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Catalytic performance of modified beta zeolite on the synthesis of styrene and xylene: a kinetic study

ABSTRACT The catalytic performance of K-modified zeolite beta (Kβ) was investigated for the synthesis of industrially important products styrene and xylene by alkylation of toluene with methanol. A series of beta zeolites Kβ0.25, Kβ0.5, Kβ1.0 and Kβ1.5 were prepared by modification with different concentration of potassium chloride solution (0.25%, 5%, 1.0% and 1.5%). The modified zeolites were characterised by XRD, SEM, EDS and FTIR. Toluene and methanol in a molar ratio of 0.5:1–7:1 were subjected to vapour phase alkylation reaction in the temperature range of 733–793 K, space-time 0.009–0.025 kgh/kmol at 1 atm pressure. However, maximum toluene conversion was achieved at temperature 773 K, reactant ratio 2.5:1 and space-time 0.010 kgh/kmol over catalyst Kβ0.25. After modification with K, the acidic Hbeta zeolite become partly basic in nature. A kinetic model was evaluated to find the reaction constants. The activation energy of ring alkylation was found to be 76 kJ/mol.