Interaction of Surface and Gas Reactions in High Temperature (max ca. 1300°C) High Pressure (max. ca. 5 M Pa) Catalytic Alkane Oxidations

点击翻译按钮获取中文摘要

The transformation of natural gas components like methane and ethane into valuable chemicals like methanol, formaldehyde or ethylene is a big challenge for catalysis research and chemical engineering in the 21st century. Heterogeneous catalytic alkane oxidations at high temperatures and pressures might be a way to accomplish these transformations on a large scale provided that it is possible to control the interaction between reactions at the catalyst surface and in the surrounding gas phase and to maximize the kinetically controlled formation of partial oxidation products. By employing novel in-situ diagnostic techniques to investigate surface and gas chemistry under reaction temperatures up to 1300 °C and pressures up to 5 M Pa, this project will contribute to a mechanistic understanding of chemical and physical surface gas interactions in catalytic alkane oxidations under conditions, largely unexplored by experimental researchers before. To compare nature and importance of coupled surface - gas reactions on different catalytic materials, a metallic catalyst (Pt), a strong basic coupling catalyst (Li/MgO) and a redox catalyst (V Ox) will be investigated. Gas species, surface and gas temperature profiles without and with isotope labelling will be measured with µm spatial and ms time resolution using a newly developed capillary technique with MS or GC species analysis. Gas phase radicals will be studied by molecular beam mass spectrometry. Both techniques have been developed in preparation for this project. Spatially resolved Raman spectroscopy with a fiber probe will be applied to study the catalyst, gas species, adsorbed species and coke deposits. Confocal Raman microscopy will be used to map the catalyst-gas boundary layer to explore mass and heat transport. Numerical simulations will be performed to compare state-of-the-art microkinetic surface and gas models against the experimental data and to reveal selectivity determining rate parameters. If possible, improvements will be made. The knowledge derived by combining in-situ experiments and numerical simulations will be used to tailor catalyst, reactor and reaction conditions for optimum yields of partial oxidation products. A knowledge based control of the kinetics of high temperature high pressure catalytic alkane oxidations could push the yields of partial oxidation products into regions of economic interest and could enhance the use of natural gas as chemical feedstock in addition to its use as a clean fuel.