ESR study of paramagnetic sites in sulfated zirconia

ESR spectroscopy was used to investigate paramagnetic sites in sulfated zirconia. Catalysts derived from zirconium oxide and zirconium hydroxide were studied. It was demonstrated that paramagnetic sites assigned to near-surface F-centers were formed during activation at temperatures above 573 K. The catalyst derived from zirconium hydroxide shows after activation at 873 K two types of paramagnetic sites: F-centers and Zr3+ sites. Both F-centers and Zr3+ sites in this catalyst form complexes with reagents upon n-butane or hydrogen adsorption at range of 423–523 K in contrast to paramagnetic sites of the oxide-derived catalyst.