Influence mechanism of torrefaction on softwood pyrolysis based on structural analysis and kinetic modeling. (5th October 2016)

• Record Type: Journal Article
• Authors: Wang, Shurong; Ru, Bin; Dai, Gongxin; Lin, Haizhou; Zhang, Li
• Is Part Of: International journal of hydrogen energy. Volume 41:Number 37(2016)
• Page Start: 16428
• Page End: 16435
• Publication Date: 2016-10-05
• Subjects: Biomass -- Torrefaction -- Pyrolysis -- Kinetic model -- 13C CP/MAS NMR; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2016.02.082
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: The influence mechanism of torrefaction on biomass pyrolysis was studied in detail. 13 C CP/MAS NMR was employed to characterize the evolution of functional groups during torrefaction, indicating that hemicellulose was extensively deacetylated and depolymerized; the crystalline structure of cellulose was destroyed; and the aryl ether linkages and propyl side branches in lignin were cleaved. A distributed activation energy model with three combined Gaussian functions was introduced to analyze the pyrolysis kinetics of biomass. The mean activation energies for three parallel reactions remained unchanged after torrefaction, while the weighing factors proved that their contributions to devolatilization largely changed. Acetic acid yield significantly decreased after torrefaction, with reduction of the yields of 5-hydroxymethylfurfural and levoglucosan because of the depolymerization of carbohydrates during torrefaction. Due to the dissociation of propyl branches and the demethylation of methoxyls in lignin, pyrolysis of torrefied biomass yielded more guaiacol and catechol and less phenols with C4-propyl groups. Graphical abstract: Highlights: Ordered crystalline structure of cellulose was destroyed during torrefaction. Deacetylation, depolymerization and aryl ether cleavage were revealed by solid NMR. The parallel reaction contributions to devolatilization were analyzed by 3G-DAEM. Abundances of typical pyrolytic products largely changed after torrefaction.