Fabrication of fluffy-ball like ZSM-5 zeolite and its application in hexane catalytic cracking

A novel fluffy-ball like ZSM-5 zeolite was prepared by biphasic hydrothermal method using hexanol and water as co-solvent. Multiple characterization technologies including XRD, SEM, TEM, N-2 adsorption-desorption, NH3-TPD, Py-IR and TG were employed to investigate physicochemical properties of fluffy-ball like ZSM-5 zeolite as well as its crystallization mechanism and deactivation in hexane cracking reaction owing to carbon deposits. The characterization results showed that this zeolite of highly controllable and uniform special morphology consisted of nanoparticles with sizes of 20-30 nm possessed higher total and mesoporous pore volumes compared with the conventional ZSM-5 sample, which not only improved diffusion efficiency but also prevented side reactions. The results of hexane cracking reaction revealed that the light olefins selectivities were improved employing this fluffy-ball like ZSM-5 (47.6%), relative to conventional coffin-like ZSM-5 (42.7%). In addition, the catalyst stability was improved greatly, which demonstrated a drop of only 3.9% in catalytic activity which was far less than 10.6% presented by conventional ZSM-5 within operation of 110 h. This new method of green, inexpensive and simple to prepare ZSM-5 may be applied to other zeolitic materials as well.