Iron sulfide as a sustainable catalyst for the selective hydrogen transfer reduction for the synthesis of fine chemicals

Southouse, Jamie P.

Abstract

Platinum group metals have been the most widely applied metals for hydrogenation catalysts used in the synthesis of fine chemicals; this has been due to their high catalytic activity and ease of preparation. However, platinum group metal-based catalysts are often overly active in the synthesis of complex molecules with multiple susceptible groups present. The aim of the work in this thesis was to synthesise metal sulfide catalysts for the selective hydrogenation of nitroarenes that are free from platinum group metals.
In this work, a simple solvothermal synthesis method was developed to produce a wide range of first row transition metal sulfides. By simply changing the precursor metal salt, the metal sulfide could be precipitated. Additional modifications to the product sulfides were achieved by changing the temperature and capping agent, resulting in a synthesis method by which composition and crystal structure could be modified to produce a range of potential products. Optimisation test work was carried out on the synthesis of FeS2 pyrite and it’s characterisation by powder x-ray diffraction (PXRD) shows a single-phase product under the optimum conditions. Transmission electron microscopy (TEM) shows that the particles obtained are elongated with a width half that of their length which is between ca. 3-5 nm. The catalytic activity of these metal sulfides was characterised by their application in a heterogeneous hydrogen transfer reduction of substituted nitroarenes for the synthesis of substituted anilines. FeS2 pyrite showed excellent catalytic activity towards the hydrogen transfer reduction of nitroarenes. Reaction conditions for the hydrogen transfer reaction were optimised before testing other potential sulfide catalysts. NiS2 pyrite showed no catalytic activity when applied to the hydrogen transfer reaction. This was theorised to be due to the relatively small energy difference in Fe oxidation states allowing for chemical reactions to occur at low energy on the catalyst not present for Ni. FeS2 pyrite was applied to other substituted nitroarenes to determine the broad applicability of the catalyst. FeS2 pyrite maintained a high level of conversion of the substrate material with complete selectivity towards the aniline product. Other hydrogen donors are also explored.

Citation

Southouse, J. P. (2021). Iron sulfide as a sustainable catalyst for the selective hydrogen transfer reduction for the synthesis of fine chemicals. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4224438

• Thesis Type: Thesis
• Deposit Date: Nov 16, 2022
• Publicly Available Date: Feb 24, 2023
• Keywords: Chemical engineering
• Public URL: https://hull-repository.worktribe.com/output/4224438
• Additional Information: Department of Chemical Engineering, The University of Hull
• Award Date: Sep 1, 2021