Pyrolysis of lignin (De-alkaline) via TG/DSC-FTIR and TG-MS: pyrolysis characteristics, thermo-kinetics, and gas products

The pyrolysis characteristics of lignin (De-alkaline) were evaluated using TG/DSC-FTIR and TG-MS. TGA experiments indicated that the pyrolysis of lignin (De-alkaline) proceeded in three stages between 303.15 to 1173.15 K, and the thermographs shifted to higher temperatures with increasing heating rate from 10 to 40 K center dot min(-1). Gases FTIR correspondingly showed that the characteristic absorption peaks of corresponding functional groups increased with the increase of pyrolysis temperature at 423, 623, 823, and 1023 K. For TG-MS tests, H-2, CH4, CO, and CO2 were mainly produced in the temperature range 500-700 K, and CO and CO2 were also produced between 950 and 1050 K. The kinetic triplets of lignin (De-alkaline) pyrolysis were estimated by Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Coats-Redfern, and integral Master-plots methods. The activation energy of three stages used to calculate the experimental curve was the average value of FWO and KAS methods (58.95, 206.19, and 317.17 kJ center dot mol(-1), respectively). Kinetic reaction mechanisms predicted using the integral Master-plots were f(alpha) = (1-alpha)(1.3), f(alpha) = (1-alpha)(3.9), and f(alpha) = 2.7(1-alpha)[-ln(1-alpha)]((1-1/2.7)) for the three stages, respectively. This study provides a theoretical and practical guideline to meeting the engineering challenges based on the pyrolysis of lignin from papermaking wastewater.

Automated summary

The pyrolysis characteristics of de-alkaline lignin were studied using TG/DSC-FTIR and TG-MS. The results showed that the pyrolysis of lignin proceeded in three stages and the temperature increased with the heating rate. The main pyrolysis products were H-2, CH4, CO, and CO2. The activation energy and reaction mechanisms were determined through kinetic analysis.