Document Type
Article
Publication Date
4-1-2021
Abstract
Microwave assisted liquefaction (MAL) of alkali lignin in ethylene glycol (EG) in the presence of hydrazine was carried out using response surface methodology. Dielectric properties of mixtures of lignin/EG at different hydrazine concentrations were determined to enhance the understanding of the MAL process. MAL parameters were hydrazine concentration (1–3%), temperature (100-180 °C), time (5-45 min) with the maximum microwave heating power limited to 750 W. Lignin/EG ratio was fixed at 1 g:10 ml. Dielectric properties were significantly influenced by hydrazine concentration and temperature. Major products from the liquefaction process (as % of peak areas) were grouped into guaiacol and derivatives (17–42%), Nitrogen compounds (0–27%), and Hydroxylated products (8–22%), and their yields were modelled with polynomial equations. Product yields were significantly influenced by process parameters. Optimum parameters for maximizing yields of guaiacol and nitrogen containing compounds were 0.5%, 180 °C, 25 min and 2.5%, 130, 25 min for hydrazine concentration, temperature, and time, respectively. Low hydrazine concentration increases guaiacol yield at higher temperatures, indicating that at high temperatures hydrazine behaves as a hydrogen donor for lignin liquefaction. The yield of nitrogen containing compounds increases at relatively low temperatures and high concentration of hydrazine. Apart from playing the respective roles of liquefaction solvent and hydrogen donor, EG and hydrazine also take part in the reaction thereby significantly modifying the composition of reaction products. A mechanistic reaction mechanism was proposed to explain the formation of the liquefaction products.
Publication Source (Journal or Book title)
Sustainable Materials and Technologies
Recommended Citation
Nde, D., Barekati-Goudarzi, M., Muley, P., Khachatryan, L., & Boldor, D. (2021). Microwave-assisted lignin liquefaction in hydrazine and ethylene glycol: Reaction pathways via response surface methodology. Sustainable Materials and Technologies, 27 https://doi.org/10.1016/j.susmat.2020.e00245
