Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Low-cost carbon capture gets X-rayed

01.08.2012
Diamond Light Source is being used to improve low cost methods for carbon capture.

Scientists from the University of Leeds are using the UK’s national synchrotron to investigate the efficiency of calcium oxide (CaO) based materials as carbon dioxide (CO2) sorbents. Their results, published in the journal of Energy & Environmental Science, provide an explanation for one of the key mechanisms involved. This new knowledge will inform efforts to improve the efficiency of this economically viable method of carbon capture and storage.

Current techniques for post-combustion carbon capture filter out CO2 from a power plant’s flue gases as they travel up a chimney. The filter is a solvent that absorbs the CO2, before being heated, releasing water vapour and leaving behind the CO2. In pre-combustion, the CO2 is filtered out by use of a catalytic converter before the fossil fuel is burned and the CO2 is diluted by other flue gases. These methods can prevent 80% to 90% of a power plant’s carbon emissions from entering the atmosphere.

CaO based materials have a large range of applications including pre- and post-combustion carbon capture technologies and thermochemical fuel upgrading. They are low cost, high abundance, have a large sorption capacity and fast reaction rates during the chemical process. They capture CO2 in the temperature range 400-800 °C via the formation of calcium carbonate (CaCO3) which can be regenerated with subsequent release of CO2, ready for compression and storage.
However, after multiple capture and regeneration cycles, the materials’ capacity for capture decreases due to the loss of surface area through sintering, a process that fuses powders together to create a single solid object. Although the surface area can be restored through hydration, the material suffers a reduction in mechanical strength. If these problems can be overcome, CaO based materials could provide a low cost answer for carbon capture on a very large scale.

Led by Dr Valerie Dupont and Dr Tim Comyn from the University of Leeds’ Faculty of Engineering, the team carried out a series of experiments on Diamond’s High resolution powder diffraction beamline, I11, using intense X-rays to study the carbon capture and hydration process in CaO based materials on the nano-scale. Their observations suggest a mechanism for the interaction between CaO and water during hydration.

“We found that the stresses in the calcium hydroxide phase when bound to CaO were more than 20 times higher than its strength, leading to disintegration and the generation of nano-sized crystallites. Although the generation of a high surface area is a good thing, mechanical friability needs to be kept in check in order to achieve long term reliability for these systems. Our analysis provides an explanation of the enhanced capture/disintegration observed in CaO in the presence of steam. Now we understand this, the next step is to develop methods for improving the materials used, and apply the same techniques to other systems.”

Dr Tim Comyn, Faculty of Engineering, University of Leeds

CaO readily forms a shell of calcium hydroxide when exposed to water in the air (right). Due to differences in atomic congurations (top left) between the oxide and hydroxides, enormous strains develop due to the interface. These strains of 0.78% lead to stresses 20 times higher than the rupture strength of the hydroxide leading to rupture and the generation of nanoparticles.

Deconvolution of the data generated by Diamond (bottom left) allows the Leeds team to determine the size and strain in these layers, from the breadth of the peaks (the peaks from CaOH are far narrower than CaO). Conventional X-ray sources would have considerable peak overlap, making this type of analysis almost impossible.

Roger Molinder, an Engineering and Physical Sciences Research Council (EPSRC) funded PhD student on the project, describes, “Using the high resolution powder diffraction beamline at the Diamond synchrotron was key to this discovery; conventional X-ray sources such as those found at most Universities in the UK provide data with broad peaks, which do not make this sort of analysis possible. From a rigorous analysis of peak shapes arising from the data, we were able to determine the shape and size of the hydroxide phase, and determine the level of stress. Knowledge of these derived parameters is key to understanding the mechanism of sintering/disintegration.”

Concerns about global warming have prompted both national and international efforts to curb CO2 emissions. CaO based materials are a promising candidate for the removal of CO2 from flue gases at temperatures between 400 and 800 °C from processes such as fossil-fuel combustion. They are also being considered as a means to remove the CO2 that is generated as a result of thermochemical fuel upgrading with biomass sources, which are growing more and more popular as an alternative to fossil fuels. Using CaO based materials for carbon capture is just one of the ways to combat global warming. Since CaO based materials are low cost, there is an economic incentive to solve the problem of surface area loss to potentially turn this into a method for large scale CO2 capture. These recently published results are a promising step towards improving these low cost methods.

The accepted manuscript for ‘In-situ X-ray diffraction of CaO based CO2 sorbents’ was published online 9 July 2012 in Energy & Environmental Science. DOI:10.1039/C2EE21779A

Paula Gould | EurekAlert!
Further information:
http://www.leeds.ac.uk

More articles from Physics and Astronomy:

nachricht Pulses of electrons manipulate nanomagnets and store information
21.07.2017 | American Institute of Physics

nachricht Vortex photons from electrons in circular motion
21.07.2017 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>