Petroleum Gas Oil-Ethanol Blends Used as Feeds: Increased Production of Ethylene and Propylene over Catalytic Steam-Cracking (CSC) Hybrid Catalysts. Different Behavior of Methanol in Blends with Petroleum Gas Oil

Hybrid catalysts that contain Zn Pd-based cocatalyst show a higher and more positive sensitivity to ethanol than catalysts that contain supported Ni-Ru cocatalyst. In fact, with the former catalysts, the use of gas oil-ethanol blends significantly increases the product yields of light olefins and particularly ethylene. This appears to be actually a good approach for the partial replacement of petroleum feedstocks by bioderived chemicals (particularly, bioethanol). Another advantage of the CSC process is that it can make use of simply concentrated ethanol in aqueous solution as obtained by enzymatic conversion of biomass. This is maybe the first example of the beneficial effect of bioethanol on the performance of the CSC catalysts, suggesting that the integration of a small biorefinery to a petrochemical production plant is now possible. On the other hand, over our hybrid catalysts methanol used as coreactant behaves very differently from ethanol. In fact, while ethanol undergoes predominantly dehydration into ethylene, methanol predominantly intervenes directly in the hydrocarbon pool, keeping the product propylene-to-ethylene ratio almost constant and higher than 1.5.