Activation of Pt Nanoclusters on TiO2 via Tuning the Metallic Sites to Promote Low-Temperature CO Oxidation

Kailin He,Qingyue Wang

doi:10.3390/catal11111280

Abstract

Metallic Pt sites are imperative in the CO oxidation reaction. Herein, we demonstrate the tuning of Pt sites by treating a Pt catalyst in various reductive atmospheres, influencing the catalyst activities in low-temperature CO oxidation. The H2 pretreatment of Pt clusters at 200 °C decreases the T50 from 208 °C to 183 °C in the 0.1 wt % Pt/TiO2 catalyst. The T50 shows a remarkable improvement using a CO pretreatment, which decreases the T50 further to 135 °C. A comprehensive characterization study reveals the integrated reasons behind this phenomenon: (i) the extent of PtO transition to metallic Pt sites, (ii) the ample surface active oxygen triggered by metallic Pt, (iii) the CO selectively adsorbs on metallic Pt sites which participate in low-temperature CO oxidation, and (iv) the formation of the unstable intermediate such as bicarbonate, contributes together to the enhanced activity of CO pretreated Pt/TiO2.

Highlights

Low-temperature CO oxidation is one of the most investigated model reactions in the field of heterogeneous catalysis [1]
Reduction pretreatment improved the catalytic performance of Pt/TiO2 in low-temperature oxidation by facilitating the formation of metallic Pt sites that can adsorb CO effectively
The unpretreated Pt/TiO2 with insufficient metallic Pt sites adsorbed CO on Pt2+, which participate in the oxidation reaction at elevated temperatures

Summary

Introduction

Low-temperature CO oxidation is one of the most investigated model reactions in the field of heterogeneous catalysis [1]. Oxidation reaction rates, and it is especially true for noble metal catalysts [7]. The linear CO adsorbed on metallic Pt sites that can facilely react with atmospheric O2 is responsible for the high activity in the low-temperature CO oxidation [8]. CO when the temperature is higher than 100 ◦ C. This required reduction pretreatment of Pt/TiO2 to obtain high activity in the low-temperature CO oxidation. The pretreatment conditions influence the peroxide and superoxide generated by O2 adsorption at the metal-support interface that determines the catalytic performance [9,10]

Methods

Discussion

Conclusion