Cascade method for extracting high-value compounds from corn straw by combining hydrothermal pretreatment and catalytic pyrolysis

The production of high-value chemicals through the targeted pyrolysis of biomass can achieves the utilization of biomass waste as an energy source. This study presents a method for preparing high value-added bio-oil by integrating hydrothermal pretreatment (HTP) of corn straw (CS) with catalytic pyrolysis. The evolution of the physicochemical structure of pretreated samples under different conditions was detailed analyzed and the effects of HTP on the composition and distribution of pyrolysis products was investigated. Furthermore, different types of zeolite catalysts, including USY, Beta, and ZSM-5, were employed for the catalytic pyrolysis of HTP-treated samples. The results showed that HTP significantly enhanced the energy density of CS and modified its pyrolysis characteristics. The glucopyranose yield in HTP-treated samples substantially exceeded that of untreated CS. Owing to variations in the distribution of surface acidic sites and pore structures, different zeolite types exhibited distinct impacts on the composition and distribution of bio-oil components, particularly in enhancing the yield of aromatic compounds. Notably, the aromatic yield of CS160 showed a 1.6-fold increase compared to untreated CS when subjected to ZSM-5 catalytic pyrolysis. This study provides significant guidance for the preparation of high-value chemicals from biomass resources.