The effect of crystal sizes of HZSM-5 zeolites in ethanol conversion to propylene

Three ZSM-5 zeolites with different crystal sizes were prepared and characterized by SEM, XRD, adsorption/desorption of N2, NH3-TPD, Py-IR and TG-DTA techniques. The results show that the acidic properties of HZSM-5 catalysts are very similar, but their textual properties are strongly influenced by crystal size. Their catalytic performances for the ethanol conversion to propylene were investigated in a continuous flow fixed-bed micro-reactor. In comparison with the large-sized HZSM-5, the small-sized HZSM-5 shows higher propylene selectivity and better stability, which reveals that decreasing the crystal size of zeolite is of benefit to ethanol conversion to propylene.

Different crystal size HZSM-5 catalysts for ethanol conversion to propylene were successfully prepared by different crystallization methods, and the catalyst stability and propylene selectivity are strongly influenced by the crystal size.Figure optionsDownload as PowerPoint slideHighlights
► Different crystal size ZSM-5 zeolites were successfully synthesized.
► The prepared HZSM-5 catalysts have similar Si/Al2 ratio and acidity.
► The propylene selectivity is strongly influenced by the zeolite crystal size.
► The zeolite crystal size affects greatly the catalyst stability.