Upgrading of biomass fast pyrolysis oil over a moving bed of coal char

Fast pyrolysis of sawdust(SD)and upgrading of the derived bio-oil*(water-free basis)over Shenmu bituminous coal char(SMC)were conducted in an integrated free fall pyrolyzer and moving bed upgrading reactor.The water soluble and heavy bio-oil*(THF soluble)yields decrease and the content of light bio-oil*(CH_(2)Cl_(2) soluble)increases significantly compared that without SMC despite the decrease of light bio-oil*yield.Chemical analyses of the light bio-oil*were performed using GC-MS and ^(1)H NMR techniques.The results show that during volatiles-char interaction,the SMC plays important roles in deoxygenation and denitrogenation.The role of SMC in the upgrading process was explored by BET,FT-IR and XRD characterization.The porous structure provides reaction active sites for the bio-oil upgrading.After volatiles-char interaction,the specific surface area of SMC decreases significantly and the carbon crystallite size increases.With increasing the char updating rate from 1 g/min to 4 g/min,the relatively fresh SMC surface leads to the increased active sites,the conversion of heavy bio-oil*is slightly promoted and the removal effects of heteroatoms(O,N)compounds in the light bio-oil*are enhanced.The changes in SMC specific surface area and microcrystalline size are weakened accordingly.