Fast pyrolysis, biomass feedstocks

This pretreatment enhances the energy density of wood by increasing its carbon content and net caloric value and is therefore expected to become more important in the future, especially as a treatment preceding gasification (feedstock moisture content should be <20-30%).Torrefied material is more brittle than the feedstock wood material and it has intermediate characteristics between coal and the feedstock. In case of fast pyrolysis, biomass should normally be dried to about 10% moisture content, since a considerable amount of reaction water is also formed (about 25% of feedstock) during this process. 

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. 

Pyrolysis dates back to at least ancient Egyptian times, when tar for caulking boats and certain embalming agents were made by pyrolysis. In the 1980s, researchers found that the pyrolysis liquid yield could be increased using fast pyrolysis where a biomass feedstock is heated at a rapid rate and the vapors produced also condensed rapidly (Mohan et al., 2006). 

Fast pyrolysis utilizes biomass to produce a product that is used both as an energy source and a feedstock for chemical production. Considerable efforts have been made to convert wood biomass to hquid fuels and chemicals since the oil cri-... 

Thermal conversion involves the use of elevated temperature with or without the presence of oxygen to break down the structure of the feedstock. It includes torrefac-tion, pyrolysis, gasification, and combustion. Thermal conversion of biomass can also be carried out in a solvent (e.g. as in hydrothermal processing) [1], but in this chapter, only torrefaction fast pyrolysis gasification with air, oxygen, or steam and combustion in air will be considered. 

Akzo Nobel is an important producer of chlorine, vinyl chloride and PVC, strongly interested in a process for feedstock recycling of MPW containing PVC. Since 1994 they have chosen a fast pyrolysis process in a circulating fluidized-bed reactor, based on the technique developed by the Battelle Memorial Institute (CO, USA) for biomass gasification. 

Agblevor, F.A., S. Besler, and A.E. Wiselogel (1995) Fast Pyrolysis of Stored Biomass Feedstocks, Energy and Fuels, 9, 635-640. 

Operation of the biomass fast pyrolysis pilot plant with DC-III and woody feedstocks, specifically mixed softwoods (mainly pine) and hardwoods, revealed the following ... 

Fast pyrolysis is a technology by which biomass is decomposed into bio-oil, char and gas. When wood is used as a feedstock, bio-oil is the major product (70 wt.%) The gaseous by-product (15 wt.%) can be fired in a boiler or in a gas engine. Finally, the char (15 wt.%) may be combusted in the pyrolysis unit to drive the process auto-thermally. Only the ash (up to 1 wt.%) is left as a waste stream. 

ITie first step on the way to the decision if fast pyrolysis is a suitable technique for biomass waste exploitation is to take a serious look at the mass balance. In almost every case bio-oil is the pyrolysis product with the highest commercial value no matter weather it is used as bio-fuel for power and heat production or as chemical feedstock. 

Biomass derived fast pyrolysis liquid is now being actively produced for research, testing and evaluation purposes, for use as a chemical feedstock and/or as an alternative fuel for use in boilers, engines and turbines. 

To conclude, bio-oU, the hquid product formed from fast pyrolysis of biomass, can be considered as one of the most promising renewable feedstocks for hydrogen or syngas production. Nevertheless, deactivation of catalysts often occurs during SR of biooil (Zhang et al., 2014), and the use of H2-selective membranes even increases this problem as the hydrogen is removed from the reaction side. 

K.L. Kenney K.G. Cafferty J.J. Jacobson I.J. Bonner G.L. Gresham J. Richard Hess W.A. Smith D.N. Thompson V.S. Thompson J. Shankar Tumuluru N. Yancey. Feedstock supply system design and economics for conversion of hgnoceUulosic biomass to hydrocarbon fuels conversion pathway fast pyrolysis and hydrotreating bio-oU pathway The 2017 design case . Report Number INL/EXT-14-31211. US Department of Energy. Idaho National Laboratory Research. 

As can be seen from Figure 8.6, fast pyrolysis is the primary technology to convert lignocellulosic biomass into biooil, char, and gas. The biooil is feedstock for a subsequent biorefinery approach that aims to further process the biooil into a spectrum of value-added products. This elegant concept is further schematically presented in Figure 8.7. 

Biomass and Biochemical Processes. Phenolic resins have been produced from biomass and using biochemical processes in various ways. In Japan biomass from wood waste or waste from the food industry is treated with phenols and strong acid catalysis and heat to produce phenolic resins (88). Research at the National Renewable Energy Laboratory has shown that ablative fast pyrolysis can be used to convert a wide variety of biomass feedstocks into a liquid oil. The phenolic rich component can be extracted from this oil and used as a low cost replacement for synthetic phenol in phenolic resins (89). In another approach, soybean peroxidase enzymes have been used to prepare resins from phenolic moieties without the use of formaldehyde (90). 

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