Conversion of methanol with C5–C6 hydrocarbons into aromatics in a two-stage fluidized bed reactor

• The mixed feed conversion suppressed the self-decomposition of methanol.
• Methanol to pentane ratios increased the aromatic yield.
• Methanol addition suppressed the formation of propane from cyclohexane.

The conversion of methanol mixed with C5–C6 hydrocarbons (including pentane, hexane, and cyclohexane) was studied in a two-stage fluidized bed reactor packed with 880 g Zn/ZSM-5 catalyst at 475 °C and 0.4 MPa. The effect of the mixed feed on the methanol conversion, self-decomposition of methanol, coke deposition on the catalyst, aromatic yield, and the aromatic distribution was carefully studied. Methanol conversion was nearly complete and the self-decomposition of methanol can be suppressed significantly. There exhibited a positive heat coupling effect in the feeding of methanol with pentane or with cyclohexane to increase the aromatic yield or to suppress the undesirable side reactions. However, the mixed feed is unfavorable to the transformation of hexane into aromatics. Better aromatic yield in the lower temperature for the mixed feed, as compared to that for the conversion of pure C5–C6 hydrocarbons in higher temperature, validated the heat coupling effect. The result confirmed that it is feasible to use the exothermic methanol conversion to enhance the endothermic transformation of some C5–C6 hydrocarbons into aromatic, resulting in a great engineering simplification of heat supply or heat removal in high temperature operation.

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