Dielectric barrier discharge plasma synthesis of Ag/γ-Al2O3 catalysts for catalytic oxidation of CO

Abstract

In this study, Ag/γ-Al2O3 catalysts were synthesized by an Ar dielectric barrier discharge plasma using silver nitrate as the Ag source and γ-alumina (γ-Al2O3) as the support. It is revealed that plasma can reduce silver ions to generate crystalline silver nanoparticles (AgNPs) of good dispersion and uniformity on the alumina surface, leading to the formation of Ag/γ-Al2O3 catalysts in a green manner without traditional chemical reductants. Ag/γ-Al2O3 exhibited good catalytic activity and stability in CO oxidation reactions, and the activity increased with increase in the Ag content. For catalysts with more than 2 wt% Ag, 100% CO conversion can be achieved at 300 °C. The catalytic activity of the Ag/γ-Al2O3 catalysts is also closely related to the size of the γ-alumina, where Ag/nano-γ-Al2O3 catalysts demonstrate better performance than Ag/micro-γ-Al2O3 catalysts with the same Ag content. In addition, the catalytic properties of plasma-generated Ag/nano-γ-Al2O3 (Ag/γ-Al2O3-P) catalysts were compared with those of Ag/nano-γ-Al2O3 catalysts prepared by the traditional calcination approach (Ag/γ-Al2O3-C), with the plasma-generated samples demonstrating better overall performance. This simple, rapid and green plasma process is considered to be applicable for the synthesis of diverse noble metal-based catalysts.