Читать книгу Handbook of Biomass Valorization for Industrial Applications - Группа авторов - Страница 17

Biomass is converted into useful energy after applying various technologies into some valuable products like sugars, lignin, glycerol, etc. Generally, biomass is just decomposed/burned directly to generate energy in industries but in this process, fewer benefits can be achieved. Therefore, some important techniques which valorize the biomass utilization are employed such as pyrolysis, gasification, liquefaction, and biochemical processes [5]. These non-photocatalytic biomass valorization techniques can upgrade the quality and provide variety of products with maximum utilization of biomass feedstocks, if the participation of catalysts is possible.

Table 1.2 Biomass valorization techniques with important aspects [5].

Biomass valorization techniques	Feedstocks	Temperature	Products
Pyrolysis	Cellulose, hemicelluloses, and lignin	500 °C	Charcoal, bio-oil and gaseous fuels
Gasification	Combustible gas mixture	800 °C	Syngas
Liquefaction	Agro-residue and algal biomass	150–420 °C	Liquid fuels such char, fertilizers, biofuels
Biochemical methods	Organic biomass wastes, agricultural wastes	Low temperature	Biogas, bioethanol

Pyrolysis converts wood biomass into solid (charcoal), liquid (bio-oil) and gaseous products by using fast pyrolysis mostly in the absence of oxygen at 500 °C. This technology is used in many industries on a wide scale [6, 7]. Gasification, on the other hand, is used to convert combustible gas mixture by partial oxidation process at high temperature approximately 800 °C. It produces an important fuel as syngas which is used in the production of methanol [8]. Liquefaction is a little different than the previous two techniques because of the conversion of biomass into valuable liquid fuels at low temperature within the range of 150–420 °C and high pressures as 1–240 bars [9, 10]. This valorization technology is more useful to improve yield through homogeneous/heterogeneous catalysts. Pyrolysis, gasification and liquefaction processes are considered as thermo-chemical conversion methods.

The biochemical route consists of anaerobic digestion and fermentation processes at low temperature which converts animal wastes, sewage sludge, agricultural residues into bio fuels such as biogas and bioethanol. It is widely used to treat organic wastes because of its large numbers of benefits such as increasing nutritional recovery of fertilizers [11, 12].

Except these technologies, there many more physico-chemical conversion processes such as Esterification/Transesterfication of vegetable oils, animal fats, and waste oil products which provides glycerol and liquid fuels as products. The obtained products with operating conditions of aforementioned techniques are given in Table 1.2.