Variations to a bio-electrochemical nitro-reduction catalyst for the production of amines

Thesis

This thesis aims to unite materials and catalysis research to establish new directions for a biocatalytic nitro-reduction system developed by the Vincent group, consisting of hydrogenase enzyme immobilised on conductive carbon particles. In this system, the nitro-group can be reduced on the carbon surface using the electrons provided by the hydrogenase through H2 oxidation. In the first part of the thesis, the carbon support is varied while the second part of the thesis focuses on replacing the enzyme with a synthetic H2 oxidation catalyst.

In the first part, a set of nitrogen-doped carbon nanotubes (NCNTs), along with comparable pristine CNTs, are synthesized through chemical vapour deposition and their nitro-reduction activity is electrochemically assessed. The NCNTs lead to the nitro-reduction occurring at a significantly milder potential as opposed to the CNTs or any other trialled carbon-based electrode material. This electrocatalytic effect is then used to both electrosynthesize amines using milder conditions and to tune the hydrogenase-on-carbon (Hyd/C) catalyst system to hydrogenate more difficult to reduce nitro-groups.

In the second part of the thesis, an established Ni-based biomimetic H2-oxidation catalyst is employed. The complex on carbon constitutes a highly selective, active, and recyclable catalyst system for the production of amines from nitro-groups in aqueous media, room temperature, and at atmospheric H2 pressure. Interestingly, the complex in solution is found to catalyse the clean synthesis of the partially reduced product, hydroxylamine. 

Authors: Landis, MA

• DOI: 10.5287/ora-14dpxxyzr
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Subjects: Electrodes, Carbon; Bioelectrochemistry