State-of-the-Art Char Production with a Focus on Bark Feedstocks: Processes, Design, and Applications

Abstract

In recent years, there has been a surge of interest in char production from lignocellulosic biomass due to the fact of char’s interesting technological properties. Global char production in 2019 reached 53.6 million tons. Barks are among the most important and understudied lignocellulosic feedstocks that have a large potential for exploitation, given bark global production which is estimated to be as high as 400 million cubic meters per year. Chars can be produced from barks; however, in order to obtain the desired char yields and for simulation of the pyrolysis process, it is important to understand the differences between barks and woods and other lignocellulosic materials in addition to selecting a proper thermochemical method for bark-based char production. In this state-of-the-art review, after analyzing the main char production methods, barks were characterized for their chemical composition and compared with other important lignocellulosic materials. Following these steps, previous bark-based char production studies were analyzed, and different barks and process types were evaluated for the first time to guide future char production process designs based on bark feedstock. The dry and wet pyrolysis and gasification results of barks revealed that application of different particle sizes, heating rates, and solid residence times resulted in highly variable char yields between the temperature range of 220 °C and 600 °C. Bark-based char production should be primarily performed via a slow pyrolysis route, considering the superior surface properties of slow pyrolysis chars.

Co-pyrolysis of waste tyre and pine bark: Study of reaction kinetics and mechanisms

“…Interest in co-pyrolysis of waste tyre and biomass has arisen due to the high availability of such polymeric material in waste streams; especially in developing countries. In general, barks have high global production rate of nearly 400 million cubic meters in a year [44]. Despite the high ash content and low energy density of pine bark, the ash is potentially high in inorganic fractions especially Calcium, Magnesium and Sodium [44].…”

“…In general, barks have high global production rate of nearly 400 million cubic meters in a year [44]. Despite the high ash content and low energy density of pine bark, the ash is potentially high in inorganic fractions especially Calcium, Magnesium and Sodium [44]. These inorganic alkali and alkaline earth metals are known to pose catalytic effect during thermochemical process [19,45].…”

The Potential of Waste Phloem Fraction of Quercus cerris Bark in Biochar Production

“…Predictive slagging/fouling indices were calculated using the mineral oxide percentages of the phloem char ash including Fe 2 O 3 , CaO, MgO, Na 2 O, K 2 O, SiO 2 , Al 2 O 3 , and TiO 2 [23,24]. Base-to-acid index (B/A) was calculated using Equation (5).…”

“…Biochars are charcoals produced from biomass via pyrolysis, mostly by slow pyrolysis which is possibly the simplest thermochemical process since it does not require advanced reactors and product separation devices, and produces biochars at low cost and high yield [5]. Biochars are interesting porous solid materials that find applications in different fields such as in soil amendment, in the production of electrode materials, and in the production of activated carbons [6][7][8].…”