Issue 19, 2017

Stabilising Ni catalysts for the dehydration–decarboxylation–hydrogenation of citric acid to methylsuccinic acid

Abstract

A new reaction sequence of dehydration–decarboxylation–hydrogenation to transform citric acid into methylsuccinic acid has recently been developed using Pd as a noble metal catalyst in water. In this work Ni catalysts were investigated as low cost, non-noble metal alternatives. Several home-made and commercial catalysts were screened for this reaction. Citric acid was very reactive and full conversions were readily obtained in all cases. However, the selectivity to methylsuccinic acid was initially low, since typical Ni catalysts were not stable and therefore not able to hydrogenate the formed C[double bond, length as m-dash]C double bonds. Due to the lower hydrogenation activity of Ni compared to Pd, new side products appeared. Particularly, hydration of the C[double bond, length as m-dash]C double bonds made the reaction network more complex in this case. Fortunately, the formation of all hydration products – even the rather stable lactone, β-carboxy-γ-butyrolactone – was eventually shown to be completely reversible. Three routes were then studied to stabilise Ni catalysts and to enable the Ni catalyzed conversion of citric acid to methylsuccinic acid; partial neutralisation of the acid reactant, adding Fe to Ni/ZrO2 or to the reaction mixture and coating Ni particles with carbon, all proved to stabilise Ni and all resulted in high to very high methylsuccinic acid yields. Furthermore, the role of Fe was unravelled by performing reference reactions with different Fe compounds and by in depth characterisation of the NiFe/ZrO2 catalyst. Finally, the reaction conditions were optimised using the carbon-coated Ni nanoparticles and kinetic profiles were recorded to confirm the extended reaction network.

Graphical abstract: Stabilising Ni catalysts for the dehydration–decarboxylation–hydrogenation of citric acid to methylsuccinic acid

Supplementary files

Article information

Article type
Paper
Submitted
15 Чер 2017
Accepted
25 Сер 2017
First published
25 Сер 2017

Green Chem., 2017,19, 4642-4650

Stabilising Ni catalysts for the dehydration–decarboxylation–hydrogenation of citric acid to methylsuccinic acid

J. Verduyckt, A. Geers, B. Claes, S. Eyley, C. Van Goethem, I. Stassen, S. Smolders, R. Ameloot, I. Vankelecom, W. Thielemans and D. E. De Vos, Green Chem., 2017, 19, 4642 DOI: 10.1039/C7GC01773A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements