Disproportionation of trimethyl benzenes over large pore zeolites: catalytic and adsorption study

Comparison of Activity and Selectivity of SSZ-33 Based Catalyst with other Zeolites in Toluene Disproportionation

“…The apparent activation energies for bimolecular transalkylation reactions were found to decrease as follows: E(transalkylation) [ E(isomerization) [ E(disproportionation). Substantially higher reactivity of trimethylbenzenes compared with toluene was confirmed over different structural types of zeolites, namely beta, mordenite, and Y [23].…”

Catalytic transformation of C7–C9 methyl benzenes over USY-based FCC zeolite catalyst

“…They determined the intrinsic kinetic parameters for both isomerization and disproportionation reactions. Cejka et al [24] studied the effect of the structure of large pore zeolites on the activity, selectivity and time-on-stream in trimethylbenzene disproportionation. They used zeolites of beta, Y, L and mordenite types which exhibited significant difference in conversion and T-O-S.…”

“…Two different reaction pathways were proposed, i.e., methyl transfer mechanism (formation of a methoxy group on the zeolite surface) and the diphenyl methane mechanism. It was shown that toluene disproportionation does not require Brönsted acid sites of a high acid strength www.elsevier.com/locate/apcata Applied Catalysis A: General 305 (2006) [21][22][23][24][25][26][27][28][29][30][31] (present in H-ZSM-5 zeolite) to proceed, and the rate of the reaction is controlled by the concentration of acid sites, which is higher in zeolite Y compared to H-ZSM-5 [1]. Olson and Haag [6] indicated that for para-selective toluene disproportionation, the primary toluene disproportionation to xylenes, and the subsequent xylene isomerization to p-xylene should be controlled to achieve higher than equilibrium concentration of p-xylene by ensuring that the reaction is not diffusion limited and the diffusivity of p-xylene in the zeolite channel is higher compared to o-and m-xylene.…”

Transformation of thiophenic compounds over acidic zeolites

“…HMOR zeolite presents a rapid and practically total deactivation after 8 h of reaction ( Fig. 9) as was the case for trimethylbenzenes disproportionation [42]. The pore system of this zeolite (a 12-membered ring zeolite like HY and Hb zeolites) is monodimensionnal and the coke can completely plug the mouth of the channels.…”