Adding Value to Waste Minerals in a Circular Economy Framework: Ochre-Derived Layered Double Hydroxide Catalysts in Fatty Acid Ketonisation

Diego D Perera-Solis,Hugh Christopher Greenwell,Ella Fidment,Andrew Whiting,Matilda Pimlott

doi:10.3390/min9110681

Abstract

Transforming waste materials into added-value products is critical for a sustainable and circular economy. Here, Mg/Fe layered double hydroxide (LDH) materials, with a Mg2+:Fe3+ ratio of 2, were successfully synthesized via the co-precipitation method from a dissolved acid mine drainage precipitate waste “ochre”, which is normally put to landfill. The prepared LDH materials were tested as a heterogeneous base catalyst to promote the production of the ketone, 12-tricosanone, from lauric acid, a component of plant oils, through a ketonic decarboxylation reaction, giving a circular economy route to catalysts for sustainable ketone production. The highest yield of the ketone observed was 80%.

Highlights

IntroductionSignificant research has been undertaken working towards routes to produce bio-derived synthons that otherwise would be produced by traditional petroleum-derived routes [4,5,6]
Treatment and reuse of waste is an important component of the emerging circular economy, where waste reduction and valorisation is needed to address the increasing population and the associated increasing consumer demand, which directly drives an increase in the consumption of goods, energy and the depletion of natural resources with associated increased waste to dispose of [1]
In our previous study [10], we explored and tested the heterogeneous base catalytic activity of layered double hydroxides (LDHs) to promote the formation of ketones from carboxylic acids through the ketonic decarboxylation reaction

Summary

Introduction

Significant research has been undertaken working towards routes to produce bio-derived synthons that otherwise would be produced by traditional petroleum-derived routes [4,5,6]. The base catalysed production of ketones from plant oil-derived fatty (and other carboxylic) acids has become an important reaction for the production of bio-based lubricants, fuel blends and detergents, as well as a mechanism to reduce the oxygen content within pyrolysis oil from biomass [3,7,8,9]. In our previous study [10], we explored and tested the heterogeneous base catalytic activity of layered double hydroxides (LDHs) to promote the formation of ketones from carboxylic acids through the ketonic decarboxylation reaction. Ketones are normally produced through oxidation of petroleum hydrocarbons, whereas ketonic decarboxylation is a deoxygenation reaction in which two carboxylic

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