Stable metal organic frameworks for the catalytic destruction of chemical warfare agents

  • Caroline Elliott

Student thesis: Doctoral Thesis (PhD)

Abstract

The work described within this Thesis has focused on the preparation and characterisation of metal-organic frameworks (MOFs) as catalysts for the hydrolysis of the nerve agent simulant dimethyl 4-nitrophenyl phosphate (DMNP).

Mixed-metal MOFs were explored for this application using a combination of zirconium and hafnium in known MOFs in order to investigate the role of Lewis-acidity on catalysis. A series of mixed-metal MOFs were prepared and successfully catalysed the hydrolysis of DMNP. For UiO-66 and NU-1000 the highest rates were seen for the Zr 100% samples. For MOF-808 the most successful catalyst was found to be the Zr 33% Hf 66% sample. Further investigations compared properties of each sample and concluded that a change in Lewis-acidity plays a role in the catalytic activity, despite differences in material characteristics.

Mixed-linker MOFs were also investigated through the addition of di-topic linkers to a MOF-808 synthesis. For each sample, ca. 10\% of a chosen di-topic linker, as a proportion of linker present, was incorporated into the MOF-808 structure. Further investigations using the 5-amino isophthalic acid di-topic linker found up to 25% of 5-amino isophthalic acid could be incorporated into MOF-808. All samples successfully hydrolysed DMNP, with the 20% 5-amino isophthalic acid MOF-808 sample giving the highest rate and out-performing the parent MOF-808 sample.

Investigations into preparing MOF-composite materials were also carried out. This focused on incorporating MOF-808 into the materials PET, cotton, silk and nylon, using a range of synthesis methods. Loading estimates were calculated through q-NMR measurements. All materials saw MOF-808 successfully deposited on the surface, with the exception of one sample. All materials tested as catalysts for the hydrolysis of DMNP outperformed the blank samples. MOF-808 had therefore retained catalytic properties within the composite material. The hydrothermal synthesis method using PET displayed the highest initial rate for all composite materials prepared.
Date of Award29 Nov 2023
Original languageEnglish
Awarding Institution
  • University of St Andrews
SupervisorRussell Edward Morris (Supervisor)

Keywords

  • MOF
  • Chemical warfare agents
  • Zirconium
  • Hafnium
  • Composite materials

Access Status

  • Full text open

Cite this

'