Abstract
Substitution of transition metals in the AlPO4-5 framework was found to afford novel heterogeneous catalysts for the transalkylation of toluene (T) with trimethylbenzenes (TMBs). The activity of MeAPO-5 catalysts follows the order of SiAPO > MgAPO > MnAPO > ZnAPO > CoAPO which can be correlated with the acid properties of catalysts. The same correlation was found for MeAPSO-5 catalysts. The strength of acid sites of the catalyst influences the competition among various reactions that occur during the transalkylation process. Generally, the transalkylation and/or disproportionation reactions occur on stronger acid sites, while the isomerization of xylenes (Xs) and TMBs predominate on weaker acid sites.