5 November 2018

Differences clear at a glance

Fluorescent ‘breathalyzer’ makes optimisation of catalysts much easier

Dr. Gareth Whiting bij de 'pastamachine' voor katalysatoren

A breath test instead of a blood test. That’s how much easier it is to use the test for industrial catalysts developed by chemists at Utrecht University. The test uses fluorescent molecules to literally show whether catalyst 1, 2, or 3 works better than the others. This makes it much easier to work on improving the catalysts, which allows production processes in the chemical industry to become increasingly more sustainable. The researchers, under the leadership of Prof. Bert Weckhuysen, will publish their results in Nature Chemistry of 5 November.

In their research, the chemists from Utrecht studied the sustainable production of methanol, one of the building blocks for products such as plastics. Sustainable methanol can be synthesised from CO2 and hydrogen gas produced using wind- or solar energy or household waste. The catalyst is needed to ensure that the reaction produces as much methanol and as few by-products as possible, at the ideal temperature. The catalyst’s composition and porousness are important aspects of the process, but so is its shape.

Pasta machine

“Scientists study catalysts in their powder form, but chemical plants use catalysts in their shaped form, so we wanted to find a method that we could use to study such catalyst bodies in detail”, explains Bert Weckhuysen, Professor of Catalysis, Energy, and Sustainability at Utrecht University. To that end, the researchers brought a piece of equipment akin to a ‘pasta machine’ into the lab, to produce catalysts in a variety of shapes and sizes.

I believe it’s important to tie advanced science to day-to-day practice. Only then can we actually make progress when it comes to issues such as more sustainable production of materials and energy.
Prof. Bert Weckhuysen, Universiteit Utrecht

Inspiration from Biology

Prof. Weckhuysen found inspiration for studying the effects of the various shapes among his colleagues at the Department of Biology. They study cells by ‘colouring’ parts of the cells with fluorescent molecules. Under a fluorescence microscope, they can clearly see where the components are located and how they move through the cell. Weckhuysen and his colleagues now use the same technique by inserting fluorescent molecules into the catalyst and examining the results under a fluorescence microscope.

Fluorescence microscopy images show the effects of various shapes on catalyst activity

At a glance

“You can see at a glance what effect different shapes, dimensions and compositions of the catalyst can have”, illustrates Dr. Gareth Whiting, lead author of the publication. Whiting produced an entire series of catalysts that differed in shape, composition, and thickness. He then tested how well they functioned in converting the raw materials into methanol using the fluorescent molecules. Under a microscope, he could see how well the molecules reached the locations in the catalyst particles where the chemical reaction takes place. The methanol yield also indicated how effective the catalyst particles were.

Surprisingly easy

“These results were surprisingly easy to explain and predict using fluorescent probe accessibility models”, Whiting explains. “In doing so, we’ve proven that our research model is extremely robust. Producers and users of catalysts now have a new, fast, and easy way to see whether changes to the recipe or shape of a catalyst have positive or negative effects.”

Different perspective

Bert Weckhuysen’s lab is known for the highly advanced techniques it develops to examine catalysts during a chemical reaction. “But I believe it’s important to tie advanced science to day-to-day practice”, says Weckhuysen. “Only then can we actually make progress when it comes to issues such as more sustainable production of materials and energy. Plus, it’s just so much fun to work on things from a completely different perspective.”

Publication

Visualising pore architecture and molecular transport boundaries in catalyst bodies with fluorescent nanoprobes
Gareth T. Whiting*, Nikolaos Nikolopoulos, Ioannis Nikolopoulos, Abhishek Dutta Chowdhury, Bert M. Weckhuysen*
Nature Chemistry, 5 November 2018, DOI: 10.1038/s41557-018-0163-z
*All authors are affiliated with Utrecht University.

This project was partly funded by the The Netherlands Organisation for Scientific Research (NWO).

More research from the group of Bert Weckhuysen