Methane in shale gas can be converted into hydrocarbon fuels with the help of an innovative platinum and copper alloy catalyst, according to new research headed by University College London (UCL) and Tufts University.
Platinum or nickel are known for breaking the carbon-hydrogen bonds in methane present in shale gas in order to make hydrocarbon fuels and various other useful chemicals. However, this process leads to 'coking' - the metal ends up becoming coated with a carbon layer causing reactions to be blocked from taking place at the surface.
The new alloy catalyst is known to be resistant to coking, thus retaining its activity and requiring less energy to break the bonds than other materials.
Presently, methane reforming processes are very energy intense, needing temperatures of about 900 oC. This new material is capable of lowering this to 400 oC, thus saving energy.
The study, published on Jan 8th, 2018, in Nature Chemistry, shows the benefits of the new highly diluted alloy of platinum in copper - a single atom alloy - in producing useful chemicals from tiny hydrocarbons.
A mixture of powerful computing techniques and surface science and catalysis experiments were used for examining the performance of the alloy. These demonstrated that the platinum breaks the carbon-hydrogen bonds, and the copper enables coupling hydrocarbon molecules of varied sizes, further enabling the conversion to 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.
Michail Stamatakis, Co-Lead Author
While UCL researchers were able to trace the reaction using computers, Tufts chemical engineers and chemists ran surface science and micro-reactor experiments in order to demonstrate the feasibility of the new catalyst - atoms of platinum dispersed in a copper surface - in a practical situation. They discovered that the single atom alloy was extremely stable and needed only a small amount of platinum to work.
Study head, Professor Charles Sykes of the Department of Chemistry in Tufts University's School of Arts & Sciences, said: "Seeing is believing, and our scanning tunneling microscope allowed us to visualize how single platinum atoms were arranged in copper. Given that platinum is over $1,000 an ounce, versus copper at 15 cents, a significant cost saving can be made."
Together, the team demonstrates that less energy is required for the alloy to enable breaking the bonds between hydrogen and carbon atoms in butane and methane, and that the alloy is resilient to coking, thus making room for new applications for the material.
Study co-lead author, Distinguished Professor Maria Flytzani-Stephanopoulos of the Department of Chemical and Biological Engineering in Tufts University's School of Engineering, said: "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."
The team currently plans on developing further catalysts that are considered to be similarly resistant to the coking that was traditionally used by plagues metals in this and various other chemical processes.
The research involved scientists from UCL and Tufts and employed computing resources from UCL and the Argonne National Laboratory. The US Department of Energy, The Engineering and Physical Sciences Research Council, European Research Council and the Royal Society funded the research.