reaction. Furthermore it was found that 2,3-DHF react immediately with Cl2, while furan and 2,5-DHF did not.

The results of the product study propose that furanic ozonolysis produces shorter oxygenated organic compounds, such as aldehydes and carboxylic acids. This study shows that furanic biofuels mainly decompose into atmospheric compounds associated with elevated tropospheric ozone levels and urban air pollution. Emission of these compounds to the atmosphere can therefore be expected to result in elevated levels of ground level ozone.},
  author       = {Graham, Emelie},
  keyword      = {Ecosystem Science,Physical Geography,2nd generation biofuels,furans,tropospheric chemistry,ozonolysis,atmospheric kinetics,computational chemistry,IR Spectroscopy,Atmospheric Science & Biochemical Cycles},
  language     = {eng},
  note         = {Student Paper},
  series       = {Student thesis series INES},
  title        = {Atmospheric reactivity of cyclic ethers of relevance to biofuel combustion},
  year         = {2015},
}