Catalytic co-conversion of poplar pyrolysis vapor and methanol for aromatics production via ex-situ configuration

The ex-situ catalytic co-conversion of poplar pyrolysis vapor and methanol over HZSM-5 was conducted in a bench-scale continuous feeding setup. Methanol was introduced into reaction system through mid-section addition. The effects of catalytic temperature, methanol/poplar mass ratio, time-on-stream on the products distribution and bio-oil composition were investigated. In addition, the evident synergistic effects for promotion of aromatics and reduction of coke were revealed in the co-conversion process. Under the mid-section methanol addition system, aromatics especially monoaromatics in bio-oil increased significantly while the phenolics and other oxygenates reduced considerably to a rather low level. When the catalytic temperature and methanol/poplar mass ratio were 500 ℃ and 1.5:1, the maximum aromatics yield of 9.54 wt% was obtained with organics yield enhanced to 22.49 wt%. Meanwhile, the positive synergistic effect for aromatics and the negative synergistic effect for coke achieved 90.12% and 29.82% respectively. The mid-section methanol addition also successfully prolonged the lifetime of catalyst by 50% compared to poplar single-conversion. The characterization of catalysts indicated that the BET specific surface area for co-conversion exhibited a minor change with 1.3% reduction after regeneration. The acidity of regenerated catalyst in co-conversion was also stronger than that in poplar single-conversion. The reusability of catalyst didn’t decrease to a certain extent until the fourth reaction-regeneration recycle run. This paper proposed a new efficient co-utilization strategy for biomass and methanol, which stimulated the strong synergistic effect between the two feedstocks.