Toluene methylation with methanol over bi-porous acidic and basic zeolite catalysts: Synthesis, characterization and kinetic modeling

Toluene methylation with methanol was carried out over different bi-porous acidic composite HZSM-5/Almcm41 (ZM1, ZM2 and ZM3) and CsX modified basic catalysts. The porosity of the catalysts was adjusted through different degree of ZSM-5 dissolution via the top down approach. The textural properties of the composite catalysts were probed through various characterization techniques. The activity of the catalysts were compared with the parent ZSM-5 and MCM-41 with respect to toluene methylation and toluene disproportionation at different toluene to methanol molar feed ratios (6:1,3:1,1:1,1:3 and 1:6).;The meso porous catalysts (ZM3 and AlMCM-41) were less active, whereas ZM2 with 47% meso content showed the best catalytic activity with the highest mixed xylenes production and lowest toluene disproportion (measure through benzene formation) at all the molar feed ratio.;Kinetic study was carried out on ZM2, MOR/ZSM5 (composite mono porous) and HZSM-5 in a fluidized reactor at different temperatures and reaction time. Simplified power model was developed to account for toluene conversion (methylation and disproportionation) and catalyst deactivation. The activation energy, reaction rate constant and catalyst deactivation were all estimated through the kinetic modeling.;For the basic catalyst, CsX was synthesized through ion exchange method, its basicity was increased by loading more Cs2O and ZrBO3 was also added to it (CsX) through mechanical mixing. The promoting effects of these additives were studied for side-chain methylation of toluene to styrene at different toluene to methanol molar feed ratio. ZrBO3/CsX increases both toluene conversion and styrene selectivity while Cs2O/CsX increases toluene conversion and reduces styrene selectivity.