Mass spectrometric investigation of chemical conversion processes in flow reactors

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The main objective of work in the research unit is to investigate the use of engines as flexible chemical reactors. In processes, referred to here as polygeneration, the engines should simultaneously provide higher-value chemicals, heat, and mechanical work. The planned work is the continuation of research performed in the project GV1 of the research unit FOR 1993.GV1 focusses on the investigation of the fundamental kinetic processes underlying the chemical conversion processes. In the third phase of the project, the main objective of the investigations is to assess the influence of ozone as additive on the formation of interesting chemicals because it is expected that ozone already activates the conversion reactions at very low concentrations. Fuel-rich gas mixtures are investigated in two types of flow reactors at temperatures between T = 300 – 1200 K, and high pressure (1 – 20 bar) for different residence times. The gas composition at the outlet of the reactor is analyzed by mass spectrometry and gas chromatography. Desired chemical conversion processes are all reactions that can potentially be used to store chemical energy, e.g. dehydrogenations, steam reforming, or C-C-coupling reactions, and partial oxidations. Conditions that lead to the formation of interesting products are identified by analyzing the product gas composition as function of the process parameters pressure, temperature or the residence time. Concentration profiles as function of reactor temperature or residence time serve as validation data for the development and testing of the “PolyMech” reaction mechanism developed in the research unit 1993. The reaction mechanism serves as a means of information transfer to apply results from the fundamental investigations to the application – the co-production of work and chemicals in the motor.The work in the third phase of the project relies on the methods already successfully implemented in the first two project phases and established collaborations. In the third project phase, biogenic fuels and additives (biogas, ethanol, methanol and oxymethylene ethers) will be used in addition to methane and natural gas to expand the accessible spectrum of products. The most important scientific question is, however, how the use of ozone as additive affects the chemical conversion processes. Ozone decomposes already at low temperature into reactive radicals and can activate the conversion reactions in this way. Since, in contrast to other additives, it does not compete with the fuel for the available oxygen, it does not limit the conversions of the fuel. Based on these observations, it will be investigated to what extent ozone can be used to improve the product yields and the selectivities of oxygenated and non-oxygenated products. As a result of the investigations, a fundamental kinetic understanding of the reaction mechanisms of ozone is generated.