Activity, selectivity, and deactivation of high-sodium HY zeolite

Abstract

The effect of deactivation on the activity and selectivity of (very high) Na + content HY zeolite catalysts was studied in a pulse microreactor equipped with a thermogravimetric analysis unit (TGA). Cumene was used as the reactant. The Na + level studied was from 3.2 to 11.8% of Na 2O. As the Na + content decreases, the acidity of the zeolite increases and deactivation decreases. The effect of coke level on selectivity to benzene, toluene, ethylbenzene, dimethylbenzene, ethyltoluene, cymene, and diisopropylbenzene depends on the Na + content. For example, the selectivity to benzene, the major aromatic formed by the fresh catalyst, decreases with increasing coke level and Na + level, while the selectivity to ethyltoluene increases under the same conditions. A maximum in selectivity with coke level is obtained for most other products. At intermediate Na + levels (around 7% Na 2O), ethylbenzene shows a maximum in selectivity while cymene passes through a minimum. The maximum coke deposition and the coke level for the maximum incremental coke deposition are two important parameters that distinguish conversion and selectivity patterns.