Benchtop NMR spectroscopy can accurately analyse pyrolysis oils
A team of researchers at Aston University has demonstrated that benchtop spectrometers are capable of analysing pyrolysis bio-oils just as well as far more expensive, high-field spectrometers.
Bio-oils resulting from the intense heating (pyrolysis) of industrial or agricultural by-products, are increasingly seen as potential alternatives to fossil fuels. But the stability and consequent treatment of these bio-oils depends entirely on their composition; and since they are often mixtures of many dozens, or hundreds, of different compounds, analysing such complex mixtures is not simple – or cheap.
Dr Robert Evans, Senior Lecturer in Physical Chemistry at Aston University, explains: “The composition of any pyrolysis bio-oil is absolutely key to future use. For example if there are oxygen-containing chemicals in the oil, that will make the oil more corrosive and it will be more unstable. So in particular we need to know if carbonyl groups are present – where oxygen and carbon atoms are bonded together – as these can have a major impact.”
A leading method of analysis is high-field nuclear magnetic resonance (NMR) spectroscopy, which gives a detailed breakdown of the identity and concentration of chemical species present in any sample. However these large high-field NMR spectrometry machines cost in the range of £600,000-£10million and require a supply of expensive cryogens and solvents, so are generally only found in the very biggest research facilities.
The team at Aston, led by Dr Evans, set out to see if ‘low-field’, or benchtop, NMR spectrometers, could analyse pyrolysis oils well enough to produce the necessary detailed information. Benchtop NMR spectrometers use permanent magnets, which don’t require cryogenic cooling, so cost much less to purchase and maintain. However, using lower strength magnets comes at the cost of lower sensitivity and poorer resolution. While they can find some use as research instruments, they are also commonly found in teaching laboratories.
The study, carried out with collaborators at the University of Tennessee, tested pyrolysis oils produced from a number of different plants, and compared the results from benchtop spectrometers to both high-field spectrometers and other methods of analysis. They found that the benchtop machine estimates compared favourably with titration analysis for overall carbonyl content, as well as matching high-field spectrometry for the specific identification of carbonyl groups such as ketones, aldehydes and quinones.
Dr Evans said: “Despite the known limitations of benchtop spectrometers, a very similar quality of NMR data could be obtained for these samples, enough to accurately estimate concentrations of different classes of carbonyl-containing species. Using benchtop spectrometers will make NMR analysis of pyrolysis oils much simpler, cheaper, and more accessible to a wider range of different users.”
Quantitative Low-Field 19F NMR Analysis of Carbonyl Groups in Pyrolysis Oils is published online today in ChemSusChem, a journal of Chemistry Europe.
Cautious welcome to UK’s new Biomass Strategy
A group of bioenergy experts have welcomed the Government’s new UK Biomass Strategy, but say urgent action is now vital to shape its ambitions into deliverable policies.
Researchers at the Supergen Bioenergy Hub – led by Aston University – worked closely with government departments to provide scientific evidence to inform the strategy, which outlines the role biomass will play in supporting the UK’s transition to net zero and how this will be achieved.
Professor Patricia Thornley, who leads the Hub, says: “This is a comprehensive and considered biomass strategy that, rightly, places sustainability at the heart of UK bioenergy development. The challenge is now to produce actions that can deliver the sustainable system of biomass required to achieve net zero.”
Sustainability is a major theme within the new strategy. It includes a review of how existing sustainability policies could be improved, as well as a commitment to developing a cross-sectoral sustainability framework (subject to consultation) to ensure sustainability across the many different applications of biomass. This follows previous work led by Dr Mirjam Rӧder, Systems Topic Group Lead in the Supergen Bioenergy Hub, calling for harmonised sustainability standards across different biomass applications, which is referenced in the strategy.
Dr Rӧder says: “We need rigorous approaches to sustainability governance that go beyond emissions. Considering wider environmental, social and economic trade-offs is essential for true sustainability and building trust in bioenergy projects.”
The strategy considers the amount of biomass resource that might be available to the UK in the future, highlighting the importance of both imported and domestically produced biomass resources. Professor Thornley comments: “It is important that the strategy recognises the potential of imported as well as indigenous biomass in achieving global greenhouse gas reductions. Sustainable systems should grow, convert and use biomass in the locations where they can deliver most impact, ensuring we take account of all supply chain emissions. We shouldn’t shy away from imports where the source is sustainable and the overall system makes environmental, economic and social sense.”
