(504b) Renewable Aromatic Hydrocarbon Production from Furfural By a Continuous Dual-Stage Hydrogenation-Cocracking Process

Aromatic hydrocarbon production from furfural by catalytic cracking over zeolite catalysts is significant for realizing biobased aromatics generation, because furfural can be produced from biobased sugars through different transformation routes such as liquid phase conversion and fast pyrolysis. However, due to the high unsaturation degree and high oxygen content, direct cracking of furfural faces low aromatic hydrocarbon yield and coking problems. Therefore, in this work, two improving methods namely hydrogenation pretreatment and methanol-assisted cocracking over HZSM-5 catalyst were combined to convert furfural into aromatic hydrocarbons, and the influence of hydrogenation catalysts was investigated. It was found that in the hydrogenation stage, although the furfural was nearly completely converted over 10Cu/SiO₂, the furan ring was not efficiently hydrogenated. 5Ni-5Cu/SiO₂ and 10Ni/SiO₂ achieved the further hydrogenation of some furan rings, but over 10Ni/SiO₂ the primary conversion of furfural was lower and more saturated gaseous hydrocarbons were generated. The different hydrogenation behaviors of furfural affected the subsequent cracking processes. The hydrogenation-cocracking of furfural and methanol over 5Ni-5Cu/SiO₂ generated the highest oil phase yield of 26.4%, which was mainly composed of mono-aromatic hydrocarbons such as benzene, toluene, xylenes and trimethylbenzenes. However, because of the insufficient hydrogenation of furan ring over 10Cu/SiO₂ and the low conversion of aldehyde group as well as some excessive hydrodeoxygenation over 10Ni/SiO₂ in the hydrogenation stage, the yield and quality of the oil phases in the corresponding following cracking stage both decreased. The comparison of hydrogenation-cocracking process using the optimum hydrogenation catalyst 5Ni-5Cu/SiO₂ with other traditional cracking processes including single-stage cocracking of furfural and methanol, hydrogenation-cracking of pure furfural using 5Ni-5Cu/SiO₂ as the hydrogenation catalyst and direct cracking of furfural indicated that the hydrogenation-cocracking process was the most favorable technique for the generation of liquid aromatic hydrocarbons and the maintaining of catalyst activity. Finally, based on the experimental results, the hydrogenation-cocracking mechanism of furfural and methanol was proposed to explain the different hydrogenation behaviors of furfural over three catalysts and also the subsequent different cocracking performances.