Fast pyrolysis and catalytic

Chomet, E. 2001. Biomass to hydrogen via fast pyrolysis and catalytic steam reforming. Proceedings of the 2001 USA. DOE Hydrogen Program Review (NREL/CP 570-30535). 

Elliott, D.C., Wang, H., French, R., Deutch, S., lisa, K., 2014. Hydrocarbon liquid production from biomass via hot-vapor filtered fast pyrolysis and catalytic hydroprocessing of the biooil. Energy Fuels 28, 5909—5917. 

The present chapter discusses aspects, known by the authors, of (a) biomass as feedstock, (b) the concept of bio-refinery, (c) thermochemical routes from lignocellulosic biomass to fuels, and (d) the contribution of catalytic technology. The main focus will be on the catalytic conversion of fast pyrolysis oil into fuels with regard to problems encountered currently and the challenges for future research and development. 

Fast pyrolysis oil has almost the same elemental composition as the biomass itself hence it can be seen as a kind of liquid wood. It can be transported, can be pressurized and processed more easily than solid biomass. One of the major difficulties in the catalytic conversion of solid biomass is achieving effident con-tad between the heterogeneous catalyst (which is most of the times a solid) and the biomass itself. In this context, bio-oil provides more options for easier catalytic conversion. However, pyrolysis is a very complex and the oil is a difficult to handle chemical mixture. Complete vaporization, for instance, is not possible because part of the components start to decompose and polymerize upon heating... 

There are numerous refeieitces that include chemical analyses of fast pyrolysis liquids from a variety of sources, including slow pyrolysis tar, fast pyrolysis liquid and fractions thereof. As fast pyrolysis liquid may be raw, treated, filtered, catalytically derived, upgraded and dependent on the process parameters, a "worst case" must be taken for the liquid compositioii, i.e. high variability. As noted, fast pyrolysis liquid falls within Class 3, based on its physical properties, however, this is further complicated by the presence of other chemicals that are in Class 6.1 - Toxic substances [phenols, etc.] which ate in concentrations above 0.1 wt%. A typical analysis of several fast pyrolysis liquids from different laboratories is given in Table 2. 

The goal of the present study was to investigate the effect of structural peculiarities of different types of cellulose on levoglucosenone formation under catalytic fast pyrolysis conditions. Moreover, amount of phosphoric acid and pretreatment temperature should be determined to provide maximum possible yields of levoglucosenone. 

Wang, D. Czemik, S., and Chomet, E. (1998) Production of hydrogen from biomass by catalytic steam reforming of fast pyrolysis oils. Energy Fuels, 12, 19-24. 

Fast pyrolysis is a process with no need of oxygen that converts biomass into a mixture of low-molecular weight oxygenates to be subsequently cracked and steam reformed. A hydrogen yield of 80 % of the theoretical maximum has been obtained in experimental studies. The marketing of the byproducts seems possible. Focus of research is being laid upon the catalytic reforming step to minimize carbon formation on the catalyst [19, 67]. 

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. 

Catalytic fast pyrolysis Re-USY, H-ZSM-5, P-zeolite Catalyst ensures further cracking of the pyrolysis intermediates and oxygen removal, resulting in the formation of hydrocarbons [61]... 

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