Acetylene hydrochlorination using Au supported on activated carbon catalysts

Lazaridou, Anna 2023. Acetylene hydrochlorination using Au supported on activated carbon catalysts. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Acetylene hydrochlorination is a major industrial method to produce vinyl chloride monomer (VCM). Traditionally, the manufacture of VCM relied on the use of a HgCl2/C catalyst, posing serious environmental concerns due to the loss of toxic Hg species from the surface of the support to the environment. Consequently, there has been an urgent need for the development of novel, environmentally friendly replacement catalysts. Chapter 3: In the first part of the thesis, a general approach to identify the best catalyst for the acetylene hydrochlorination reaction using a data set of key performance indicators has been introduced. The proposed universal method allows a direct comparison among metal and metal-free catalysts and demonstrates that Au-based catalysts are the best-in-class materials for this particular reaction. Chapter 4: This part of the study is focused on identifying the structure-activity relationship of the carbon support, and therefore a sequence of characterizations studies was performed. The physical and chemical properties of the carbonaceous materials, such as the texture, porosity, surface graphitization, surface functional groups, and surface acidic sites distribution were analysed. The results illustrated that the higher activity is associated with high porosity, high graphitization degree and low surface acidic groups. This work aims to illustrate a rationalized set of criteria for support evaluation and development. Chapter 5: In this study the effect that N-methyl-2-pyrrolidone (NMP) has on improving the activity and the stability of Au-based catalysts has been thoroughly investigated. Using a simple wet impregnation method, a 1 wt.% Au- NMP catalyst has been prepared. The study showed that the Au-NMP catalyst displays higher activity when tested at different temperatures in comparison to the standard catalyst, while it also exhibits a greater performance when compared to the commercial catalyst as validated at Johnson Matthey. Characterisation of the Au-NMP complex, including single crystal diffraction, Raman, IR spectroscopy and NMR, confirmed the coordination of the NMP to the Au centre via the N moiety, while it was identified that the structure of Au-NMP is a salt complex with a 1:2 ratio respectively. Finally, a series of NMP derivatives were used for the preparation of 1 wt.% Au-NMP(derivatives) illustrating that the co-existence of O and N is of a great importance for the high activity of the catalyst, as seen from the comparison of NMP with analogous structures.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	20 October 2023
Last Modified:	20 Oct 2024 01:30
URI:	https://orca.cardiff.ac.uk/id/eprint/163325

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