The strategy also considers how biomass should be prioritised across a variety of applications to best support the transition to net zero. Biomass applications ranging from transport fuels and hydrogen to domestic and industrial heating are recognised as important, but in the medium to long term the focus is on integration of bioenergy with carbon capture and storage (BECCS).
BECCS is an emerging technology where the CO2 that may be released during the production and use of electricity, fuels or products derived from biomass is captured and stored, potentially resulting in negative emissions.
Professor Thornley comments: “The priority use framework outlined in the Biomass Strategy makes eminent sense. The UK (and the global energy system) needs carbon dioxide removals to deliver net zero. BECCS has an absolutely key role to play, as reflected in the strategy. Again, while this is encouraging to see, we must not underestimate the challenges of moving towards such a radically different system at scale.”
“Relying on future BECCS deployment alone to counterbalance the current excess of greenhouse gas emissions would not enable the full potential and benefits of BECCS. BECCS should be deployed alongside measures to transition away from the use of fossil fuels, not instead of them,” adds Dr Joanna Sparks, Biomass Policy Fellow at the Supergen Bioenergy Hub, who engaged closely with government departments as they developed the strategy.
Dr Sparks led an extensive policy engagement and knowledge transfer process to ensure that those developing the strategy had full access to the breadth and depth of UK scientific and engineering academic expertise, ensuring a robust, independent scientific base.
Professor Thornley believes continued engagement between policymakers, academics and the wider sector is vital in achieving the next steps in the delivery of the Government’s strategy. She says: “The key to successful long-term results is a close partnership between academia, industry and policy stakeholders so that we can anticipate problems and plan the pathways to success.”
New glass sensors could make commercial nuclear fusion viable
A new generation of durable sensors capable of monitoring commercial nuclear fusion reactors in real time is being developed by UK researchers.
The team, led by Bangor University in partnership with Sheffield Hallam University, plan to identify whether glass sensors developed in 1960s could function in the extreme conditions of a nuclear fusion reaction. If not, the researchers will design and develop new glass sensors.
In December 2022, researchers in the United States for the first time generated more energy from a nuclear fusion reaction than was put in, opening up the possibility that the technology could be both commercially viable, and able to supply abundant, clean energy. But one of the requirements to move from experimental reactions to commercial power generation is reliable monitoring. This means overcoming the extreme conditions created in a fusion reaction: temperatures of 150-200 million degrees Centigrade and highly energetic fast-moving neutrons.
One way of monitoring a fusion reaction is to count the number of neutrons it gives off using scintillators – blocks of material in which a sparkle of light is created each time it is hit by a neutron. By counting the flashes of light, it’s possible to calculate the number of neutrons and the amount of energy being produced – helping to ensure everything is working as intended.
However, existing scintillators are mostly made from either crystal or polymer, which are either difficult to make and limited in size and shape, or lack the durability to withstand the more extreme conditions created by fusion reactions. The sensors currently used to calculate the energy output from fusion reactions tend to be cumbersome and awkward, and do not allow real-time and long term monitoring of the fusion process. For commercial nuclear fusion reactors to be run safely and efficiently, sensors will need to work reliably for years.
Dr Michael Rushton from Bangor University’s Nuclear Futures Institute is leading the new project. He said: “Glass has intrinsic radiation tolerance, so can survive well in very harsh conditions. It also has the advantage that it can be made in very different shapes, from fibres to plates which means sensors can be made for a range of situations within a reactor. And it’s fairly low cost to manufacture. We also hope to be able to ‘tune’ the sensors to work with different types of radioactive particle, so they may also be used for other applications, such as airport or medical scanners.”
Glass sensors able to register radioactive particles were first developed in the 1960s, but they only work if particles are travelling relatively slowly. The Bangor University team is initially seeing if particles emanating from a fusion reaction could be slowed down sufficiently to allow these sensors to work based on their existing composition. If this isn’t possible, then they will use machine learning approaches to identify new configurations of glass that could be effective in the conditions found within nuclear fusion. The new sensor designs will then by manufactured by their colleagues at Sheffield Hallam University.
Professor Paul Bingham from Sheffield Hallam University said: “This research will develop an entirely new range of glass-based sensors for some of the most extreme environments on Earth. This means it could not only help accelerate safe development and deployment of fusion energy technologies, but also have wide-ranging applications in other fields in the future.”
The two-year research project is funded through UK Research and Innovation’s Engineering and Physical Sciences Research Council. It involves Bangor and Sheffield Hallam Universities, the University of Birmingham, the ISIS Neutron and Muon Source at the Science and Technology Facilities Council (STFC) Rutherford Appleton Laboratory as well as a number of commercial partners.