Researchers in the UK have created a new low-cost material that could help tackle global warming by capturing and storing harmful greenhouse gases from power stations.
The porous material, named NOTT-300, has the potential to reduce fossil fuel emissions by trapping polluting gases such as carbon dioxide (CO2) and sulphur dioxide (SO2). The system would be cheaper and more efficient than current methods of capturing gases, which are expensive and use large amounts of energy.
Scientists at the University of Nottingham worked on the project to develop the innovative new material together with researchers from the University of Oxford and Peking University in China. The team say NOTT-300 captured close to 100 per cent of the carbon dioxide in experiments using a cocktail of gases, representing a major step towards creating a low carbon economy – producing energy using low-carbon sources and methods.
The new material, made from aluminium nitrate salt, cheap organic materials and water as the only solvent, is non-toxic and requires less energy to strip out the carbon when it becomes saturated.
In addition to high capacity and selectivity – the ability to soak up the polluting gases – it is also very easy to release the adsorbed gas molecules in NOTT-300 through the simple reduction of pressure. The material has high chemical stability to all common organic solvents and is stable in water and up to temperatures of 400°C.
The scientists say the material has many potential applications, with one of the most important being the reduction of CO2 and SO2 from flue gases in large industrial emitters, such as fossil fuelled power stations.
NOTT-300 could also act as a filter to purify natural gas, which needs any CO2 impurities removed before it can be used. The CO2 is readily captured by the material while the methane in the gas will just pass through without being adsorbed.
Professor Martin Schröder, Dean of the Faculty of Science at The University of Nottingham, led the research. He said: “Our novel material has potential for applications in carbon capture technologies to reduce CO2 emissions and therefore contribute to the reduction of greenhouse gases in the atmosphere.
“It offers the opportunity for the development of an ‘easy on/easy off’ capture system that carries fewer economic and environmental penalties than existing technologies. It could also find application in gas separation processes where the removal of carbon dioxide or acidic gases such as sulphur dioxide is required.”
Prof Schröder added: “It is widely accepted that it is imperative that the CO2 footprint of human activity is reduced in order to limit the negative effects of global climate change. There are powerful drivers to develop efficient strategies to remove CO2 using alternative materials that simultaneously have high adsorption capacity, high selectivity for CO2 and high rates of regeneration at an economically viable cost.
“The material shows high uptake of CO2 and SO2. In the case of SO2, this is the highest reported for the class of materials to date. It is also selective for these gases, with other gases – such as hydrogen, methane, nitrogen, oxygen – showing no or very little adsorption into the pores.”
The research, published in the scientific journal Nature Chemistry, demonstrates how the exciting properties of NOTT-300 could provide a greener alternative to existing solutions to adsorb CO2 which are expensive and use large amounts of energy
Scientists described the capture mechanism as “similar to Velcro” in that the material selectively captures the gases from the flue gas and holds them until they can be “peeled off” at low pressure and stored.
Carbon capture has not yet been proven on a commercial scale and pilot projects have been hindered by concerns that the ammonia-based materials, or amines, used to absorb carbon can themselves produce toxic emissions. They are also expensive and need large amounts of heat to boil out the carbon so it can be taken away and stored. The researchers say NOTT-300, could overcome all these problems.
Dr Timmy Ramirez-Cuesta, who worked on the project at the ISIS research centre at the Rutherford Appleton Laboratory in Oxfordshire, said the new material could simplify carbon capture by using interchangeable filters.
“One could envisage a system that consists of two large containers that contain this material,” he said. “If you flow the exhaust gases from a power station through the first container, the material will selectively capture the carbon dioxide.
“When the material is saturated, the exhaust gases are diverted to the second container where the process continues. The full container is disconnected from the system and the CO2 is removed using a vacuum and collected. The regenerated container can then be reconnected and used repeatedly.”
The scientists said they are working with companies in the carbon capture business to make the new material a commercial reality. Although the rate could be lower in the "dynamic conditions" of a real power station, it should still be over 90 per cent, which is a key test for the viability of an absorber.