Bio-char

The disadvantages of using mineral acids such as concentrated HCl or H2SO4 to hydrolyse biomass is that they are toxic, corrosive, hazardous and difficult to recycle. The use of heterogeneous solid acids can ease product separation and provide better catalyst recyclability. For example, mesoporous transition metal oxides have been used in biomass transformations. " Polymer-based acids have been employed for the hydrolysis of various organic substrates. " In particular, carbon-based solid acids made by sulfonation of carbonized polymers, such as the solid acid shown in Figure 7.7, have shown promise. Sulfonated bio-char has been similarly used. ... 

Lehmann, J., Gaunt, J., Rondon, M. (2006). Bio-char sequestration in terrestrial ecosystems - a review. Mitigation and Adaptive Strategies for Global Change, 11, 403 27. 

Aburas, H., Demirbas, A., 2015. Evaluation of beech for production of bio-char, bio-oil and gaseous materials. Process Safety and Environmental Protection 94,29-36. 

Azargohar, R., et al., 2014. Effects of temperature on the physicochemical characteristics of fast pyrolysis bio-chars derived from Canadian waste biomass. Fuel 125 (0), 90—100. 

Mohan, D., et al., 2011. Modeling and evaluation of chromium remediation from water using low cost bio-char, a green adsorbent. Journal of Hazardous Materials 188 (1), 319—333. 

Demirbas, A., 2004. Effects of temperature and particle size on bio-char yield from pyrolysis of agricultural residues. Journal of Analytical and Applied Pyrolysis 72 (2), 243—248. http // dx.doi.org/10.1016/j.jaap.2004.07.003. 

Pyrolysis is the decomposition of organic material due to the influence of heat. By performing controlled pyrolysis the woody biomass can be converted into high value added products, namely bio oil, formed in addition to char and gases. 

Fast pyrolysis is a high temperature, fast heating process in which vapor is produced, that is, subsequently condensed as a dark brownish liquid, bio-oil, with some coproduction from char and permanent gases. High yields of pyrolysis vapors/bio-oil can be achieved... 

The Biolig process of the research center Karlsruhe FZK, Germany. Here, flash pyrolysis, with emphasis on straw as feedstock, is tested to produce a bio-oil-char slurry. The pyrolysis reactor compares to the ER reactor (Lurgi-Ruhrgas) by which sand as heat carrier is mixed and transported together with biomass in a double (twin) screw feeder. A novel unit is constructed with a biomass processing capacity of 12 t/day. 

Henrich, E. Raffelt, K. Stahl, R. Weirich, F., Clean syngas from bio-oil/char-slurries. In Science in Thermal and Chemical Biomass Conversion, Bridgwater, A. V. Boocock, D. G. B., Eds., CPL press, Victoria, 2004, pp. 1565-1579. 

The wood pyrolysis is attractive because forest and industrial wood residues can be readily converted into liqtrid products. These liqtrids, as erode bio-oil or slurry of charcoal of water or oil, have advantages in transport, storage, combustion, retrofitting and flexibility in production and marketing (Demirbas, 2007). In the first step of pyrolysis of carbohydrates dehydration occtrrs and at low temperatures dehydration predominates. Dehydration is also known as a char-forming reaction. Between 550 and 675 K volatile products, tar, and char are formed. The volatile products are CO, CO, H O, acetals, furfural, aldehydes and ketones. Levoglucosan is the principle component in tar. 

We successfully demonstrated that hydrogen could be efficiently produced by catalytic steam reforming of carbohydrate-derived bio-oil fractions in a fluidized bed reactor using a commercial nickel-based catalyst. Greater steam excess than that used for natural gas reforming was necessary to minimize the formation of char and coke (or to gasify these carbonaceous solids) resulting from thermal decomposition of complex carbohydrate-derived compounds. 

Pyrolysis is the thermal degradation of an organic material in the absence of oxygen, also the initial step in combustion and gasification. The products formed in the pyrolysis are a solid residue called char, a liquid called bio-oil, and uncondensed gases. The process can be optimized for maximal bio-oil production. Important requirements in this optimization are the following ... 

A typical fluidized-bed reactor system consists of biomass preparation (i.e. drying and grinding), a biomass feeding system, a fluidized-bed pyrolyzer, a char removal system, and a cooling system for bio-oil collection. Char removal from the pyrolysis reactor is beneficial since the char can catalyze vapor cracking, thereby decreasing the bio-oil yield [11],... 

Yields of the different pyrolysis products (i.e. char, bio-oil, and gases) are dependent on the chemical composition of biomass. Biomass with high lignin content produces more char compared to biomass with lower content [20], Furthermore, biomass with high alkali and alkali earth metal concentrations generates less bio-oil and instead more char and gases [14, 15, 21]. Prior to pyrolysis, it is beneficial to dry the biomass to less than 10 wt% moisture in order to minimize the water content in the bio-oil [14],... 

The main product, bio-oil, is obtained in yields of up to 75 percent wt on dry feed basis, together with byproduct char and gas, which are used within the process, so there are no waste streams. Several reviews on fast pyrolysis have been published in recent years that cover, the production, utilization, storage, and upgrading of biomass pyrolysis... 

Tanaka-Kagawa T, Jinno H, Hasegawa T, Makino Y, Seko Y, Haui-oka N, Arrdo M (2003) Functional char acterizadorr of two variant human GSTO 1-ls (Ala 140Asp and Tln 217Asn). Biochem Bio-phys Res Commurr 301 516-520. 

Figure 2 shows a conceptual schematic of fast pyrolysis process that includes the necessary steps of drying the feed to typically less than 10% water to minimise the water in the product liquid oil (although up to 15% can be acceptable), grinding the feed (to around 2 mm in the case of fluid bed reactors) to give sufficiently small particles to ensure rapid reaction, pyrolysis reaction, separation of solids (char), and collection of liquid product (bio-oil). 

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