Alumina microspheres for the adsorption of fatty alcohols containing oxygenates in Fischer-Tropsch synthetic oils

Abstract

The efficient and economical removal of oxygenated compounds from Fischer-Tropsch synthetic oil is vital to the promotion of high-quality chemical development in the coal chemical industry. In this study, alumina microspheres with high specific surface area, high pore capacity, and small particle size were prepared. The adsorption thermodynamics, adsorption kinetics, and column adsorption experiments were systematically conducted on various fatty alcohols bearing different carbon numbers, in mixtures of α-olefins and alkanes with different carbon numbers. The competitive adsorption behavior between weakly polar, oxide-containing methyl acetate and 12-alcohols on an alumina surface was investigated to better reduce the actual system. The Freundlich model exhibited a better fit than the Langmuir model. The adsorption kinetics and proposed first-order kinetic equations fitted better to the Crank model. Comparing the adsorption effect of commercial alumina and the alumina microspheres prepared in this study, it was observed that a smaller particle size and larger pore volume reduced the internal and external diffusion resistance of adsorption, and a larger specific surface area provided more adsorption sites for the adsorption of the oxide-containing compounds. The competitive adsorption behavior of fatty alcohols and methyl acetate on the surface of γ-alumina was explored using a combination of density functional theory (DFT) calculations and experimental techniques. The results of this study can prove to be extremely useful for the efficient removal of oxide-containing compounds from Fischer-Tropsch synthetic oils.