Dominant roles of total acidity and sulfates density determining sulfated zirconia catalyst efficiency

Abstract

Sulfated zirconia catalysts are obtained from sulfated hydroxide, hydroxide and nitrate by the appropriate methods. Differences in properties of precursors and the applied calcination temperature induce various content of residual sulfate after calcinations considerably influencing total acidity of samples. Activity and selectivity of the catalysts are complex synergistic functions of the content of sulfates and related surface properties accompanying with the fraction of the tetragonal crystal phase, where total acidity and density of sulfates act as dominant factors. The best catalytic performances obtained in the case of the application of the catalysts originated from commercial sulfated zirconium-hydroxide and zirconium-oxynitrate were reached at the highest reaction temperature of 350°C previously calcined at the lowest calcination temperature of 500°C in the preparation procedure. The catalyst obtained from zirconiumhydroxide is characterized with the lowest amount of residual sulfates, thus resulted in inferior surface characteristics; consequently, its activity is the poorest.