Short vapour residence time catalytic pyrolysis of spruce sawdust in a bubbling fluidized-bed reactor with HZSM-5 catalysts

Catalytic pyrolysis of spruce sawdust was carried out in a bubbling fluidized-bed reactor using HZSM-5 catalysts. The effects of space velocity, catalyst deactivation, catalyst acidity and catalyst regeneration were studied. The use of catalysts decreased the yield of organic liquids compared to non-catalytic yields while the yields of pyrolytic water and gases increased. Decreasing the space velocity enhanced these effects. The rate of catalyst deactivation depended on the acidity of the catalyst, with more acidic catalysts deactivating more rapidly. Using a catalyst with a Si/Al ratio of 140 resulted in the largest changes in bio-oil properties. Periodic regeneration of the catalyst in the fluidized-bed reactor was also demonstrated using varying regeneration times and temperatures. It was shown that compared to BFB reactors, CFB reactor types would offer better operating characteristics for commercial scale catalytic pyrolysis processes in regard to vapour residence times, and catalyst activity and regeneration.