Catalytic Conversion Of Biomass-derived Polyols Into Para-Xylene Over SiO₂-modified Zeolites

Biomass is the only resource that can replace fossil resources and provide renewable carbon.In recent years,the development and utilization of sugar alcohols from renewable lignocellulosic materials to produce high-value chemicals has attracted wide attention.The aim of this paper is to explore the directional synthesis of high-value chemical terephthalene from biomass-based polyols.The main research results include:(1)Design and optimization of catalysts for catalytic cracking of polyols.A functional catalyst(15%SiO2/HZSM-5)for catalytic cracking of biomass-based polyols and directional isomerization of xylene was developed.The selectivity of p-xylene was enhanced by surface modification of metal oxides to modify the acidic sites and pore size of zeolites.The relationship between the structure and performance of the catalyst was revealed by the characterization of the catalyst.(2)Study on the preparation of p-Xylene by catalytic pyrolysis of polyols.The catalytic cracking behavior of polyols under different reaction conditions(temperature,space velocity,additives,etc.)and the catalytic effect of surface modification on the directional isomerization of o/m-xylene to p-xylene were studied.Under the optimized reaction conditions,the selectivity of p-xylene in xylene reached 91.1%C-mol%.(3)Based on the analysis of products and the characterization of catalysts,the possible reaction pathways for the synthesis of p-xylene from biomass-based polyols were proposed,including polyol cracking,deoxidation,olefin aromatization,aromatic alkylation and xylene isomerization.