Catalytic pyrolysis of soda lignin over zeolites using pyrolysis gas chromatography-mass spectrometry

Catalytic fast pyrolysis of soda lignin was examined at different temperatures (500,600,700,800 and 900 °C) in the presence of three zeolites with different Si/Al ratio using the Py-GC/MS in order to investigate best catalytic system. The three zeolites are y-zeolite (8-9), mordenite (15-17), ZSM-5 (30-40), which have static pore sizes 0.74, 0.65, and 0.59 nm respectively. The shape and acidity of zeolites, as well as pyrolysis temperature, have a significant effect on product distribution in catalytic fast pyrolysis. Y-zeolite was the most effective catalytic system among all catalysts for deomethoxylation and dehydroxylation of small oxygenates as well as bulky oxygenates to produce aromatics. However, mordenite and ZSM-5 could not convert the large oxygenates due to size exclusion and pore blockage. Highest yield of aromatics with significant amount of aromatic dimers was obtained over y-zeolite and then yield of aromatics followed in order by mordenite and ZSM-5 at 800 °C.