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Diamond Celebrates its 6000th Paper

Date: 
Monday, November 20, 2017
Contact: 

For further information or photographs;

Isabelle Boscaro-Clarke Head of Communications Diamond House Diamond Light Source Harwell Campus Didcot OX11 0DE T: 01235 778130 E: Isabelle.boscaro-clarke@diamond.ac.uk

To find out more about the B18 beamline, or to discuss potential applications, please contact Principal Beamline Scientist Dr Giannantonio Cibin: giannantonio.cibin@diamond.ac.uk

Plasma-aided catalysis – an important step towards reducing greenhouse gas emissions

Diamond Light Source, the UK’s national synchrotron today (20th November 2017) revealed that it has reached and exceeded a very significant milestone with the publication of the 6000th scientific paper by one of its research users in Angewandte Chemie.

Set-up on the B18 beamline.

The 6000th paper was authored by a consortium of researchers in a collaboration between industry - Johnson Matthey - and academia. A key goal for the research consortium is to find ways of curbing the release of methane into the atmosphere. Methane is a major contributor to climate change, with a global warming potential around 21 times higher than that of CO2. Methane is released from landfill sites and leaks from natural gas storage and distribution, but is also emitted in vehicle exhausts. Non-thermal plasmas (NTPs) can be used to assist catalytic reactions that otherwise only take place at high temperatures, but the way in which they work is not well understood. The consortium’s study investigates the role of NTPs in the catalytic oxidation of methane into CO2 and water.

“Our 6000th paper demonstrates the huge impact that synchrotron research is having and how it is helping us tackle many of the major challenges that affect us all. Diamond is working with these researchers to help them find a route to minimise the impact of methane, by examining catalysts in situ, to find how it can be transformed into less harmful CO2.

This is another example of the amazing research taking place here at Diamond, which shows how we are changing the face and pace of scientific advances for our UK and international science communities. This is our 10th year in operation and the number of papers being published is accelerating. Typically we anticipate over 1000 papers annually, a growth in line with our operations. Knowledge at this generation scale is essential and leads to innovtaions that sometimes we cannot anticipate” Andrew Harrison, CEO at Diamond

Dr Emma Gibson, who was at the UK Catalysis Hub, Research Complex at Harwell, during the time of the study, explains that to date there are few studies of these hybrid NTP catalyst reactions in situ, and none that specifically measure the catalyst. To do the research, the team turned to the B18 beamline at Diamond.

A general-purpose X-ray absorption spectroscopy (XAS) beamline, B18 allowed the team to use X-ray absorption fine structure (XAFS) to probe the oxidation state and structure of palladium catalyst nanoparticles during methane oxidation. They also used mass spectrometry to track the reaction products, confirming oxidation of methane to CO2 and water was taking place.

The results showed that during the reaction, there are no significant structural changes to the catalyst. The palladium nanoparticles are heated, but not to a level that would activate the thermal oxidation of methane. This suggests that the presence of the NTP allows a different reaction pathway to occur.

Dr Gibson explains: “The plasma somehow heats the catalyst up but not to the same temperature you would need to do the classic thermal reaction. The NTP heats the palladium nanoparticles to 162°C, far below the 300°C normally required, suggesting that the NTP is affecting the reaction in another

way. We believe the plasma could be assisting the removal of the first hydrogen from the methane – the rate determining step in the oxidation – therefore lowering the reaction’s activation barrier. While we haven’t discovered the full story yet, we have been able to open up a new way of probing these reactions by turning our attention to the catalyst.”

The team now hope to use the beamline technique to study other reactions such as the selective catalytic reduction of NOX.

Assisting catalytic oxidations

Researchers used the Core X-ray Absorption Spectroscopy (XAS) beamline (B18) at Diamond to study the NTP catalytic oxidation of methane by Pd/Al2O3. It is the first investigation to study the catalyst in this type of reaction in situ. X-ray absorption fine structure (XAFS) measurements taken from the beamline show the NTP plays a role in increasing the temperature of the palladium catalyst, but not

to the extent needed to carry out the corresponding thermal reaction without the NTP present. They surmise that the NTP must also lower the activation energy, by offering an alternative pathway for the reaction to proceed.

Palladium is an efficient catalyst for methane oxidation, and has been extensively studied. However, current palladium catalysts are inefficient under cold conditions, due to the high activation barriers to methane dehydrogenation. NTPs provide a way to circumnavigate this problem as they can allow these reactions to take place at room temperature. NTPs are partially ionised gases in which energy is stored mostly in free electrons and the overall temperature remains low. However, despite the efficacy of NTPs, their mode of operation remains unknown. Researchers have put forward three probable ways they could assist the reaction – the plasma might modify the catalyst, it might heat the catalyst, or it might permit new reaction pathways.

The Team: Dr. Emma K Gibson, Dr. Cristina E Stere, Bronagh Curran-McAteer, Wilm Jones, Dr. Giannantonio Cibin, Dr. Diego Gianolio, Prof. Alexandre Goguet, Dr. Peter P. Wells, Prof. C. Richard A. Catlow, Dr. Paul Collier, Dr. Peter Hinde, Prof. Christopher Hardacre

Related publication: (in following format)

Gibson EK et al. Probing the Role of a Non-Thermal Plasma (NTP) in the Hybrid NTP Catalytic Oxidation of Methane. Angew Chem Int Ed 56, 9351 (2017).

DOI: 10.1002/anie.201703550

 

About Diamond Light Source http://www.diamond.ac.uk/

Diamond Light Source is the UK’s national synchrotron. It works like a giant microscope, harnessing the power of electrons to produce bright light that scientists can use to study anything from fossils to jet engines and viruses to vaccines.

The machine accelerates electrons to near the speed of light so that they emit light 10 billion times brighter than the Sun. These bright beams are then directed off into laboratories known as ‘beamlines’. Here, scientists use the light to study a vast range of subject matter, from new medicines and treatments for disease to innovative engineering and cutting-edge technology.

Whether it’s fragments of ancient paintings or unknown virus structures, at the synchrotron, scientists can study their samples using a machine that is 10,000 times more powerful than a traditional microscope.

Diamond is one of the most advanced scientific facilities in the world, and its pioneering capabilities are helping to keep the UK at the forefront of scientific research.

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