Co-pyrolysis characteristics of polysaccharides-cellulose and the co-pyrolyzed compound distributions over two kinds of zeolite catalysts

Co-pyrolysis characteristics of soluble polysaccharides-cellulose were investigated through thermogravimetric analysis (TGA), kinetic analysis, analytical pyrolyser coupled with gas chromatograph-mass spectrometer (Py-GC/MS) and subsequent density functional theory (DFT). Results from TGA and differential thermogravimetric analysis (DTG) analyses indicated that there were synergistic effects in the polysaccharides-cellulose (PS-CE) blends pyrolysis process. Surprisingly in co-pyrolysis process from Py-GC/MS analysis, the furans were suppressed, while the anhydrosugars were increased. The DFT calculation showed that free radicals pyrolyzed from soluble polysaccharides could suppress the ring-opening reaction of D-glucopyranose. The co-pyrolyzed chemical compound distribution over the catalysts (MCM-41, ZSM-5 and their mixtures) was also detected through Py-GC/MS analysis. Both the zeolites showed high selectivity for 5-methyl-2-furaldehyde and 2-furaldehyde. The two kinds of zeolites could induce the generation of furans but suppress the production of anhydrosugars, which was the opposite effect of the co-pyrolysis of PS-CE.