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(344b) Novel Approach for the Delamination of the Zeolite MCM-22

Stellato, M. - Presenter, Georgia Institute of Technology
Silva, L., São Paulo State University (UNESP)
Rodrigues, M. V., State University of Sao Paulo
Bommarius, A., Georgia Institute of Technology
Sievers, C., Georgia Institute of Technology
Martins, L., São Paulo State University (UNESP)
Zeolites are well known for their unique microporous structures that allow for highly shape‑selective catalysis and separations. One of the challenges with many zeolites is a high diffusional barrier that leads to low utilization of interior micropore volumes and faster deactivation. This can be overcome by including mesopores in the crystal structure, which shortens the diffusive path length and significantly increases transport. These can be created in a variety of ways including templating, desilication, dealumination, and delamination. However, most of these techniques involve either costly reagents, extended growth/reaction times, harsh chemicals, or some combination thereof.

To improve catalyst production at scale, it would be beneficial to develop easier and less costly methods for preparing hierarchical zeolites. One particularly interesting candidate is the delaminated zeolite ITQ-2. This hierarchical zeolite is traditionally prepared by synthesizing a layered precursor (MCM-22), which is then swollen using surfactants, kept under reflux for several hours, and sonicated in a pH monitored solution. This results in thin sheets of zeolite, only a few unit cells thick, which then stack against each other in a random arrangement creating mesopores in the delaminated ITQ-2 structure. While this method has been shown to be effective at lab scale, commercial production of delaminated zeolites would be improved with shorter processing time and fewer chemicals. In this work, we present a simplified method for producing delaminated MCM-22 without harsh post-synthesis treatments. These materials demonstrate comparable physical properties to traditionally delaminated ITQ-2 without significant loss of acid sites. They also show improved activity for the cracking of propylphenol to phenol and propylene. In addition, the rate of deactivation by coking is reduced because the diffusional path remains available longer as coke deposits accumulate. By further developing this technology, it may be possible to create other delaminated zeolites without the use of expensive treatments.