Abstract:
This study focused on the catalytic upgrading of bio-oils derived from fast pyrolysis of sunflower stalk, cedar, Japanese knotweed and apple tree stem over H-ZSM-5, H-beta and H-USY zeolites It is found that three zeolites have high activity and selectivity towards aromatic hydrocarbons and 56.2-100% of aromatic hydrocarbons were found in the upgraded bio-oils which can be detected by GC/MS. H-ZSM-5 produced the highest yield of aromatic hydrocarbon during the upgrading process. Furthermore, all catalysts maintained high activity and selectivity with the maximum aromatic hydrocarbons amount of 70% in the upgraded bio-oils detected in the third cycle. In addition, the spent catalysts were easily regenerated by simple calcination. Meanwhile, in order to enhance the catalytic activity and stability of zeolites, Cu/H-ZSM-5 was prepared by ion-exchange and impregnation method to adjust the acidity. When H-ZSM-5 is modified by a small amount of Cu, the selectivity can be promoted. Especially, when 0.5%Cu/H-ZSM-5 prepared by impregnation method, the yield of aromatic hydrocarbons was increased. However, if more Cu is loaded, the selectivity and surface area obviously decreases with the increase of acidity. These results indicate that the suitable amount of Cu loading is important for the catalytic performance.