Photooxidation of Toluene: Correlation of Noble Metal Loading on Titania and Activation Energy

Haroon Ur Rashid,Muhammad Abid Zia,Saima Sadiq,M Sohail Ahmad,Rahmat Ali,Mohammad Sadiq,Razia Aman,Muhammad Humayun

doi:10.1155/2016/4231467

Abstract

A series of platinum and palladium supported on titania catalysts were prepared by wet impregnation method with the Pt or Pd loading varying in the range of 0.1–1.2 weight percent. The catalysts were characterized by SEM, EDX, XRF, XRD, FT-IR, and BET surface area analysis. The catalysts were tested for their efficiency in the liquid phase solvent-free photooxidation of toluene to benzyl alcohol and benzaldehyde in the presence of molecular oxygen. The effect of noble metal contents on the activation energy was studied. Activation energy was found to be in a reciprocal relation to the platinum or palladium content of the catalyst. The percent conversion of toluene was observed to increase in response to an increase in the metal loading on titania. The apparent quantum yield, however, was independent of the platinum or palladium content of the catalyst.

Highlights

Photocatalysis is based on the consumption of solar energy and has been extensively considered to be the approach of green chemistry
The photocatalytic activity of titania can be enhanced by incorporating metal ions
XRD reflections obtained for titania and metal supported on titania are presented in Figure 1, which shows the characteristic anatase peaks at 2θ = 25∘ and 48∘, and the observed pattern clarifies the absence of brookite and rutile phase of titania

Summary

Introduction

Photocatalysis is based on the consumption of solar energy and has been extensively considered to be the approach of green chemistry. There are many applications of titanium dioxide such as scratch-resistant optical coating paint pigments, which can show high activity to photooxidation reaction, in which the researchers are beginning to exploit the field [1]. TiO2 is a well-known and most applicable photocatalyst; it provides a best agreement between aqueous media and catalytic activity. 390 nm, titania can be activated by UV radiations. Photocatalytic reactions of TiO2 have attracted much attention of the researchers in the field of organic synthesis [6,7,8]. The photocatalytic activity of titania depends on its crystalline phase. The photocatalytic activity of titania can be enhanced by incorporating metal ions. A variety of methods such as precipitation, doping, and impregnation are used to introduce metal ions into titania [9,10,11]

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