Role of pretreatment with acid and base on the distribution of the products obtained via lignocellulosic biomass pyrolysis

Abstract

The pretreatment of biomass could change the distribution of liquid products in pyrolysis. In this study, by controlling acid and base content in solutions, the pyrolysis of corncob pretreated by acid and basic solutions in boiling water were conducted. The results showed that different acid and base content in the pretreatment solution induced different liquid product distribution: the yield of furfural reached as high as 77% when the mass ratio of acid and corncob was 0.1 : 1, levoglucosenone (8.7%) was produced when H₂SO₄ : corncob = 0.01 : 1, the high value-added chemicals like 4-vinyl guaiacol (6.3%), 2,3-dihydrobenzofuran (6.7%) and 1,2-cyclopentanedione (6.7%) could be obtained when H₂SO₄ : corncob = 0.001 : 1, high yield of methanol (11.3%), benzene (22%), and 1-hydroxy-2-butanone (7.5%) were produced when NaOH : corncob = 0.08 : 1. Besides, the chemical varieties were different. For example, levoglucosenone could only be obtained when the ratio of acid and corncob was about 0.01 : 1, while 4-vinyl guaiacol and 2,3-dihydrobenzofuran could not be produced. More than that, pretreatment could also change the yields of gas and liquid during pyrolysis, but the yields of solid or bio-char remained constant. Meanwhile, the pretreatment by this method could lower the temperature of corncob pyrolysis compared with pretreatment by boiling water only.