Alkylation of Asphaltenes Using a FeCl₃Catalyst

Abstract

Friedel−Crafts alkylation as a strategy to convert asphaltenes to maltenes was investigated. It was postulated that conversion of polar hydroxyl groups in the asphaltenes would make the product more soluble in light hydrocarbons. Reactions were performed with oilsands bitumen-derived materials using FeCl 3 as a catalyst and o-xylene and methanol, separately. Only the reaction of o-xylene with asphaltenes was mildly beneficial; it resulted in 6% conversion of asphaltenes to maltenes and an increase of 9% in straight-run distillate and vacuum gas oil. The reactions of o-xylene with maltenes and bitumen were detrimental, as was all alkylation reactions with methanol. To better understand the nature of the conversion, the reactions were repeated with model compounds. With 2-naphthol, it was found that dimerization of 2-naphthol to produce (1,1′-binaphthalene)-2,2′-diol (BINOL) and the subsequent coordination with iron were the two dominant reactions. The adverse consequences of FeCl 3 -catalyzed conversion could be explained by such intermolecular addition reactions. The reaction of 2-naphthol with methanol and FeCl 3 also caused some chlorination of the product. The possibility that FeCl 3 as a catalyst affected ethers was explored by performing the reaction with dibenzyl ether as feed. It was found that the ether bonds were cleaved. In the presence of o-xylene, ether cleavage was followed by C-alkylation. The increase in maltenes after the reaction of o-xylene with asphaltenes was better explained by C-alkylation following ether cleavage than the reaction between o-xylene and the hydroxyl groups in the asphaltenes. The reaction of dibenzyl ether with methanol produced benzaldehyde, rearrangement products, and heavy gums.

Integration of Fischer–Tropsch and Oilsands Bitumen Production Processes

“…It is likely that the alcohols would be reactive. At moderate reaction temperatures, no benefit was found when using methanol for Friedel–Crafts alkylation of oilsands derived materials with FeCl 3 , but this might have been due to the catalyst, rather than the potential benefit of reacting alcohols with bitumen . In other work, some hydrolysis was noted, and with a more appropriate choice of catalyst, the alcohol-rich material might assist in bitumen upgrading through addition reactions.…”

“…At moderate reaction temperatures, no benefit was found when using methanol for Friedel−Crafts alkylation of oilsands derived materials with FeCl 3 , but this might have been due to the catalyst, rather than the potential benefit of reacting alcohols with bitumen. 35 In other work, some hydrolysis was noted, 28 and with a more appropriate choice of catalyst, the alcohol-rich material might assist in bitumen upgrading through addition reactions. The alcohols could also be used in conjunction with the water employed for bitumen recovery, or during bitumen liberation and separation to change the water properties, such as suggested by Cobb.…”