Tar cracking in low temperature gasifier for biomass, phase 2

The experiments were carried out by batch. The residence time for the released products in the pyrolytic zone was approximately 25 s. The tar generated was subjected to thermal cracking at 800 deg. C with and without partial oxidation at a residence time less than 1 s. The tar was collected in cold traps containing acetone. The tar was defiend as the sum of the light part as determined by gas chromatography - mass spectrometry (GC/MS), the heavy part as determined gravimetrically and the aerosol part collected at filters. Separate experiments were performed to determine water, the quantity of gas and its composition. The heavy part of the tar was characterised by size exclusion chromatography. Furthermore, fractions were collected for characterisation by flash pyrolysis GC/MS. The analysis demonstrated that the high molecular weight fraction contained substructures related to phenol. The addition of deuterium labelled phenol to the virgin tar indicated a delayed incorporation of phenol into more complex compounds. However, no isotope exchange was observed. This excludes simple phenol/aldol condensations leaving only other routes involving the hydroxy group