Studies On The Production Of Propene From FCC Dry Gas And Mixed C₄

To improve the utilization of FCC dry gas and mixed C₄, reaction conditions optimization and catalysts design were investigated systemically with the combined feed of FCC dry gas and mixed C₄, converting the light olefins to high value-added product, i.e. propene.Reactions catalyzed by ZSM-5 solid acidic catalysts at 450oC were carried out in the fixed-bed micro-reactor with the combined feed of FCC dry gas and mixed C₄. Synergism of co-reaction of ethene and butene in producing propene was found through series of experiments, which showed the feasibility of the route. Reaction conditions, including mixing radio, space velocity and reaction temperature, were investigated.The catalytic performance of zeolites with various structures was investigated and it was found that ZSM-5 with suitable pore size and acidic properties exhibited better performance. Higher Si/Al ratio was beneficial to the increase of propene selectivity, resulting from its low acidity suppressing the secondary reaction of the alkenes. Effects of calcination temperature and Al/Zr ratio on the catalytic performance were studied when Zr-Al composite oxides were applied as support.MoO3 was introduced into the traditional solid acidic catalyst to realize the coupling of the cracking reaction and metathesis reaction. The physico-chemical properties of ZSM-5, Mo/ZSM-5 and Mo-ZSM-5 were characterized with XRD, FT-IR, NH₃-TPD, and the results were correlated with respective catalytic performance. The investigation of Mo content on the catalytic performance demonstrated the importance of acidity of Mo/ZSM-5 catayst, which was prepared by impregnation method, and the interaction between molybdenum and ZSM-5-Al₂O₃ support. Effects of MoO3 loading, pH, along with calcination temperature, were also investigated. Based on the hydrogen bond theory, the mechanism of the change of surface acidic properties of Mo-ZSM-5 sample prepared by hydrothermal method was proposed. Moreover, hydrothermal method favored the dispersion of Mo species, generating more metathesis active sites, which was beneficial to the formation of propene.In conclusion, ethene and butene could be rationally utilized by co-reaction of FCC dry gas and mixed C₄ with suitable reaction conditions and proper catalyst to maximize propene, achieving the goal of maximizing propene. The study provided a novel way for producing propene from FCC dry gas and mixed C₄, which exhibited potential industrial value.