Synthesis of nanoscale CuO via precursor method and its application in the catalytic epoxidation of styrene.

Ruhul Amin Bepari,Palash Bharali,Birinchi Kumar Das

doi:10.1039/d1ra09384c

Abstract

Nanoscale CuO with diameters in the range of 7–8 nm has been synthesized via a two-step precipitation–calcination method using copper(ii) isonicotinate tetrahydrate as the precursor. The first step involves the room temperature stirring of an alkaline ethanolic solution of the precursor which gives a non-crystalline CuO species, while the second step involves the calcination of the product of the first step at 180 °C to form nanocrystalline CuO which has been characterized by PXRD, TEM, SEM, H2-TPR and Raman spectroscopy, etc. The CuO material has shown excellent catalytic activity in the oxidation of styrene using TBHP as the oxidizing agent leading to complete styrene conversion with more than 95% styrene oxide selectivity at the end of 6 h. The oxide catalyst can be reused for at least 6 successive runs without significant loss in activity.

Highlights

Amongst the transition metals, copper nds numerous applications in diverse elds ranging from catalysis to drug delivery systems
Transmission electron microscopy (TEM) images were recorded on two different high resolution transmission electron microscopes (HRTEM) viz. HRTEM, JEOL, model 1200 EX operating at 100 kV and TEM, JEM-2100, JEOL operating at 200 kV
Temperature-programmed reduction (TPR) experiments were performed using a Micromeritics AutoChem 2910 analyzer equipped with a thermal conductivity detector (TCD)

Summary

Introduction

Copper nds numerous applications in diverse elds ranging from catalysis to drug delivery systems. Currently researchers are exploring properties both of the elemental copper as well as its compounds for various applications. The synergistic catalytic effect of the Se–Cu system has recently been used to produce aketoacetals by the activation of a-H of methyl ketones with molecular oxygen.[1] In another instance, the synergistic catalytic activity of the Se–Cu catalyst has been reported for the diethoxylation of halomethylene ketones using molecular oxygen as the green oxidant.[2] Recently, Lei et al have reported the high catalytic turnover numbers in the Buchwald–Hartwig coupling reaction of pyrimidin-2-amines over the polyanilinesupported copper catalyst (Cu@PANI) which was synthesized via the oxidative polymerization of aniline.[3] Likewise, the oxides of copper, the cupric oxide (CuO), have attracted signi cant research interests in the recent years This p-type semiconductor material with narrow band gap (1.7) eV nds important use in light emission,[4] catalysis,[5] gas-sensing,[6] solar-energy harvesting,[6,7] superconductivity and magnetoresistivity applications.[3,7] Nanoscale CuO with various morphologies was successfully fabricated by several methods.[4,5,6,7,8,9,10,11,12] In the recent times, researchers have been attracted towards the new trend of synthesizing copper oxide

Methods

Results

Conclusion