2008 Volume 34 Issue 3 Pages 396-401
The conversion of bio-ethanol (ethanol: 77.4%, water: 19.6% and trace) derived from corn into hydrocarbons over HZSM-5 zeolites was studied. The reaction behaviors for formation of gaseous olefins and aromatics at WHSV=26 h−1 at 573–773 K were discussed by comparing with those of pure ethanol and 80% ethanol aqueous solution. The main products in the bio-ethanol conversion were ethylene or diethyl ether, and C3–C5 hydrocarbons and aromatics were also produced. The selectivity of olefins formation in C3–C4 hydrocarbons was depends on the reaction temperature. The yields of C3–C4 olefins increase with the rise of reaction temperature. The formation of them from bio-ethanol needs higher temperature than that from ethanol, and the decline of activity for bio-ethanol conversion was observed faster than that for a pure ethanol and an ethanol/water solution. The reason was explained by the strong acid site of HZSM-5 was poisoned by impurities in bio-ethanol such as sulfur. The content of aromatics was the largest at 648 K, but it decreased at 673 K. The order of amounts of aromatics produced were from pure ethanol>bio-ethanol>ethanol/water solution. The coexistence of water depressed the amount of aromatics, but the active sites changed by impurities in bio-ethanol promoted the formation of aromatics.
