Research interests and output
Catalysis plays an essential role in physiology, nature, and the production of chemicals and fuels. Research in the Hammond group is situated at the interface of chemistry and chemical engineering, and focuses on the design and application of new heterogeneous catalysts for the production of energy and chemicals. Typically, a combination of crosscutting techniques is utilised in order to prepare novel (improved) and highly selective materials for new (established) catalytic processes. In depth kinetic and mechanistic analyses of the synthesised catalysts are combined with in situ spectroscopic analysis and theoretical models of the catalytic active sites pre-, post- and during-operation with the aim of developing (1) molecular-level structure-activity-lifetime relationships, and subsequently (2) tailor-made heterogeneous catalysts that are more active, selective and stable on a macroscopic scale. Our group has several major themes of interest, some of which are described below.
- Design and utilisation of novel heterogeneous catalysts
A major focal point of our research is the synthesis and development of highly active, heterogeneous catalysts, such as metal (oxide) nanoparticles, and porous materials such as zeolites, zeotypes, HPAs, POMs, MOFs, and ZIFs. These materials offer an exciting opportunity to tune and tailor a number of catalytic functionalities, such as redox activity, acid-base properties, Lewis and/or Brønsted acid ratio, and pore architecture, each of which can have a profound impact on the catalytic process of interest. Principally, we are interested in:
- The application of these materials as liquid phase acid and/or oxidation catalysts (see 2), particularly in continuous reactors (see 3);
- Understanding the influence of zeotype composition and framework architecture on the speciation and reactivity of various heteroatoms;
- The utilisation of metal oxide nanoparticles for anti-cancer nanotherapeutics and imaging challenges.
- Advanced catalytic processes
The materials we study and design are employed as heterogeneous catalysts for a wide range of processes. However, several particular systems are of high priority for our group, including the following:
- The activation and functionalisation of inert C-H bonds remains one of the most elusive targets in catalysis, particularly with the discovery of new natural/shale gas reserves. Our research in this area focuses on the functionalisation of lower-to-mid alkanes with heterogeneous catalysts through oxidative and non-oxidative methods.
- The selective oxidation of organic molecules is one of the most fundamentally important chemical processes across all levels of the value chain. Research in our group focuses on the development and optimisation of sustainable oxidation processes with more favourable oxygen donors, such as dioxygen and H2O2. Key examples include the epoxidation/dihydroxylation of olefins, Baeyer-Villiger oxidations, and the oxidation/ODH of alkanes, alcohols and amines.
- The dwindling supply of fossil resources, coupled with increasing awareness of their polluting nature and environmental impact, necessitates an optimisation of existing technologies, and the development of alternative and more sustainable routes to the major building blocks of the chemical industry. Our research in this area focuses on the valorisation of alternative feedstock (methane/shale gas, bio-renewable substrates, CO2) primarily for the production of chemicals.
- Intensification of catalytic chemistry
In addition to high levels of catalytic activity and target product selectivity, promising heterogeneous catalysts must also possess sufficient levels stability i.e. lifetime, and be amenable for scale up, in order for industrialisation to be realised. A major focus point of our research, therefore, is the intensification of catalytic chemistry. Critical elements of this research include:
- Designing deactivation-free catalytic systems: A major challenge in our research is to design catalytic systems that are amenable for continuous operation. We achieve this by performing in-depth studies of catalysts under continuous conditions (with kinetic and in situ spectroscopic methods), in order to identify (1) how and why particular catalysts deactivate, and subsequently (2) optimise the operational conditions, and design novel materials, that are resistant to these events. Key elements of this research are reactor engineering and in situ spectroscopy, especially with techniques such as resonance Raman and UV-Vis.
- Scalable catalyst preparation methodologies: A critical challenge in contemporary catalytic science is the development of new preparation methodologies that are suitable for industrial scale employment. In this regard, we develop novel methods of catalyst preparation, such as mechanochemical (solid state) synthesis, to design scalable catalytic materials.
- Water purification
Water is the world’s most precious resource. As stated by the World Heath Organisation, “all people, whatever their stage of development and their social and economic conditions, have the right to have access to an adequate supply of safe drinking water.” Yet, a significant, and increasing, fraction of the world’s population, especially in the developing world, does not enjoy this right. Our research in this area targets the decontamination of ground water via catalytic and separation methods.
- Bio-mimetic catalysis
Naturally occurring metalloenzymes typically possess a transition metal centre, and are able to perform extremely challenging catalytic reactions (e.g. oxidations) at ease, under mild reaction conditions, and with exquisite chemo- and stereo-selectivity. Understanding the chemistry of these metalloenzymes, and subsequently tailoring inorganic materials that are able to mimic them is a key challenge of fundamental and practical relevance. In addition, our group focuses on the immobilisation and/or encapsulation of naturally occurring metalloenzymes, to produce hybrid biological-inorganic heterogeneous catalysts for catalytic processes.