“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

Abstract

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.

Mixed Naphtha/Methanol Feed Used in the Thermal Catalytic/Steam Cracking (TCSC) Process for the Production of Propylene and Ethylene

“…On the other hand, if methanol was used for the preparation of the mixed feeds, the ''ethylene ? propylene'' product yield increased with increasing methanol content, but gradually and at a much lower pace [15]. Also, very importantly, the product weight ratio ''propylene/ethylene'' remained almost constant at the value of the ''non-blended'' gas oil feed (i.e.…”

“…After activation at 750°C for 3 h, the solid material (called herein Y-AS) showed the following (approximate) chemical composition: 10 wt% Y 2 O 3 , with the balance being Al 2 O 3 [15,19]. Its surface did not show any acidity [20].…”

“…The Zn-Pd loaded co-catalyst was prepared in accordance with the procedure suggested by Dagle et al [21] and used in the previous work [15]. 4.00 g of zinc chloride (Aldrich) and 0.40 g of Pd (II) chloride (Aldrich) were dissolved in 30 mL of (warm) deionized water.…”

“…Recently, it was reported that hybrid catalysts developed for the TCSC process behaved very differently if a ''gas oilalcohol'' mixed feed was used [15]. If the alcohol was ethanol, there was a steady increase of the combined product yield ''ethylene ?…”

“…The feed used is petroleum light naphtha whose catalytic results are much easier to interpret than those of the gas oil as used in ref. 15. Several series of tests are performed on methanol added in various contents to light naphtha.…”