Investigation of the Effect of Alumina Binder Addition to Pd/SO42––ZrO2 Catalysts during Sol–Gel Synthesis

Abstract

We have incorporated alumina into palladium catalysts supported on sulfated zirconia (Pd/SZ) during sol–gel synthesis for application in a washcoat for NOx emissions control in natural gas-fired lean-burn engines. In situ incorporation of the adhesivity-enhancing “binder”, alumina, during the sol–gel synthesis of the Pd/SZ catalyst demonstrated significantly improved NOx reduction activity of the previously reported dual-catalyst bed when compared to the conventional ex situ mode of binder addition in a slurry. The effects of alumina addition during sol–gel synthesis of Pd/SZ on the structural, textural, and chemical properties of the resulting catalyst were examined in this study. The evolution of the crystal phase of zirconia during calcination of the Pd/SZ catalyst with the binder incorporated during the sol–gel process was studied using in situ XRD during calcination under air. Comparison of the crystal phase composition of the binder-free and binder-incorporated samples calcined at 700 and 900 °C dem...