Investigation of combined catalyst and oxygen carrier systems for the partial oxidation of naphthalene as model tar from biomass gasification

In this paper, catalytic partial oxidation is applied as a thermo-chemical method to remove tar (here: naphthalene as a model component for tar) from Syngas and convert it into fuel gas by using a combined catalyst and oxygen carrier system. In 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. Based on the results of laboratory tests, the perovskite material CSFM (Ca0.5Sr0.5Fe0.5Mn0.5O3-δ) and ilmenite exhibited promising properties as oxygen carriers. They can supply a sufficient amount of oxygen for the oxidation of tar and show excellent redox properties for the regeneration. As a potential catalyst material, NiO showed high catalytic activity. During testing, the combined system of these two materials 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 sorbent was used. In combination with the combined catalyst and oxygen carrier system, the use of H2S sorbent further enhanced the performance of the catalyst. In conclusion, the suitable oxygen carrier materials, catalyst and sour gas sorbent could be identified, which in combination enable the proposed tar removal process.