Production of bio-based p-xylene via catalytic pyrolysis of biomass over metal oxide-modified HZSM-5 zeolites

BACKGROUNDp-Xylene is an important bulk chemical in the petrochemical industry, and the production of bio-based p-xylene is of great significance in both academic and industrial arenas. However, the biggest challenge for the production of p-xylene from biomass is how to increase the yield and selectivity of p-xylene. RESULTSThe highest p-xylene yield of 20.7C-mol% with a p-xylene/xylenes ratio of 91.6% was obtained by the co-catalytic pyrolysis of sawdust with 50wt% methanol over the 20%La2O3/HZSM-5(80) catalyst. Adding a La, Mg, Ce or Zn element into HZSM-5 promoted the alkylation of benzene and toluene to form xylenes, and the isomerization of m/o-xylenes to p-xylene. CONCLUSIONThis work developed a one-pot process in which lignocellulosic biomass (sawdust) was directionally converted into p-xylene by coupling the catalytic pyrolysis of biomass into aromatic monomers, the alkylation of light aromatics to xylenes and the isomerization of m/o-xylenes to p-xylene over the metal oxide-modified HZSM-5 catalysts. The selectivity and yield of p-xylene strongly depended on the acidity of the catalysts, reaction temperature and methanol additive during the catalytic pyrolysis of sawdust. (c) 2018 Society of Chemical Industry