Experimental and kinetic studies of ethyltoluenes production via different alkylation reactions

• Toluene ethylation proceeds faster than methylation of EB over ZSM-5 and MOR.
• Kinetic parameters were obtained for toluene ethylation followed by isomerization.
• ZSM-5 requires higher activation energy for initial ethylation step compared to MOR.
• Silylation of ZSM-5 yielded a 100% para-selective ethylation catalyst.

Ethyltoluenes production via two alkylation reactions vis: toluene ethylation and ethylbenzene (EB) methylation on ZSM-5 and mordenite (MOR) was studied in a batch fluidized-bed reactor at a temperature range of 200–300 °C for reaction times of 5–20 s. Toluene ethylation with ethanol gave better yield and selectivity to ethyltoluenes on ZSM-5 compared with EB methylation with methanol. A maximum ethyltoluenes yield of 22.0% was achieved during toluene ethylation whereas 7.3% yield was attained in EB methylation on ZSM-5. To achieve enhanced para-ethyltoluene selectivity, ZSM-5 was modified by silylation treatment using tetraethyl orthosilicate (TEOS). While toluene conversion on silylated ZSM-5 (HZ80-6L) was decreased, 100% para-isomer selectivity was obtained due to the reduction of the effective pore channel and strength of acid sites. A comprehensive kinetic study of the toluene ethylation reaction is reported in this paper using the power-law approach for the model development. A satisfactory correlation between experimental data and the model result was achieved. The required apparent activation energy for the alkylation step of toluene ethylation reaction over ZSM-5, HZ80-6L and MOR catalysts was determined to be 70 kJ/mol, 63 kJ/mol and 28 kJ/mol, respectively.

Plausible reaction pathway for toluene alkylation with ethanol.Figure optionsDownload high-quality image (74 K)Download as PowerPoint slide