Abstract
We propose a novel method to upgrade heavy oil. This method utilizes dealkylation of alkyl polycyclic aromatic hydrocarbons on a silica monolayer solid acid catalyst to produce alkanes with preserved alkyl chain length and aromatic hydrocarbons without alkyl groups, resulting in maximization of the yields of value-added products, alkanes suitable for diesel fuel and alkylbenzenes suitable for gasoline and chemical feedstocks. Basic compounds in vacuum gas oil were found to inhibit the reaction, but were removed by treatment with solid acids such as strongly acidic cation exchange resin and amorphous silica_alumina. Drying of the silica_alumina significantly enhanced the removal rate. The silica_alumina was repeatedly usable by calcination in an oxygen flow. After the treatments for the removal of basic compounds, dealkylation of alkyl polycyclic aromatic hydrocarbons proceeded at 673 K. However, rapid catalyst deactivation was observed. Higher reaction temperature of 723 K suppressed deactivation of the catalyst and maintained the high selectivity. Even in the optimized conditions, slow deactivation of the catalyst was observed, but the catalyst was regenerated by calcination at 773 K in oxygen, and the catalytic performance was repeatedly demonstrated.
