Enhancing and upgrading bio-oil during catalytic pyrolysis of cellulose: The synergistic effect of potassium cation and different anions impregnation

Aiming to investigate the synergistic effect of K+ and anions on the primary products of microcrystalline cellulose (MCC) pyrolysis. MCC was impregnated with KHCO3, KCI, K2CO3 and KOH. The GC/MS and TG-FTIR were used to investigate the volatiles during pyrolysis and catalytic pyrolysis, as well as the product distribution of pyrolytic bio-oil obtained from fixed bed reactor, respectively. It was found that the synergistic effect of K+ and anions could catalyze the pyrolytic decomposition of MCC through ring cleavage, catalytic cracking, cyclization and dehydration reactions, thus enhancing the liquid product yield and upgrading pyrolysis bio-oil. KHCO3 was the most effective in producing and upgrading bio-oil, the liquid yield increased from 44.29% (MCC) to 59.27% (0.10 KHCO3-MCC), and the yield of furanic compounds (5-hydroxymethylfurfural, furfural) and other 0-containing compounds increased from 9.88% (MCC) to 19.84% (0.10 KHCO3-MCC), 18.54% (MCC) to 46.47% (0.10 KHCO3-MCC), respectively. The yield of levoglucosan decreased from 66.21% (MCC) to 22.95% (0.10 KHCO3MCC). The formation of levoglucosan was inhibited through ring scission of pyran directly, leading to the cleavage of 1,4-glycosidic linkage, and low molecular weight compounds were produced as platform chemical for the production of a wide spectrum of sustainable bioproducts and biofuels.