UCL, Tufts find new catalyst to turn shale gas into fuel

A NEW platinum and copper alloy catalyst developed at University College London, UK, and Tufts University, US, can convert shale gas methane into liquid fuels more efficiently than conventional catalysts.

As shale gas production booms, producers are increasingly looking for ways to increase its value. One way is to turn the methane gas in shale into liquid hydrocarbon fuels. Platinum and nickel catalysts can break the carbon-hydrogen bonds to achieve this, but are prone to becoming coated with a carbon layer, known as ‘coking’, which deactivates them. In addition, current methane reforming processes require temperatures in excess of 900^oC.

The new catalyst developed by UCL and Tufts is what is known as a “single atom alloy”, with platinum atoms dispersed on copper. Not only is it resistant to coking in methane reforming, but can lower the reaction temperature to 400^oC, which would result in significant energy savings.

The researchers used surface science and catalysis experiments to investigate the catalyst’s performance and to determine how it works. At UCL, the team used computers to trace the reaction.

“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 UCL chemical engineer professor Michail Stamatakis.

They found that the platinum breaks the carbon-hydrogen bonds, while the copper couples the hydrocarbon molecules back together.

The Tufts team meanwhile used surface science and micro-reactor experiments to determine the catalyst’s practical viability. Scanning tunnelling microscope imaging showed exactly how the platinum atoms are arranged.

“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 Tufts distinguished professor of chemical and biological engineering Maria Flytzani-Stephanopoulos.

The researchers now hope to develop more catalysts that are similarly resistant to coking.

Nature Chemistry doi.org/ch46