Chemoselective hydrogenation of nitroarenes over supported pt nanoparticles

Xiao, Lifeng 2023. Chemoselective hydrogenation of nitroarenes over supported pt nanoparticles. PhD Thesis, Cardiff University. Item availability restricted.

	PDF - Accepted Post-Print Version Restricted to Repository staff only until 17 June 2025 due to copyright restrictions. Download (6MB)
	PDF (Cardiff University Electronic Publication Form) - Supplemental Material Restricted to Repository staff only Download (126kB)

Abstract

Selective hydrogenation of nitroarenes, crucial in synthesizing functionalized anilines for pharmaceuticals, and fine chemicals, is a key focus in industrial and academic research. The challenge is to control the chemoselectivity during the hydrogenation of nitro group in nitroaromatics, particularly in the presence of other reducible groups like C=O, C=C, and C≡C. Thus, designing a heterogenous catalyst with a high chemoselectivity is of great significance. In this regard, this thesis aims to derive a fundamental understanding of the relationship between chemoselectivity and the active sites of heterogeneous catalysts and thereby design a catalyst that has very high chemoselectivity. Recent advancements in tuning the structure and properties of supported metal nanoparticles and single atoms such as particle size and metal -support interaction have led to the development of several heterogeneous catalysts for the chemoselective hydrogenation of nitroarenes. Pt-based nanoparticles, known for high catalytic activity, often lack selectivity towards specific functional groups. Herein, we report the support-induced chemoselectivity (SIC) switching between nitro and vinyl group during the hydrogenation of 3-nitrostyrene (3-NS) over supported Pt nanoparticles. The Pt/TiO2 and Pt/Nb2O5 catalyst with a reversed chemoselectivity was further studied by kinetic experiment and extensive characterization using STEM, XPS, CO-DRIFTS, and so on, along with in situ DRIFTS studies, were conducted to understand the 3-nitrostyrene adsorption over catalysts. DFT methods were employed to identify the nature of active sites and explain the observed SIC between Pt/TiO2 and Pt/Nb2O5 catalysts. It was found the electronic structure at the metal-support interfacial sites played a key role in tuning the chemoselectivity during 3-NS hydrogenation. This was further confirmed by the selective blocking of the Ptsupport interfacial sites. It indicated the Pt-Pt terrace site was attributed to the -C=C chemoselective hydrogenation and the interfacial site of Pt and TiO2 was attributed to the -NO2 chemoselective hydrogenation. In the end, the effect of Pt particle size on the chemoselectivity was also studied.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	17 June 2024
Last Modified:	17 Jun 2024 13:21
URI:	https://orca.cardiff.ac.uk/id/eprint/169848

Actions (repository staff only)

Edit Item