Enhancement in the Catalytic Activity of Gacl3 Supported on Si-MCM-41, Mont. K-10 Clay and H-Beta Zeolite by its Thermal Activation for the Benzylation of Benzene and Benzoylation P-Xylene
Heterogeneous catalysts GaCl3/Si-MCM-41, GaCl3/Mont. K-10 clay and GaCl3/H-beta zeolite with GaCl3
loading of 0.5-2.0 mmol.g-1 prepared by impregnation and thermally activated (95-600 C) under the flow of N2 or air
showed high catalytic activity towards the friedel-Crafts type benzylation of benzene and benzoylation p-xylene. Formation of
new catalytically active surface species –O-GaCl2 and/or (-O)2GaCl by the solid-solid reaction between the supported GaCl3
and the surface hydroxyls of the catalyst support occurs at high temperatures which are responsible for the enhanced catalytic
activity of these catalysts. The prepared catalysts were also found to be stable under air/moisture with no effect on its catalytic
activity. The -GaClx are chemically bonded to the support by -O- linakges. High turn-over frequency and shorter reaction
times where observed in all the cases. Effects of reaction parameters such as catalyst calcination temperature, atmosphere of
calcination, catalyst loading were also studied. Among the thermally activated supported GaCl3 catalysts, GaCl3/Mont.K-10
and GaCl3/H-beta with the Fe-loading of 1.0 mmol/g show best results in the benzylation and benzoylation reactions,
respectively, due to redox and acidic properties, such as clayzic, supported oxides and chlorides of iron.
Index Terms - Friedel-Crafts reaction, Heterogeneous, GaCl3, Thermally activated.