On the way to green chemistry

The chemical industry needs huge amounts of hydrogen and ethanol to produce fertilisers or plastics, for example. Up to now, these basic materials have primarily been made from natural gas. New processes are needed in order to switch to green chemistry with no CO₂ emissions. Catalysts – which accelerate chemical reactions – play a key role in this transition. PETRA IV can assist in analysing such chemical helpers in more detail and thus improving them.

One of the visions for the future is to remove large amounts of CO₂ from the air and use it as a starting material for chemical reactions, for example to produce ethanol. In principle, this is already possible today with the help of catalysts. However, at the moment the reactions produce not only the desired ethanol, but also other substances that then have to be laboriously separated from the ethanol. Catalysts are therefore wanted that are considerably more selective and only favour the desired reaction to ethanol, but not other reactions.

Cheaper production of green hydrogen

Catalysts are also central to the production of green hydrogen in electrolysers – electrolysers are devices that allow water molecules to be split with the help of electricity. Until now, this reaction, known as catalysis, has often relied on comparatively expensive chemicals, such as iridium oxide. If other, cheaper materials could be used instead, hydrogen production would become cheaper. The useful life of the catalysts is also considered to be in need of improvement. The longer they last, the more cost-effective green hydrogen production becomes for industry.

In order to understand catalysts better and to specifically optimise them, scientists are investigating them with powerful X-ray sources such as PETRA III. This allows their exact molecular structure to be established in detail, for example. What remains limited, however, is the possibility of tracking the way these chemical helpers act and observing them at work, so to speak. PETRA IV will provide that opportunity. “In our experiments, we usually work with very small sample quantities,” explains Beatriz Roldán Cuenya, director at the Fritz Haber Institute in Berlin. “To understand how the catalysts behave, we excite them with energy and watch how they respond.” For this research, the Max Planck Institute is planning a new beamline, which will initially be set up at PETRA III and later continue to operate at PETRA IV.

To achieve the highest possible accuracy, a high temporal resolution is needed – that is to say, short exposure times in the range of one millisecond.

“It will take the high brilliance of PETRA IV before we can make fast enough measurements to observe the behaviour of the catalysts in greater detail,” says Beatriz Roldán Cuenya.