A scanning tunneling microscope image of reaction intermediates on copper (111) and platinum/copper single atom alloy surfaces. Image: Sykes.Methane in shale gas can be turned into hydrocarbon fuels using an innovative platinum and copper alloy catalyst, according to new research led by scientists at University College London (UCL) in the UK and Tufts University.
Platinum or nickel can break the carbon-hydrogen bonds in the methane found in shale gas to make hydrocarbon fuels and other useful chemicals. But this process causes 'coking' – the metal becomes coated with a carbon layer rendering it ineffective by blocking further reactions from happening at the surface.
The new alloy catalyst is resistant to coking, and so retains its activity and requires less energy to break the bonds than other catalysts. Currently, methane reforming processes are extremely energy intense, requiring temperatures of about 900°C. The new catalyst could lower this to 400°C, saving energy.
The study, reported in a paper in Nature Chemistry, demonstrates the benefits of the new highly diluted alloy of platinum in copper – a single atom alloy – in making useful chemicals from small hydrocarbons.
The scientists used a combination of surface science and catalysis experiments with powerful computing techniques to investigate the performance of the alloy. These showed that the platinum breaks the carbon-hydrogen bonds, while the copper helps couple together hydrocarbon molecules of different sizes, paving the way towards conversion into fuels.
"We used supercomputers to model how the reaction happens – the breaking and making of bonds in small molecules on the catalytic alloy surface, and also to predict its performance at large scales. For this, we needed access to hundreds of processors to simulate thousands of reaction events," said co-lead author Michail Stamatakis, a professor in chemical engineering at UCL.
While UCL researchers traced the reaction using computers, Tufts chemists and chemical engineers ran surface science and micro-reactor experiments to demonstrate the viability of the new catalyst – atoms of platinum dispersed in a copper surface – in a practical setting. They found the single atom alloy was very stable and only required a tiny amount of platinum to work.
"Seeing is believing, and our scanning tunneling microscope allowed us to visualize how single platinum atoms were arranged in copper," said lead author Charles Sykes, a professor in the Department of Chemistry at Tufts University. "Given that platinum is over $1000 an ounce, versus copper at 15 cents, a significant cost saving can be made."
Together, the team showed that less energy is needed for the alloy to help break the bonds between carbon and hydrogen atoms in methane and butane, and that the alloy is resistant to coking, opening up new applications for the material.
"While model catalysts in surface science experiments are essential to follow the structure and reactivity at the atomic scale, it is exciting to extend this knowledge to realistic nanoparticle catalysts of similar compositions and test them under practical conditions, aimed at developing the catalyst for the next step – industrial application," said co-lead author Maria Flytzani-Stephanopoulos, a professor in the Department of Chemical and Biological Engineering at Tufts University.
The team now plan to develop further catalysts that are similarly resistant to the coking that plagues metals traditionally used in this and other chemical processes.
This story is adapted from material from UCL, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.