Abstract
Fuels are continuing to be derived from fossil sources, but as production technology improves, biofuels and synthetic fuels are expected to emerge as scalable long-term sources of liquid fuels. Efforts are being made to ensure that this next-generation of fuels is cleaner burning than the last. In order to inform the production and processing of cleaner burning fuels, more needs to be known about how molecular structure influences the formation of pollutant emissions. Reducing airborne quantities of particulate matter (PM) is of particular interest for human health and the environment. This publication presents a 13C labelling technique, which has been developed and applied to identify the influence of local molecular structure on the formation of PM. The paper applied the technique based on the 13C stable isotope to trace the conversion of individual carbon atoms to PM in the case of several oxygenated and hydrocarbon molecules. A laminar tube reactor facility has been used for generating and collecting samples of PM under pyrolysis conditions. A number of single-component oxygenated and hydrocarbons (ethanol, propanol, pentanol, cyclopentanol, ethyl acetate, and toluene) have been enriched with 13C at specific carbon atom locations and the 13C/12C isotope ratios of PM were measured. The contribution to PM of particular carbon atoms within a molecule was evaluated, and the results shed new light of how individual carbon atoms in a molecule convert to PM. It was found that the conversion to PM of different atoms within a molecule varies widely, depending on the identity of their neighbouring moiety. Furthermore, it was shown that oxygen-containing functional groups have a significant influence on the formation of particulates, partly through a reduction in the conversion to PM of carbon atoms, which are adjacent to oxygen atoms.
Highlights
Combustion generated emissions, such as NOx, and particulate matter (PM), have long been identified as being detrimental to human health
In the case of ethanol, it is clearly seen that the OH carbon, shown as ‘‘a’’ in Fig. 3, contributes much less to the overall mass of PM compared to the methyl-carbon (b), calculated to be approximately 27% and 68% respectively
The result from ethanol showed that 68% of PM from ethanol arose from the methyl-position, and a similar result was found by an earlier study of PM formed from ethanol in a Bunsen flame, using a 14C radiotracer technique, were a carbon conversion ratio of 2:1, methyl-to-hydroxyl carbon, was reported [18]
Summary
Combustion generated emissions, such as NOx, and particulate matter (PM), have long been identified as being detrimental to human health. Following a recent review by the World Health Organisation, PM has been identified as a group 1 carcinogenic agent, satisfying sufficient evidence of carcinogenicity in humans [2]. The importance of reducing airborne quantities of PM has come to the forefront for its prospect of reaping immediate climatic benefits. There has been suggestion that, unlike CO2, the precipitation of PM over a timescale of weeks means that the average PM concentration in the atmosphere can be reduced more rapidly than that of CO2, by taking measures that lower the emission of PM in the atmosphere [3,4]. Stringent legislation over the past 20 years restricts the emission
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
