Liquid phase alkylation of toluene with 1-heptene over a HFAU zeolite: evidence for transalkylation between toluene and non-desorbed products

The liquid phase alkylation of toluene with 1-heptene was investigated over a HFAU zeolite (Si/Al=6) under the following conditions: batch reactor, 90 degrees C, molar toluene/heptene ratio=3. Monoheptyltoluenes are rapidly f ormed, whereas biheptyltoluenes appear in low amount at high conversion. A large amount of mono, bi and triheptyltoluenes is shown to be trapped in th e zeolite pores, suggesting that alkylation is limited by product desorptio n. After total consumption of heptene, there is an increase with reaction t ime in monoheptyltoluenes trapped in the pores and a decrease in bi and tri heptyltoluenes. These observations can be explained both by a transalkylati on reaction between bi and triheptyltoluenes trapped in the zeolite micropo res and toluene molecules and by a slow diffusion of monoheptyltoluenes fro m the liquid phase to the zeolite micropores. (C) 1999 Elsevier Science B.V . All rights reserved.