Intracrystalline mass transfer is highly restricted in zeolites and other ordered mesoporous materials due to their inherently small pore sizes. The generation of controlled network of mesopores by use of carbon black as a secondary template is investigated in this work.
Carbon black was added to the synthesis mixtures of ZSM-12, Zeolite Beta, Zeolite Y, MCM-41, and SBA-15. When the carbon was burned away, intracrystalline mesopore networks were formed. These controlled pore sizes were found to depend on the carbon particle size.
Isomerization of n-heptane was chosen to illustrate the catalytic benefits of mesoporous zeolites. Samples of ZSM-12, Zeolite Beta, and Zeolite Y with differing mesoporosity were tested. In all cases, the mesoporous structures possessed higher activity in terms of cracking under relatively high space velocity. Also, the selectivity for isomerization and the overall activity was increased in the mesoporous samples.