Textural properties of sulfated iron hydroxide promoted with aluminum

Abstract  Aluminum-promoted sulfated iron hydroxide samples were prepared by a coprecipitation method with different loading levels of Al^III followed by sulfation and calcination at 870 K. These samples were characterized by means of thermal gravimetric analysis, X-ray powder diffraction, nitrogen adsorption at 77 K, diffuse reflectance spectroscopy, and FT-IR spectroscopy using KBr pellets. TGA profiles showed sulfated species with different thermal stabilities in the samples, and incorporation of Al^III causes an increase in the thermal stability of the surface sulfate species. The presence of sulfate ions and Al^III promotion did not modify the crystal phase of α-Fe₂O₃, but it did increase the crystallite size. A textural study showed that the incorporation of Al^III into the sulfated samples led to diminished surface area and pore volume. The pore size distribution exhibited a wide spectrum of mesoporosity in all samples. Graphical Abstract