Tailoring the preparation of USY zeolite with uniform mesoporosity for improved catalytic activity in phenol/isopropanol alkylation

The procedure involved the use of temperatures within 40–135 °C, a low ammonia concentration solution (0.05 N) and hydrothermal synthesis times of 20 h. When working at 40–80 °C, the obtained USY simples exhibit enhanced intraparticular mesoporosity (324–418 m2 g-1), showing increasingly uniform mesopores around 4.0 nm, while holding a remarkable zeolitic microporosity (413–363 m2 g-1).

In contrast, higher temperaturas resulted in a steady abatement of crystalline zeolitic domains, with a total collapse of the zeolite structure at 135 °C. These hierarchical USY materials were tested in the alkylation of phenol with isopropanol, wherein one of the obtained products, e.g. 2,6-diisopropylphenol (Propofol), is the most important intravenous anaesthetic in the market. Interestingly, the generation of the uniform mesoporosity in USY samples led to an enhancement of both the phenol conversion and the selectivity towards C-alkylation products.