a b s t r a c tAn international study of fast pyrolysis of lignin was undertaken. Fourteen laboratories in eight different countries contributed. Two lignin samples were distributed to the laboratories for analysis and bench-scale process testing in fast pyrolysis. Analyses included proximate and ultimate analysis, thermogravimetric analysis, and analytical pyrolysis. The bench-scale test included bubbling fluidized-bed reactors and entrained-flow systems. Based on the results of the various analyses and tests it was concluded that a concentrated lignin (estimated at about 50% lignin and 50% cellulose) behaved like a typical biomass, producing a slightly reduced amount of a fairly typical bio-oil, while a purified lignin material was difficult to process in the fast pyrolysis reactors and produced a much lower amount of a different kind of bio-oil. It was concluded that for highly concentrated lignin feedstocks new reactor designs will be required other than the typical fluidized-bed fast pyrolysis systems.

The temperature dependence of the pyrolysis products of two types of lignin (Alcell lignin and Asian lignin) was investigated using pyrolysis−gas chromatography−mass spectrometry (PyGC−MS). About 50 compounds were identified and quantified for each type of lignin over a temperature range of 400−800 °C. The maximum yield of phenolic compounds was obtained at 600 °C for both lignins, which was 17.2% for Alcell lignin and 15.5% for Asian lignin. Most of the phenolic compounds had an individual yield of less than 1%; however, for Alcell lignin, 5-hydroxyvanillin was the highest yield at 4.29 wt % on dry ash-free lignin, and for Asian lignin, 2-methoxy-4-vinylphenol was the highest yield at 4.15 wt % on dry ash-free lignin.

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