PhD in Chemistry: Modelling Approaches to p-Xylene Oxidation Catalysis

This is a collaborative project with industry that seeks to use computational modelling methods to gain deeper insights into what is globally one of the most important petrochemical processes.

Terephthalic acid is used in the production of polyethylene terephthalate (PET) and global annual production is ~80 Mt. Terephthalic acid is synthesised by the oxidation of p-Xylene in the presence of O2, through a catalyst-initiated free radical chain mechanism using a [CoII/IIIMnII/IIIBrx(HOAc)y] complex. Many mechanistic aspects of the transformation of p-Xylene to terephthalic acid are poorly understood for such a large-scale industrial process; scholarly study and characterisation of important catalyst species is extremely challenging due to the harsh operating conditions and paramagnetic nature of intermediates.

Modern computational modelling techniques now present an exciting opportunity to critique current knowledge, develop further understanding and improve key aspects of this catalytic process. Using ab initio computational techniques to accurately sample reaction conditions, this project will validate the empirically derived understanding of the catalyst and investigate the properties of the catalytic active species, providing new opportunities for upgrading of the industrial protocol.

Aims and Method:

Our overall aim is to complete the first computational modelling study of the reaction conditions for oxidation of p-Xylene, and through this to better define the catalytically relevant species and mechanism of the process. Specific objectives are:
- To identify the structure and redox coupling of the Co-Mn-Br catalyst under operating conditions
- To define the chemical interactions between reagents (p-Xylene, p-toluic acid) and catalyst
- To elucidate how changes in solvent conditions and catalyst composition affect productivity

These aims will be pursued using a range of computational simulations for catalysts, reactants and solvents, in order to evaluate redox coupling and reaction barriers; to accurately reproduce experimental conditions, it will be also necessary to perform extensive dynamical simulations with a combination of canonical (NVT) and isothermal-isobaric (NPT) configurations. Molecular dynamics offers insight into the coordination of reactants, solvents and catalysts at operating conditions, as well as providing a facile approach for investigating previously unsampled chemical space (e.g. alternative reaction pathways). The simulation results will be coupled with the experimental work of our collaborators to provide unparalleled insight.


Research Environment:

You will join the established research teams of Dr Logsdail and Prof. Wass, with a combination of ca. 10 PDRA/PhDs across the research groups. The groups have a wealth of expertise in computational simulation and homogeneous catalysis, respectively, and are integrated within the Cardiff Catalysis Institute (CCI), which is an internationally acclaimed centre for catalytic chemistry; through the CCI, you will have access to leading expertise in catalytic and computational chemistry. Cardiff University is also a key stakeholder in the national high-performance computing facility, Supercomputing Wales, through which you will have access to state-of-the-art computing infrastructure and training opportunities.

You will also be supported by INVISTA Performance Technologies (Dr Keith Whiston) https://ipt.invista.com/ who are a leading licensor of technology in the polyester value chain globally. INVISTA will provide regular ongoing opportunities for engagement with industry and opportunities to impact real world manufacturing technology through the project.

Training and Development:

You will be trained in a range of computational simulation approaches, including geometry optimisation, solvation and molecular dynamics, all performed at the density functional theory (DFT) level of theory. You will receive expert support and training directly from the supervisory team (Dr Logsdail). More broadly, you will have access to the enhanced training programme within the Cardiff Catalysis Institute, which encompasses training on homogeneous, heterogeneous and biological catalysis. You will also develop transferable skills through your interaction with project partners, preparation of reports and presentations at meetings and conferences. The supervisory team’s combination of expertise in computational modelling, homogeneous and industrial catalysis will facilitate your rapid progress and provide a wealth of training opportunities.

Applicants should apply to the Doctor of Philosophy in Chemistry with a start date of October 2020.
In the research proposal section of your application, please specify the project title and supervisors of this project and copy the project description in the text box provided. In the funding section, please select ’I will be applying for a scholarship/grant’ and specify that you are applying for advertised funding from PhD in Chemistry: Modelling Approaches to p-Xylene Oxidation Catalysis.

You must hold (or expect to hold) a chemistry degree at the 2:1 level or higher. Experience in computational chemistry and catalysis would be a significant advantage but are not a pre-requisite since full training will be provided.