Oxidation of particulate matter by NO2
Tutor / director / evaluatorSkoglundh, Magnus
Document typeMaster thesis (pre-Bologna period)
Rights accessRestricted access - confidentiality agreement
Road transportation is one of the largest contributors to air pollution, large efforts have been made to limit automobile emissions. Most of the pollutants from car emissions come from incomplete combustion of fuel in the engine. This work is focused on particulate matter (PM) which is formed from small graphite structures in the combustion chamber at high pressure. Particulate matter has a lot of negative effects, regarding both health and environment. That’s why specific filters for this kind of pollutant have been developed and commercialized: the so called Diesel Particulate Filters. The challenging step in these filters is the regeneration step which consists on burning the soot that is trapped in the filter. One solution to get rid of this soot is the oxidation by NO2. In order to get a better understanding of the oxidation of particulate matter by NO2, Temperature Programmed Oxidations (TPO) and Isothermal Oxidations needed to be performed with NO2 with O2 in addition or in absence. The experiments were conducted in a gas flow reactor tube using Printex U as a model carbon for PM. After the reactor, different analyzers measured the outlet concentrations of each gas. CO and CO2 concentrations were measured by non‐dispersive infrared analyzers and the NOX measurements were analyzed by a chemiluminescense analyzer. Heat and mass transfer were checked in the reactor and was found that the experimental conditions have to be carefully selected in order to study the kinetics of PM oxidation by NO2. NO2 depletion and NOX equilibrium were studied and taken into account in order to interpret the results accurately. Oxygen has clearly an enhancing effect on oxidation by NO2 which cannot fully be explained by reoxidation of NO. The estimation of activation energy requires isothermal experiments at high NO2 concentrations, where the NO2 depletion could be neglected. The estimated values for activation found are 45 kJ/mol for CO and 70 kJ/mol for CO2. It is seen that the variation of the reaction order with respect to NO2 in a range from 0.5 to 2 have an influence on the activation energyvalues.
SubjectsParticles -- Environmental aspects, Nitrogen oxids, Automobiles -- Motors -- Exhaust gas, Partícules (Matèria) -- Aspectes ambientals, Òxids de nitrògen, Automòbils -- Motors -- Gas d'escapament
ProvenanceAquest document conté originàriament altre material i/o programari no inclòs en aquest lloc web
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