Co-cracking of bio-oil model compound mixtures and ethanol over different metal oxide-modified HZSM-5 catalysts

The distilled fraction of bio-oil can be converted into aromatic hydrocarbons via co-cracking with ethanol over the catalyst of Hydrogen Zeolite Socony Mobile-Five (HZSM-5). To further improve the selectivity of aromatics, the influences of different metal oxides loaded onto HZSM-5 were investigated and a range of model compounds were selected and mixed to simulate the distilled fraction of bio-oil. Two model compound mixtures (MCM) were used for co-cracking with ethanol: (1) MCM-1 that contains hydroxypropanone, cyclopentanone and acetic acid and (2) MCM-2 that contains hydroxypropanone, cyclopentanone, acetic acid, phenol and guaiacol. Co-cracking of MCM-1 and ethanol over ZnO/HZSM-5 and Ga2O3/HZSM-5 generated higher selectivities of oil phases than that found using HZSM-5 and CuO/HZSM-5. However, during the co-cracking of MCM-2 and ethanol, ZnO/HZSM-5 and CuO/HZSM-5 were seriously deactivated resulting in low selectivities of the oil phases. The characterization of the spent catalysts showed that the inner pores in these two catalysts were completely blocked. Meanwhile, Ga2O3/HZSM-5 still showed better performance than HZSM-5 for the co-cracking of MCM-2 and ethanol.