Homocondensation of Acetone over Cation-Exchanged Granulated Hierarchical Yh Zeolites

The catalytic performance (activity and selectivity) of a FAU-type hierarchical NaYh zeolite, as well as of a series of modified samples, was investigated in the homocondensation of acetone. The modified samples were prepared from NaYh by ion exchange of Na+ for cations of alkali (Li+, K+), alkaline-earth (Ca2+, Mg2+), transition (Co2+, Ni2+), and rare-earth (La3+) metals, as well as by decationation (H-NaYh, HYh). The predominantly acidic zeolites (Ca-NaYh, Mg-NaYh, Co-NaYh, Ni-NaYh, La-NaYh, H-NaYh, and HYh) promoted the formation of acetic acid and mesitylene even at 250°C. The zeolites that contained alkali metal cations (Na+, Li+, and K+) exhibited activity only when the temperature was elevated. Starting from 350°C, NaYh and Li-NaYh promoted the formation of acetic acid. In contrast, the performance of K-NaYh under heating was characterized by the absence of acetic acid formation and a smooth increase in the selectivity towards isophorone (up to 23%) and mesitylene (up to 18%). Over the range of 400–450°C, in the presence of K-NaYh, secondary isophorone transformations were intensified, resulting in the formation of 3,5-xylenol as the main product with a selectivity of 32%.