Effect of silica content on production of p-Xylene from dimethylfuran/ethylene over mesoporous SiO₂-Al₂O₃ catalysts

Mesoporous SiO₂-Al₂O₃ (SA) catalysts with different SiO₂ contents were prepared, for the selective production of p-xylene from dimethylfuran/ethylene through the combination of cycloaddition and dehydrative aromatization reactions, by a co-precipitation method. For comparison, commercial SiO₂-Al₂O₃ and ZSM-5 zeolites (Si/Al₂ = 30, Si/Al₂ = 80) were also employed as catalysts in the same reaction. The pore size of the catalysts played an important role in determining the catalytic performance in the production of p-xylene. Among the catalysts tested, the order of the yield and production rate of p-xylene was as follows: mesoporous SA > commercial SiO₂-Al₂O₃ > commercial ZSM-5. In the mesoporous SA catalysts in particular, p-xylene yields showed a volcano-shaped trend with respect to the catalyst's SiO₂ content. The SA-60 catalyst, with SiO₂ = 52.3, showed the highest yield (75%) and production rate (57.7 mmol/g-cat · h) because of a catalyst structure with moderate pore size, which prevented side reactions.