(66i) Fractionation of Depolymerized Lignin Streams Using Tangential Flow Filtration

Growing demand for fuels, chemicals, and materials from renewable sources is driving innovation in the conversion of lignocellulosic biomass through biorefineries. Lignin, an environmentally sustainable carbon source, and the second most abundant terrestrial polymer, molecules can vary between 1000 Da and 100,000 Da. With different molecular weight (MW) distributions, they could be used in low-cost carbon fibers, engineering plastics, thermoplastic elastomers, polymer foams, sheet adhesives, and a variety of fuels and chemicals. Precise fractions are regarded as a key procedure to enable efficient and economically viable conversion of lignin to value-added products.¹

In this talk, the performance of a cascading Tangential Flow Filtration (TFF)² for fractionation of the depolymerized lignin streams is presented. TFF systems with different membrane cut-offs (0.5 μm, 25 kDa, 5 kDa, 2 kDa, 1 kDa, to nano) are employed to separate different MW of lignin streams. Different lignin streams made from alkali and ionic liquid pretreatment of corn stover, reductive catalytic fractionation (RCF) of poplar,³ and oxidative catalytic fractionation (OCF) of poplar,⁴ are investigated respectively. A series of analyses such as lignin molecular weight, monomeric sugars, oligosaccharides, and the rheology properties of the streams from different molecular weight cut-off membranes is conducted to understand the lignin fractions, optimize the separation process, and determine the future application. Techno-economic analysis (TEA) results show that a high initial concentration in the liquid stream plays a critical role in the product yield and recovery cost.⁵

1 Ragauskas, Arthur J., et al. "Lignin valorization: improving lignin processing in the biorefinery." science 344.6185 (2014): 1246843.

2 Van Reis, Robert, et al. "High performance tangential flow filtration." Biotechnology and bioengineering 56.1 (1997): 71-82

3 Anderson, Eric M., et al. "Flowthrough reductive catalytic fractionation of biomass." Joule 1.3 (2017): 613-622.

4 Luo, Hao, et al. "Oxidative catalytic fractionation of lignocellulosic biomass under non-alkaline conditions." Journal of the American Chemical Society 143.37 (2021): 15462-15470

5 Yan, Jipeng, et al. "Fractionation of Lignin Streams Using Tangential Flow Filtration." Industrial & Engineering Chemistry Research (2022).