Thermochemische Eigenschaften von kombinierten Katalysator- und Sauerstoffträgersystemen für die partielle Oxidation von Teeren aus der Biomassevergasung

摘要

A big, not yet completely solved problem in biomass gasification processes is the high proportion of higher-boiling hydrocarbons (tars) in the fuel gas, which always leads to high equipment and operating costs. Therefore, a high effort has to be made to remove them from the fuel gas. In this thesis, catalytic partial oxidation is applied as a thermo-chemical method to remove tar and convert it into fuel gas by using a combined system of catalyst and oxygen carrier. By this method, the amount of oxygen needed for the partial oxidation of tar will be supplied by an oxygen carrier, which will also serve as a carrier of the catalyst. Several oxygen carrier materials were manufactured and tested for their redox properties by conducting TG measurements. In addition, different catalyst materials were synthesized and analysed by a molecular beam mass spectrometer for their catalytic activities. The influence of trace substances (such as HCl, KCl and H2S) on the performance of the material systems was also tested on laboratory-scale. Based on the results of laboratory tests, CSFM5555 and ilmenite exhibited very promising properties as oxygen carriers. They can supply a sufficient amount of oxygen for the oxidation of tar and show good redox properties for the regeneration. As a potential catalyst material, NiO showed high catalytic activity. During testing, the combination of these two material groups showed high ability for the removal of naphthalene, which was used as a model component for tar. In order to prevent the catalyst (NiO) from being poisoned by H2S, H2S sorbents (CuO) were used. The utilisation of H2S sorbents in combination with the catalyst-oxygen-carrier system enhanced significantly the performance of the catalyst. In conclusion, suitable oxygen carrier materials, catalysts and sour gas sorbents will be identified in this work, which in combination enable the proposed tar removal process.