Recovery/Reuse of Heterogeneous Supported Spent Catalysts

Mariachiara Miceli,Angela Malara,Anastasia Macario,Patrizia Frontera

doi:10.3390/catal11050591

Mariachiara Miceli, Angela Malara + Show 2 more

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https://doi.org/10.3390/catal11050591

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Abstract

The rapid separation and efficient recycling of catalysts after a catalytic reaction are considered important requirements along with the high catalytic performances. In this view, although heterogeneous catalysis is generally less efficient if compared to the homogeneous type, it is generally preferred since it benefits from the easy recovery of the catalyst. Recycling of heterogeneous catalysts using traditional methods of separation such as extraction, filtration, vacuum distillation, or centrifugation is tedious and time-consuming. They are uneconomic processes and, hence, they cannot be carried out in the industrial scale. For these limitations, today, the research is devoted to the development of new methods that allow a good separation and recycling of catalysts. The separation process should follow a procedure economically and technically feasible with a minimal loss of the solid catalyst. The aim of this work is to provide an overview about the current trends in the methods of separation/recycling used in the heterogeneous catalysis.

Highlights

Catalysts represent a key component in a broad range of reactions, being generally characterized by high activity and selectivity
Carbon based materials are generally used as support materials for the dispersion of active components in many catalytic processes [17,18,19,20,21] because of their high specific surface, good physical and thermal stability, reusability, and regeneration capacity. Their easiness of recycling offers the opportunity to increase the use of expensive catalysts based on noble metals since the organic content of the spent catalyst can be destroyed by a simple combustion process under mild conditions
Precipitation, distillation, and ion exchange are other separation procedures used as an alternative to solvent extraction [86,87]

Summary

Introduction

Catalysts represent a key component in a broad range of reactions, being generally characterized by high activity and selectivity. Carbon based materials (e.g., graphene, activated carbon, biochar) are generally used as support materials for the dispersion of active components in many catalytic processes [17,18,19,20,21] because of their high specific surface, good physical and thermal stability, reusability, and regeneration capacity. Their easiness of recycling offers the opportunity to increase the use of expensive catalysts based on noble metals since the organic content of the spent catalyst can be destroyed by a simple combustion process under mild conditions. This leads to highly concentrated ashes from which an easy and economical recovery of precious metals is possible [22]

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Conclusion