Ethylene reaction at high temperatures on HZSM-5

The catalytic cracking of ethylene was investigated at 973 K and 873 K, at atmospheric pressure and in presence of a weakly dehydroxylated (WD), or strongly dehydroxylated (SD), HZSM-5. At 873 K the catalytic activity of the WD sample is very small, whereas the one for the SO sample is significant However, at 973 K a significant amount of ethane was produced by the SD sample, whereas benzene was the main product for the WD zeolite. A very rich and wide hydrocarbon product distribution was observed for the WD sample and its catalytic activity was stable, even after a long time on stream. A difference in product selectivity for the two catalysts was also observed. Since the surface areas of both catalysts strongly decreased during reaction, due to the formation of carbonaceous species, whose catalytic activity is still significant, it demonstrates that those species play an active role on the ethylene reaction, probably acting as a proton source. The catalysts were also characterised by BET, XRD, SEM and by an Induction Furnace. Our results also show that the carbonaceous species formed on both spent catalysts are amorphous in nature, the carbon content is high and the morphology is different.