in Wiley Online Library (wileyonlinelibrary.com) Catalytic fast pyrolysis of cellulose was studied at 500 C using a ZSM-5 catalyst in a bubbling fluidized bed reactor constructed from a 4.92-cm ID pipe. Inert gas was fed from below through the distributor plate and from above through a vertical feed tube along with cellulose. Flowing 34% of the total fluidization gas through the feed tube led to the optimal mixing of the pyrolysis vapors into the catalyst bed, which experimentally corresponded to 29.5% carbon aromatic yield. Aromatic yield reached a maximum of 31.6% carbon with increasing gas residence time by changing the catalyst bed height. Increasing the hole-spacing in the distributor plate was shown to have negligible effect on average bubble diameter and hence did not change the product distribution. Aromatic yields of up to 39.5% carbon were obtained when all studied parameters were optimized.

The effect of steam for the catalytic fast pyrolysis of cellulose with ZSM-5 was studied in a bubbling fluidized bed reactor. Irreversible and reversible changes due to steaming were identified. Steam caused dealumination, a loss of total acidity, an increase in the zeolite-crystal size, and agglomeration of particles. For runs both with and without steam co-feeding, these irreversible changes caused lower yields for aromatics and char/coke, and higher yields for methane and unidentified products. In addition to irreversible catalyst changes, steam co-feeding was also found to reversibly lower yields of aromatics, char/coke, and identifiable oxygenate species, increase yields of CO and methane, and not change the overall yields of CO 2 and olefins.

This paper discusses the impact of catalyst contact time on the catalytic fast pyrolysis yield.