Adsorption mechanism of phosphorus on alumina

The effect of phosphorus on the acidity and physical properties of a support of γ-alumina was studied, as a preliminary stage to understanding its role as an additive in hydrotreatment catalysts. The results showed that phosphorus was adsorbed on alumina following a Langmuir-type mechanism, in which a phosphate ion monolayer was formed at the surface. Equilibrium was strongly displaced towards adsorption. These results were verified using X-ray photoelectron spectroscopy. Phosphorus modified not only the acidity but also the physical properties of the alumina. From the experimental results obtained, an adsorption mechanism of phosphorus on alumina could be established.