Catalytic Fast Pyrolysis Of Cellulose For Production Of Bio-based Para-xylene

With the continuous increase of energy demand and the large consumption of fossil resources,the efficient use of renewable biomass resources to produce high-value chemicals instead of fossil fuels has become one of the hot topics in the field of biomass energy and chemical industry.In this paper,metal oxide modified zeolite catalysts were optimized,and the catalytic reaction process of cellulose to bio-based p-xylene was studied.The main research results include:(1)Design and optimization of cellulose catalytic cracking catalysts.By adding P2O5 and MgO to the HZSM-5(HZ)modified catalyst,the surface acid sites and pore sizes of the zeolite catalyst were changed,thereby increasing the selectivity of para-xylene.Combined with the characterization of the catalyst,the relationship between the structure and properties of the catalyst was revealed.(2)Study on the catalytic cracking behavior of cellulose under different catalysts and different reaction conditions(temperature,additives and their contents,etc.)over the optimal catalyst-10%Mg/5%P/HZ catalyst.The difference in cellulose catalytic cracking between the in-situ and ex-situ reaction modes.The effect of surface modification of the catalyst on the isomerization of m-/o-xylene to p-xylene was investigated.Under optimized reaction conditions,the p-xylene selectivity in xylene was as high as 97.1%.(3)Based on the characterization of the catalyst and the analysis of the product,the catalytic cracking process of cellulose and its model compounds(2-methylfuran,2,5-dimethylfuran,furfural,5-methylfurfural)was studied.The reaction pathway for the preparation of p-xylene by catalytic cracking of cellulose is revealed.The main reactions include cellulose pyrolysis,Diels-Alder reaction,aromatic alkylation and xylene isomerization.