Structural and Acidity Studies of Sulphated Zirconia Catalyst Prepared from Solid Sulphates by Environmental Friendly Method

Abstract

Non-crystalline sulphated zirconia catalysts were synthesised by a non-aqueous and non-conventional method. The effect of varying the ratio of sulphating agent to zirconium source was also investigated. The samples were characterized by X-ray diffraction, Energy Dispersive X-ray (EDX), Infra red Spectroscopy (IR), X-ray Photoelectron Spectroscopy (XPS). The surface acidity was measured by the Pyridine-DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) technique. The structural and textural properties of the sulphated zirconias were studied. The EDX and XPS profiles suggested that both sulphated zirconia catalysts have similar zirconia and sulphate structures; however, both catalysts were amorphous. The deconvoluted spectra of oxygen 1s confirmed the presence of oxide oxygen of zirconium and sulphate oxygen on the catalysts. Sample I had a higher amount of sulphate oxygen than sample II. Adsorption of pyridine into both samples indicated higher amounts of Brönsted acid sites in sample I, although, lower amount of sulphate was used during preparation. This opens up the possibility of controlling the degree and type of active sites on a catalyst by the amount of sulphate used for preparation.