MOF Embedded and Cu Doped CeO2 Nanostructures as Efficient Catalyst for Adipic Acid Production: Green Catalysis

Shabahat Bibi,Erum Pervaiz,Minghui Yang,Osama Rabi

doi:10.3390/catal11030304

Abstract

Greatly efficient chemical processes are customarily based upon a catalyst activating the process pathway to achieve higher yields of a product with desired specifications. Catalysts capable of achieving good performance without compromising green credentials are a pre-requisite for the development of a sustainable process. In this study, CeO2 nanoparticles were tested for their catalytic activity with two different configurations, one as a hybrid of CeO2 nanoparticles with Zeolitic Immidazole Framework (ZIF-67) and second being doped Cu cations into CeO2 nanoparticles. Physicochemical and catalytic activity was investigated and compared for both systems. Each hybrid was synthesized by embedding the CeO2 nanoparticles into the microporous structure of ZIF-67, and Cu doped CeO2 nanoparticles were prepared by a facile hydrothermal route. As a catalytic test, it was employed for the oxidation of cyclohexene to adipic acid (AA) as an alternative to expensive noble metal-based catalysts. Heterogeneous ZIF-67/CeO2 found catalytical activity towards the oxidation of cyclohexene with nearly complete conversion of cyclohexene into AA under moderate and co-catalyst free reaction conditions, whereas Cu doped CeO2 nanoparticles have shown no catalytic activity towards cyclohexene conversion, depicting the advantages of the porous ZIF-67 structure and its synergistic effect with CeO2 nanoparticles. The large surface area catalyst could be a viable option for the green synthesis of many other chemicals.

Highlights

Catalysis, which is defined as speeding up of a chemical reaction through a substance that is not consumed itself, is critically important for all areas of modern-day life
The catalytic activity of CeO2 nanoparticles has been evaluated with two different formulations: one was embedded into metal organic framework (MOF) (ZIF-67) and the second with
This very facile and cost-effective approach was adopted to synthesize a hybrid structure of pure phase CeO2 nanoparticles encapsulated inside

Summary

Introduction

Catalysis, which is defined as speeding up of a chemical reaction through a substance that is not consumed itself, is critically important for all areas of modern-day life. CeO2 nanocrystalline particles are interesting because of their diverse area of applications in the fields of catalysis, fuel cells, UV absorbance, electronics, and biomedicine [1–6] This is because CeO2 has excellent properties of shuffling between the valence states of 4+ and 3+ , generating oxygen vacant defects, and high oxygen storage capability [7–9] In general, the catalytical activity and reducibility of CeO2 depends on its surface oxygen content, increasing the concentration of accumulated active oxygen on the surface of CeO2 would result in its higher catalytic activity. This, increased the specific surface area of CeO2 and resulted in better redox characteristics [14,15]

Methods

Results

Conclusion