Scholarly record

KINETIC MODELLING OF HYDROLYZED LIGNIN PYROLYSIS USING THERMAL ANALYSIS

T.R. Musin, M.A. Varfolomeev, Alexander Gerasimov, Mustafa Versan KOK

Abstract

Every day more than 60 tons of hydrolyzed lignin are produced only on one bioethanol manufacturing factory, 25000 tons per year. More than 1 million tons of lignin is produced by wood-recycling factories worldwide, which is being combusted to compensate energy costs or just stored as a waste. We suppose that there is a more sufficient way of its recycling and provide another way of lignin use, assuming the pyrolysis process as one of the pretreatment methods of its reproduction into more favorable derivatives. Pyrolysis as a technological process needs its techniques and facilities therefore we assume it is necessary to know kinetics of pyrolysis. In this study, pyrolysis of hydrolyzed lignin was investigated as a first stage of lignin pretreatment purposed to obtain favorable low molecular compounds. TG, DSC and MS analysis were performed with following full investigation of the mass changes, heat effects and volatiles of the pyrolysis process. Kinetic analysis was based on the TG data. Parameters of pyrolysis were calculated, using different isoconversional kinetic methods. Results of model-free kinetics then were used for model elaboration as a starting point for calculations. Results of TG, DSC and MS analysis at different heating rates showed that process of lignin decomposition contain four stages. Main products of pyrolysis are water, carbon oxides and hydrocarbons. Water mostly emits on first and second stages of thermal decomposition, carbon oxides appear on second and third stages and hydrocarbons characterize last two stages of pyrolysis. Kinetic analysis was performed for TG data using NETZSCH Thermokinetics software. Calculations include both model-free and model-fitting methods. Best fitted model is a sequential three-step reaction, where last two steps indicate pyrolysis stages. Activation energies for pyrolysis process locate in wide range from 75 up to 230 kJ/mol depending on stage.

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DOI resolver: doi.org/10.5593/sgem2017h/43/s18.013

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