Catalytic fast pyrolysis gases

Cheng Y-T, Jae J, Shi J, Fan W, Huber GW (2012) Production of renewable aromatic compounds by catalytic fast pyrolysis of lignocellulosic biomass with bifiinctional Ga/ZSM-5 catalysts. Angew Chem Int Ed 51(6) 1387-1390... 

Carlson TR, Tompsett GA, Conner WC, Huber GW. Aromatic production from catalytic fast pyrolysis of biomass-derived feedstocks. Top Catal 2009 52 241-52. 

Carlson TR, Jae J, Lin Y-C, Tompsett GA, Huber GW. Catalytic fast pyrolysis of glucose with HZSM-5 the combined homogeneous and heterogeneous reactions. J Catal 2010 270 110-24. 

Other types of biomass pyrolysis oil produced under less specified conditions, typically longer residence time or lower temperature, will have a different chemical composition and will therefore have different chemical and physical properties. Such Uquids will also be produced in lower yields in conjunction with higher gas and solid byproducts. The hydroprocessing described in this chapter has been developed to address the properties of fast pyrolysis bio-oil. A more detailed discussion of fast pyrolysis can be found in chapter Catalytic fast pyrolysis for improved liquid quality . 

During the last six years a fluidized bed fast pyrolysis process for biomass has been developed at the University of Waterloo (The Waterloo Fast Pyrolysis Process). This process gives yields of up to 70% of organic liquids from hardwoods or softwoods, which are the highest yet reported for a non-catalytic pyrolytic conversion process. A fluidized sand bed is used as a reactor and optimum liquid yields are normally obtained in the range of 450 to 550 C at about 0.5 seconds gas residence time with particles of about 1.5 mm diameter or smaller. Two units are in use, one with a throughput of 20 to 100 gms/hr, and another with a throughput of 1 to 4 kg/hr. 

A high aromatics selectivity, however, requires proper catalyst selection. Zhang et al. studied the fast pyrolysis of corncob in absence and presence of a catalyst (ie, ZSM-5) [287]. The presence of the catalyst increased the yields of noncondensable gas, water, and coke, while decreasing the liquid and char yields. The catalyst induced a decrease of the oxygen content of the liquid fraction by more than 25%. These studies indicate the importance of a catalyst during biomass pyrolysis. The most important catalytic parameters affecting the product distribution are pore structure and acid site type. This was demonstrated by testing siUcalite, a material with the same pore structure as ZSM-5 but with intrinsic different acid sites, and siUca-alumina, an amorphous material with Brpnsted acid sites, in the catalytic pyrolysis of... 

Alternative pathways, also discussed in part in the various chapters, include (catalytic) pyrolysis, flash or fast processes for wet biomass without pre-drying, hydro-thermal upgrading (HTU), conversion of solid biomass more or less directly into a natural-gas equivalent called substitute natural gas (SNG), or even to hydrogen. 

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