Sustainable formation of tricarballylic acid from citric acid over highly stable Pd/Nb2O5.nH2O catalysts

Recently, a reaction sequence was developed for the production of tricarballylic acid, an interesting plasticiser precursor, from citric acid by using a H-Beta zeolite and Pd/C catalyst. Although yields of 85% of tricarballylic acid were obtained, citric acid elicited Al leaching from the zeolite framework, resulting in loss of activity. In this work, Nb2O5.nH(2)O was found to be a stable and performant catalyst for this reaction, and a strong involvement of the hydroxyl group of citric acid with the Nb2O5.nH(2)O surface was observed by C-13 MAS NMR. Next, Pd/Nb2O5.nH(2)O catalysts were synthesized via a low temperature reduction method to preserve the acidity of the Nb2O5.nH(2)O support; the nature of the Pd phase was examined by XAS. In presence of a 0.6 wt% Pd/Nb2O5.nH(2)O catalyst, yields over 90% of tricarballylic acid were obtained over multiple runs. Finally, this catalyst was also suitable for the dehydration-hydrogenation of other monohydroxy carboxylic acids. (C)& nbsp;2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, a stable and performant catalyst, Nb2O5.nH(2)O, was found for the production of tricarballylic acid from citric acid. By synthesizing Pd/Nb2O5.nH(2)O catalysts and preserving the acidity of the support using a low temperature reduction method, high yields of tricarballylic acid were obtained. The catalyst also showed suitability for the dehydration-hydrogenation of other monohydroxy carboxylic acids.