Identifying combustion intermediates in premixed MTBE/gasoline/oxygen flame probed via synchrotron radiation

Abstract

America have forbidden the use of MTBE as gasoline additive. Therefore, it is imperative that an environmental friendly fuel or additive be found. To develop a green antiknock agent, the mechanism of MTBE in gasoline must be understood theoretically as the reference to search for new additives.As is known, gasoline itself contains more than 200 kinds of hydrocarbon molecules such as alkane, arene, alkene, etc.[1]. The characteristics and proportion of each kind of hydrocarbon composition influence the properties and combustion performance of gasoline. After adding MTBE, the coupling effect of MTBE and other hydrocarbon composition in gasoline will have an impact on the dynamic and economic performance of fuel. To understand the transformation of MTBE and gasoline in flames as well as the effect on combustion, the interaction between molecules should be studied microscopically from the combustion kinetics' point of view. At present, the measurement methods of molecule concentration and other parameters in combustion kinetics are in situ optical spectroscopic probes and the extractive sampling method. Because the former cannot quantitatively measure large molecules such as polyatomic molecules, large free radicals and polycyclic aromatic hydrocarbons, it has some limitations in the research of the reaction mechanism in the flames of fuel that is composed of a polycomponent and other more complex com positions while burning. The capillary extractive sampling method, which is one of the extractive sampling methods, cannot guarantee the accuracy, because active substances in the reaction will vary with the change of the environment. Therefore, it cannot really probe into the mechanism of gasoline combustion. Fortunately, the tunable synchrotron radiation photoionization technique combined with molecular-beam sampling mass spectrometry provides a powerful tool with obvious advantages for studies of combustion [2]. It can effectively cool molecules and free radicals in flame by using molecular-beam sampling because molecules have no impact on each other after being extracted. In this way, the formation and transformation regulation of active substances Abstract Molecular-beam sampling mass spectrometry (MBMS) combined with tunable synchrotron radiation photoionization technique offers obvious advantages for the study of flame chemistry over other techniques because of the precision measurement of the combustion intermediates and products in flame. In this paper, the results to identify combustion intermediates in low-pressure premixed gasoline/ oxygen flame with the synchrotron radiation were reported. Based on the results obtained, the formation process of five products and the difference between gasoline/oxygen and MTBE/gasoline/oxygen flame were emphatically analyzed. The results achieved provide data basis for the analysis of intermediates and radicals in flame, and are helpful to establish the kinetic modeling of gasoline/oxygen and MTBE/ gasoline/oxygen flames.