Particle size effect of ZrO2 supports on catalytic liquid-phase oxidation of phenol over Pt/CeO2-ZrO2-Bi2O3/ZrO2 catalysts

Abstract

ABSTRACT The size effect of the ZrO2 support on the catalytic activity for the liquid-phase oxidation of phenol was demonstrated over Pt/CeO2-ZrO2-Bi2O3/ZrO2-X catalysts. Here, we selected six types of size-controlled ZrO2-X (X: A–F) (ZrO2-A: 35 nm, ZrO2-B: 22 nm, ZrO2-C: 14 nm, ZrO2-D: 11 nm, ZrO2-E: 9 nm, and ZrO2-F: 2 nm). The surface area of the ZrO2-X support was inversely proportional to the particle size of ZrO2. ZrO2-X (X: A–E) were crystalline phases, while ZrO2-F was amorphous phase. For Pt/CeO2-ZrO2-Bi2O3/ZrO2-X (X: A–E) catalysts, the smaller particle size of the crystalline ZrO2 (X: A–E) support resulted in a larger catalyst surface area, which in turn led to enhanced oxygen release and storage abilities of the CeO2-ZrO2-Bi2O3 promoter, and allowed for the oxidation of Pt0 to Pt2+ with high activity. The highest activity was obtained for the Pt/CeO2-ZrO2-Bi2O3/ZrO2-E catalyst, which had the largest surface area and the highest oxygen release and storage abilities; phenol was completely removed after a reaction time of 10 h at 80°C under atmospheric pressure (0.1 MPa).