Chemical Looping with Oxygen Uncoupling of the Lignocellulosic Biomass Main Model Compound: Product Distribution and Kinetic Analysis on Lignin

Product distribution and kinetic analysis of lignin were investigated during the chemical looping with oxygen uncoupling (CLOU) process. Thermodynamic simulation of the CLOU process was performed on the basis of the Gibbs free energy minimization method. The influence of the reaction temperature and mixing ratio of the oxygen carrier (CuO) on the product distribution was explored via a fixed-bed reactor combined with online mass spectrometry. Kinetic parameters from the formation of the main gas-phase products were solved by an isoconversion method. The results of the thermodynamic analysis showed that the optimal reaction conditions were 850 °C and the blending ratio of the oxygen carrier was 1.22. Overall, nearly 50% of the solid product was obtained, and the gas products from CLOU were mainly CO and CO2, accounting for more than 90%. When the temperature was raised from 700 to 850 °C, the CO2 content was reduced from 66.65 to 55.66% and the CO content was increased from 30.02 to 40.40%. The product distribution was similar to the thermodynamic simulation results. Among the gaseous products, the activation energy of H2 formation was the highest, which can reach 88.14 kJ mol-1. This study provides basic data for the thermochemical conversion of lignin and other papermaking wastes.