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Synthesis and Characterization of Mesoporous Structures Using Carbon Particles

Douglas Moushey and Panagiotis (Peter) Smirniotis. Chemical & Materials Engineering Department, University of Cincinnati, 2600 Clifton Avenue, Cincinnati, OH 45221

A wide variety of mesoporous ZSM-12, Zeolite Beta, Y Faujasite, SBA-15, and MCM-41 were prepared by hydrothermal synthesis using carbon particles as a “co-template” for mesoporosity. The intracrystalline mesopores were formed after the included carbon black was burned. It seems that this method of generating mesoporosity can be generalized for many other zeolites. The experimental results showed that the degree of mesoporosity increased with the increase of C/Si ratio up to a certain amount. XRD results showed that for most structure types the samples remained highly crystalline at C/Si ratios as high as 1.5, and the frameworks of the mesoporous zeolites were not destroyed by the addition of carbon particles. The mesopore diameters which range from 10 nm to 50 nm were determined by nitrogen physisorption. The BET results showed that all the prepared mesoporous zeolites showed a high degree of mesoporosity. The hydroisomerization of n-heptane was chosen as a probe reaction. Compared to conventional zeolites, the mesoporous ones exhibited better selectivity and far higher activity for the isomerization of n-heptane. This behavior could be attributed to the improved mass transfer ability allowed by the mesopores. These mesoporous modifications can be employed in a wide variety of applications utilizing zeolites.