Hybrid Layered Double Hydroxides for CO2 Conversion to Useful Chemicals

Lead Research Organisation: University of Oxford

Abstract

Carbon dioxide (CO2) levels in the atmosphere have risen to over 400 ppm, as a result of human activities including the extraction and burning of fossil fuels for energy, and in the manufacture of a range of products in everyday life. In order to transition to net zero and keep temperature rises below the 1.5oC target of the Paris Agreement, two approaches are proposed - reduction in emissions through renewable sources of energy, and removal of CO2 from the atmosphere. Upon removal from the atmosphere, CO2 can be stored or used as a feedstock in chemical synthesis, for example for polymers or methanol.
The concept of the methanol economy was proposed by George A. Olah in the 1990s. Methanol is the simplest alcohol, composed of only one carbon atom, and can be used as a clean fuel, emitting only CO2 and water, and much smaller amounts of other toxic gases or soot compared to the combustion of fossil fuels. Methanol is currently produced from syngas, generated by reforming natural gas, over a metal catalyst at relatively high temperatures and pressures. However, alternative, more sustainable methods are currently being pursued. If methanol can be synthesised from captured CO2 and renewable hydrogen, this whole process becomes carbon neutral. In addition, methanol is a useful feedstock to the chemical industry to produce a range of more complex molecules, and is also used as a solvent. This is reflected in the global production of methanol, which reached 85 million tonnes in 2018, enough to fill an Olympic swimming pool every twelve minutes.
Layered double hydroxides (LDHs) are a class of ionic solid with a structure based on that of the naturally occurring mineral hydrotalcite. They are made of positively charged layers, which allows a range of negatively charged ions to be inserted in the interlayer space. The ability to vary the elements in the layered structure and the chemicals that can be inserted between means their properties can be tailored by researchers towards specific applications. These can range from adsorption to plastic additives to vehicles for drug delivery.
LDHs are also able to be used as catalysts, materials which speed up a chemical reaction, or enable it to occur in the first place. Recently, LDHs have been used to catalyse the addition of hydrogen gas to carbon dioxide, producing methanol, however with low overall yield. This project aims to synthesise more LDH materials incorporating different metals, which will be tested for the catalytic hydrogenation of carbon dioxide to produce methanol. Compared to previous work in this area, these will aim to have improved CO2 conversion and selectivity, and therefore increased overall methanol yield.

This project falls within the EPSRC manufacturing the future and physical sciences themes.

Planned Impact

The primary impact of the OxICFM CDT will be the highly-trained world-class scientists that it delivers. This impact will encompass both the short term (during their doctoral studies), the medium term (subsequent employment) and ultimately the longer timescale defined by their future careers and consequent impact on science, engineering and policy in the UK.

The impact of OxICFM students during their doctoral studies will be measured by the culture change in graduate training that the Centre brings about - in working at the interface between inorganic synthesis and manufacturing, and fostering cross-sector industry/academia working practices. By embedding not only from larger companies, but also SMEs, we have developed a training regime that has broader relevance across the sector, and the potential for building bridges by fostering new collaborations spanning enormous diversity in scientific focus and scale. Moreover, at a broader level, OxICFM offers to play a unique role as a major focus (and advocate) for manufacturing engagement with academic inorganic synthetic science in the UK.

From a scientific perspective, OxICFM will be uniquely able to offer a broad training programme incorporating innovative and challenging collaborative projects spanning all aspects of fundamental and applied inorganic synthesis, both molecular and materials based (40+ faculty). These will address key challenges in areas such as energy provision/storage, catalysis, and resource provision/renewal necessary to enhance the capability and durability of UK plc in the medium term. To give some idea of perspective, the output from previous CDTs in Oxford's MPLS Division include two start-up companies and in excess of 30 patents.

It is not only in the industrial and scientific realms that students will have impact during their timeframe of their doctorate. Part of the training programme will be in public engagement: team-based challenges in resource development/training and outreach exercises/implementation will form part of the annual summer school. These in turn will constitute a key part of the impact derived from the CDT by its engagement with the public - both face-to-face and through electronic/web-based media. As the centre matures, our aspiration is that our students - from diverse backgrounds - will act as ambassadors for the programme and promote even higher levels of inclusion from all parts of society.

For our partners, and businesses both large and small in the manufacturing sector, it will be our students who are considered the ultimate output of the OxICFM CDT. Our programme has been shaped by the need of such companies (frequently expressed in preliminary discussions) to recruit doctoral graduates who can apply themselves to a broad spectrum of multi-disciplinary challenges in manufacturing-related synthesis. OxICFM's cohort-based training programme integrates significant industry-led training components and has been designed to deliver a much broader skill set than standard PhD schemes. The current lack of CDT training at the interface of inorganic chemistry and manufacturing (and the relevance of inorganic molecules/materials to numerous industrial sectors) heightens the need for - and the potential impact of - the OxICFM CDT. Our students will represent a tangible and valuable asset to meet the long-term skills demand for scientists to develop new materials and nanotechnology identified in the UK Government's 2013 Foresight report.

In the longer term, the broad and relevant training delivered by OxICFM, and the uniquely wide perspective of the manufacturing sector it will deliver, will allow our graduates to obtain (and thrive in) positions of significant responsibility in industry and in research facilities/institutes. Ultimately we believe that many will go on to be future research leaders, driving innovation and changing research culture, and thereby making a lasting contribution to the UK economy.

Publications

10 25 50

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S023828/1 01/04/2019 30/09/2027
2714594 Studentship EP/S023828/1 01/10/2022 30/09/2026 Georgia Stonadge