Pyrolysis characteristics of main organic components of kraft pulping black liquor

The pyrolysis characteristics of black liquor solids (BLS) and three major organic components including alkali lignin (AL), polysaccharide (PLS) and lignin-carbohydrate complexes (LCC))were studied in a tubular furnace at 400~800℃ with 100℃ interval. The component distribution characteristics of the tar and gas were analyzed by gas chromatography with mass spectrometry (GC/MS) and gas chromatography (GC). The surface morphology and chemical structure groups of char were characterized by scanning electron microscopy (SEM) and Fourier Transforms Infrared Spectroscopy (FT-IR). The results show that the composition and distribution rules of pyrolysis products from BLS and its organic components pyrolysis are obviously different. AL, PLS and LCC have little effect on the yields of H₂ and CO from BLS pyrolysis. The yield of CO₂ from PLS pyrolysis is significantly higher than that from BLS, AL and LCC. Phenols and ethers in liquid products of BLS pyrolysis are mainly from the AL and LCC. Ketones and acids were resulted from AL, PLS, and LCC. The surface morphology of the BLS, AL, PLS, and LCC pyrolysis char is significant different. AL, PLS, and LCC affect each other in BLS pyrolysis process, and determine its pyrolysis characteristics together.