Study On Catalytic Reforming Of Cellulose Pyrolysis Vapors To Produce Long-Chain Alkanes

Bio-derived fatty acids or fatty acid alkyl esters were often used as raw material to be transformed into alkanes via hydrodeoxygenation,harsh conditions were essential in the established methods,such as high pressure(pressures>2MPa)and high H2 consumption(≥3 M ratio of H2 per reactant).This work was devoted to catalytic conversion cellulose pyrolysis vapors directly into long-chain alkanes directly without extra hydrogen at ordinary pressures,using hydrogen sources inside the reaction system,which provided a new idea and method for preparing liquid alkanes fuel.Nb2O5,γ-Al2O3,ZSM-5 and TS-1,four catalyst carriers with high catalytic activity in oxygen-containing reactions,were selected for characterization analysis and catalytic upgrading of cellulose pyrolysis vapors via Py-GC/MS.And the relationship between the physicochemical properties of different catalysts and their selectivity to alkanes was discussed.The deoxidation performance of the catalyst was in the order of ZSM-5>y-A12O3>TS-1>Nb2O5,the selectivity of alkanes was in the order of TS-1>ZSM-5>y-Al2O3>Nb2O5,so TS-1 was selected as the best catalyst carrier for alkanes production.In addition,TS-1 was supported with Co,Mo,Pt and Au for catalytic pyrolysis of cellulose.The results showed that Au/TS-1 catalyst was the most suitable for this study,and the selectivity of alkanes reached 47.8%.Au/TS-1 catalyst with a load of 0.5,1.0,1.5,2.0 wt.%was prepared to further optimize the process conditions.Four factors that may influence the results with the content of Au loading,mass ratio of catalyst to cellulose,pyrolysis and catalytic temperature were tested.The results showed that the alkanes had the highest selectivity and yield(89.2%and 14.4 wt%,respectively)in the condition that the content of Au loading was 1%,mass ratio of catalyst to cellulose was 50,pyrolysis temperature was 350℃ and catalytic temperature was 500℃.The catalysts were characterized to analyze relationship between the physicochemical properties of different catalysts and their selectivity to long-chain alkanes.Cellobiose,glucose and anhydroglucose were used for the pyrolysis and catalytic pyrolysis experiments to prove that long-chain alkanes were generated by the growth by the combination of short-chain compounds over Au/TS-1.Methanol and acetaldehyde,two model compounds with representative functional groups,showed that the alkanes were mainly generated from alcohols.