Novel Methodology for Lignocellulose Composition, Polymorphism and Crystallinity Analysis Via Deconvolution of Differential Thermogravimetry Data

Thermogravimetric Analysis as a High-Throughput Lignocellulosic Biomass Characterization Method

“…Differential thermogravimetric (DTG) curves are commonly used to locate distinct thermal degradation events. Literature has established the decomposition temperature ranges for hemicellulose, cellulose, and lignin, approximately 250–300, 300–350, and 300–500 °C, for each component, respectively. , Hemicellulose degrades at the lowest temperatures in a broad peak because of its amorphous structure, and cellulose degrades next as a sharp peak due to the polymer’s homogeneity and crystallinity. , Lignin degrades last across a wide temperature range, and its degradation pattern is highly variable between feedstocks largely impacted by the distributions of C–O and C–C bonds between monolignol subunits and differences in S/G/H ratios. , However, these degradation windows overlap, especially in an inert atmosphere, in which most of the previously reported TGA characterization studies are conducted, because they were focused on biomass pyrolysis. − TGA in an oxidative environment (i.e., under air) significantly improves separation between the holocellulose and lignin degradative events, and this improvement in resolution is shown for the hybrid poplar in Figure S1. TGA curves for each of the individual components are shown in Figure S2.…”

“…20 Another limitation of the pyrolysis-based approaches is that additional experiments are required to account for the remaining char content at the end of TGA runs. 27 Other TGA characterization protocols can consistently determine the lignin content in a specific species but have not been generalized to multiple species of diverse LCB feedstocks. 28−30 Furthermore, some TGA approaches require the biomass to be fractionated prior to analysis, disrupting the chemical structure of the components prior to measurement and limiting the potential throughput by including labor-intensive steps.…”

“…TGA is commonly used to study the kinetics of LCB pyrolysis and has been previously applied to predict cellulose, hemicellulose, and lignin contents. − Although the cellulose and hemicellulose measurements are consistent, the lignin measurements from previous TGA procedures are not repeatable with high confidence because these methods are built upon kinetic parameters (e.g., activation energy) that vary significantly between samples. − For example, Anca-Couce et al found significant deviations in lignin activation energies in pyrolysis-based methods, even between researchers using the same biomass feedstocks and TGA procedures . Another limitation of the pyrolysis-based approaches is that additional experiments are required to account for the remaining char content at the end of TGA runs . Other TGA characterization protocols can consistently determine the lignin content in a specific species but have not been generalized to multiple species of diverse LCB feedstocks. − Furthermore, some TGA approaches require the biomass to be fractionated prior to analysis, disrupting the chemical structure of the components prior to measurement and limiting the potential throughput by including labor-intensive steps. , Because TGA inherently measures the thermal stability of a sample, TGA also has been employed to predict technical lignin phenolic deconstruction yields in a reactive distillation-reductive catalytic deconstruction (RD-RCD) reaction .…”