Effect of Nanoparticle Size in Pt/SiO2 Catalyzed Nitrate Reduction in Liquid Phase

Khawer Shafqat,Minna Tiainen,Riitta L Keiski,Lenka Matějová,Satu Pitkäaho

doi:10.3390/nano11010195

Khawer Shafqat, Minna Tiainen + Show 3 more

Open Access

https://doi.org/10.3390/nano11010195

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Abstract

Effect of platinum nanoparticle size on catalytic reduction of nitrate in liquid phase was examined under ambient conditions by using hydrogen as a reducing agent. For the size effect study, Pt nanoparticles with sizes of 2, 4 and 8 nm were loaded silica support. TEM images of Pt nanoparticles showed that homogeneous morphologies as well as narrow size distributions were achieved during the preparation. All three catalysts showed high activity and were able to reduce nitrate below the recommended limit of 50 mg/L in drinking water. The highest catalytic activity was seen with 8 nm platinum; however, the product selectivity for N2 was highest with 4 nm platinum. In addition, the possibility of PVP capping agent acting as a promoter in the reaction is highlighted.

Highlights

Platinum (Pt) is an important catalyst in environmental applications
The resulting nanoparticles were precipitated with 40 mL acetone and centrifuged
For the size effect study, synthesized Pt NPs were supported on two different types of silica (SiO2 )

Summary

Introduction

Platinum (Pt) is an important catalyst in environmental applications. The recent advances in nanoparticle synthesis offer new possibilities for utilizing this precious metal even more atom-efficiently in the future [1]. Platinum catalysts are considered very effective in various hydrogenation reactions for fundamental research and industrial applications [7]; most studies are carried out in gas phase [3]. It is worth examining the size effect of platinum nanoparticles at the solid–liquid interface, and we chose to study nitrate (NO3− ) reduction in aqueous phase. Hydrogenation in liquid phase by using size-controlled supported Pt monometallic catalyst has not been studied yet These facts indicate that there still exists a lack of knowledge how to make/prepare a monometallic catalyst to be an efficient and cheaper catalyst (compared to bimetallic catalysts) for the reduction of nitrate (NO3− ). The effect of nanoparticle size on catalytic activity was studied in nitrate reduction in an aqueous phase

Catalyst Preparation

Characterization

Activity Experiments

Characterization of the Prepared Catalysts

Influence of Pt Nanoparticle Size on Activity in Nitrate Reduction

Conclusions