Creation of mesopores and structural re-organization in Beta zeolite during alkaline treatment

• Alkaline treatment is an effective method to create mesopores in Beta zeolite.
• Beta with high SAR (73) submitted to alkaline treatment suffered drastic loss in microporosity.
• Beta with low SAR (40) is a better precursor for following the stepwise transformation during alkaline treatment.
• A model of re-crystallization and re-organization of the pore structure in Beta zeolite was proposed.

Beta zeolite has a large number of applications and increasing the mesoporosity to enhance accessibility of active sites will further improve their performance. In this work we evaluated the effects of conditions of alkaline treatment (temperature and reaction time) on formation of mesoporous in Beta zeolite, starting from a Beta zeolite with SiO2/Al2O3 mole ratio (SAR) of 40 and 73. The zeolite with SAR 73 suffered drastic loss in microporosity in agreement with previous literature reports. Yet, the zeolite Beta with a lower SAR (40) showed gradual variations in properties that were followed in further details. The temperature and reaction time of the treatment that offered the best compromise between meso-area, micropore volume (MiPV) and crystallinity was found. From the characterization of the samples a model of re-crystallization and re-organization of the pore structure during mesopore formation in Beta zeolite was proposed.

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