Kinetic modeling of the continuous hydrothermal base catalyzed depolymerization of pine wood based kraft lignin in pilot scale

Capacity of Aqueous Solutions of the Ionic Liquid 1-Ethyl-3-methylimidazolium Acetate to Partially Depolymerize Lignin at Ambient Temperature and Pressure

“…Focusing, for instance, on the particular case of vanillin, yields in the range of 25–100 g of vanillin per kg of lignin have been reported. ,,, Nevertheless, it must be noted that the latter yields were achieved through treatments involving stages with harsh conditions: very high pH (close to 14), temperatures over 150 °C, pressurization with molecular oxygen, and organic solvents, such as nitrobenzene. Different works, ,, in the quest for greener approaches, avoided the use of highly toxic organic solvents; and, although they maintained strongly alkaline conditions, O 2 pressurization, and temperatures never lower than 120 °C, their reported yields of vanillin decreased significantly, down to the range of 2.5–13 g of vanillin per kg of lignin. In this range also lie the yields reported in the present work, which in turn have been achieved by means of treatments at ambient pressure and temperature with the only involvement of a nonflammable IL with low toxicity.…”

Lignin oligomers from mild base-catalyzed depolymerization for potential application in aqueous soy adhesive as phenolic blends

“…It was previously reported that the products were mainly lignin oligomers with a negligible number of monomers (∼3% or less). 19 Thus, separation of monomers was not carried out before the preparation of bio-adhesive. In addition, the autoclave was sealed with air.…”

“…3.1. Yield and molecular weight of lignin oligomersBernhardt et al19 have conducted hydrothermal base catalyzed depolymerization of pine wood based kraft lignin in a pilot scale. They have reported BCD experiments in two volumes of reactors, 1 L and 0.055 L. The volume of the BCD of the current work was extremely close to the 0.055 L reported.…”

Sustainable lignin modifications and processing methods: green chemistry as the way forward

“…243 Most studies focused on batch mode, but the continuous depolymerization of lignin on the pilot scale by pre-dissolving it in aqueous alkaline solutions reduces the residence time, thereby minimizing the formation of by-products. 244,245 Belkheiri et al found the control of pH (by KOH) was important when depolymerizing softwood KL in subcritical water with ZrO 2 and K 2 CO 3 as co-catalysts and phenol as the capping agent. A pH of 8.1 was optimal for minimizing repolymeriza-tion, and thus minimizing the amount of char formed (13 wt%) in a continuous pilot plant at 350 °C.…”