The Complexity of Lignin Thermal Degradation in the Isothermal Context

Abstract

Thermal degradation of lignin in nitrogen atmosphere is evaluated by linear heating and isothermal tests. While linear heating suggests that thermal decomposition in the 200–400 °C range mainly consists of a single step, a careful analysis of isothermal tests points to different lignin fractions having different stabilities. This is an important point for practical predictions, since kinetics obtained as if the degradations at different temperatures were the same would lack practical utility. Instead, stairway type tests are proposed to evaluate the degradation rates and sample quantities involved at the temperatures of interest.

Revealing the Potential of Waste Fibers from Timber Production and Clearings for the Development of Local Bio-based Insulation Fiberboards in French Guiana

“…The decomposition of lignin is slower and more complex since lignin fractions have different stabilities. This component thus covers a wider range of temperature from 200 °C to 450 °C under nitrogen [21]. In presence of oxygen, the devolatilization peaks appear at lower temperature (-15 °C and -35 °C for hemicelluloses and cellulose, respectively) [22].…”

“…Under these conditions, the combustion is guaranteed to be complete. Heat release rate (HRR) was calculated from the oxygen consumption according to Huggett's relation [21] (1 kg of consumed oxygen corresponds to 13.1 MJ of heat release). Each test was performed twice.…”

Thermal Degradation Kinetics and Lifetime Prediction of Cellulose Biomass Cryogels Reinforced by its Pyrolysis Waste

“…In the case of lignin (250-500 °C), due to its highly complex structure, as it is a heterogeneous polymer, its crosslinking occurs in different ways, this is because lignin is derived from lignol precursors. Due to this, lignin has different stabilities, which directly reflects on its degradation behavior [43][44][45][46][47] . Even starting at low temperatures, the degradation process occurs more slowly, so lignin is the main responsible for the formation of residual material (17.3%) 1,37,43 .…”

Advances in Catalytic Depolymerization of Lignin

“…Eventually biomass is transformed into low molecular weight chemicals and bio‐oil [44] . The small molecule products obtained from the early common pyrolysis had low yields and were prone to coking and carbon accumulation [45] . The pyrolysis reaction mainly produces a large amount of gas.…”