Efficient treatment of crude oil-contaminated hydrodesulphurization catalyst by using surfactant/solvent mixture

The purpose of this work is to investigate desorption efficiency for regenerating a crude oil-contaminated catalyst by using an ex-situ surfactant/solvent washing technique. We employed six types of surfactants and solvents for optimization, and established an optimal mixture of surfactant and solvent for the removal of crude oil from the contaminated catalyst. The efficiency of the surfactant/solvent mixture for the removal of crude oil from the contaminated catalyst was determined based on the mass ratio of surfactant to solvent, contact time, pH, and temperature. The raw catalyst, crude oil-contaminated catalyst, and after washing catalyst were characterized by interracial rheometer, zeta-potential analyzer, and scanning electron microscope. We found that the Brij-58/1,2-dimethylbenzene mixture could provide superior crude oil removal efficiency. At a higher mass ratio of 1,2-dimethylbenzene, the crude oil removal rate of the contaminated catalyst exceeds 95%. This result is attributed to the addition of the solvent to the surfactant solution. The solvent can significantly decrease the surfactant's CMC and increase the micelle's number, thereby enhancing the mixture's washing efficiency. Since aromatic solvents and crude oil components have similar structures in terms of polarity and aromaticity, the Brij-58/1,2-dimethylbenzene mixed system has a strong affinity for crude oil components.