The Balance Between Reactivity and Stability of Modified Oxide Surfaces Illustrated by the Behavior of Sulfated Zirconia Catalysts

Abstract

The stability of a series of sulfated zirconia catalysts, promoted with up to 2 wt% iron or manganese, in their calcined state was investigated. Phase composition, nature of surface sulfate species, degree of hydroxylation, and butane isomerization activity changed duri ng aging over months in various atmospheres and during milling. The metastability of small oxide particles is discussed, including literature data on alumina, titania and other oxides. Catalytically active fractions of a material easily transition into more stable, less active forms.

Sulfate Grafted Iron Stabilized Zirconia Nanoparticles as Efficient Heterogenous Catalysts for Solvent-Free Synthesis of Xanthenediones under Microwave Irradiation

“…It has been observed that the sulfated zirconia catalyst undergoes phase transformation upon thermal or mechanical treatment or adsorption of water, resulting in loss of activity. The presence of Fe and Mn as promoters stabilizes the tetragonal phase, making promoted catalysts much more stable during storage or treatment …”