A catalytic conversion of ethanol to propylene was carried out using H-ZSM-11. The highest propylene selectivity was obtained at Si/Al2 ratio of 120 and the value was 25% at 0.1 MPa, 550 °C. In W-modified H-ZSM-11, the ethylene production by the dehydration of ethanol was promoted by higher W/Al2 ratio, whereas C4 formation by the oligomerization-cracking was slightly decreased with an increase in the W/Al2 ratio. When the W/Al2 ratio was 1.0, 23% and over of propylene selectivity was kept for over 16 h at 500 °C. A rapid increase in ethylene formation was also depressed. W-modified H-ZSM-11 with Si/Al2 ratio of 120 was found to be highly effective for the conversion of ethanol to propylene.
Metal modification effects on ethanol conversion to propylene were examined by use of H-ZSM-5 with Si/Al2 ratio of 150. In La- and Mg-co-modified H-ZSM-5 (La/Al2 ratio: 1.0, Mg/Al2 ratio: 0.10), 32% propylene selectivity was obtained at 0.1 MPa, 550 °C. This value was higher than those of unmodified and
La-modified (La/Al2 ratio: 1.0) H-ZSM-5. The number of acid sites and the acid strength (surface acidity) decreased in the order of unmodified,
La-modified, and La- and Mg-co-modified H-ZSM-5. In the initial stage of ethanol introduction, ethylene production by dehydration
of ethanol increased in La- and Mg-co-modified H-ZSM-5 with lower surface acidity, whereas the formation of aromatics by oligomerization-cracking
increased in unmodified H-ZSM-5 with higher surface acidity. The propylene selectivity was 25% after 36.2 h in the La- and
Mg-co-modified H-ZSM-5. The selectivity ratio of propylene to ethylene was 0.47 after 36.2 h; a rapid increase in ethylene
formation was also depressed. Therefore, La- and Mg-co-modified H-ZSM-5 with Si/Al2 ratio of 150 was highly effective for the conversion of ethanol to propylene.