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Age-Old Phenomenon that Doesn’t Actually Exist in Catalysis.

catálisis

Catalysis is responsible for 95% of industrial chemical processes, and directly affects more than 1/3 of the world’s gross domestic product (GDP).

What is catalysis?

It is the process increasing the rate of a chemical reaction; “helping it” – achieved by means of a catalyst – a “starter”.

The catalyst is not consumed by the reaction, nor changed by it, and can keep on “helping” indefinitely (although in practice catalysts can deactivate in seconds to years).

It can be likened to a bossy matchmaker, bringing couples together.

Many catalysts are made up of nanoparticles on a support, which can have varied structures.

A smaller particle has more irregular surfaces, with peaks and valleys, and displays more atoms “sticking out”. A larger particle would have more flat areas.

The nanoparticle’s shape and size should affect how effective they are at catalyzing a reaction, depending on whether the reaction needs the peaks and valleys or the flat surfaces.

Except sometimes the shape appears to have absolutely no effect – no matter whether the particles are big or small, the reaction occurs at the same rate.

This is called “structure insensitivity”. It is a phenomenon that is empirically observed, but for a long time it remained unexplained. It had already been theoretically accepted that it should not exist.

Now, Prof. Charlotte Vogt from the Schulich Faculty of Chemistry at the Technion, together with an international team of scientists, has found the answer.

Prof. Vogt used advanced characterization methods, including particle accelerators and quick spectroscopy to discover that the reactions indeed only appear to be structure insensitive.

In truth, what happens is that the catalyst nanoparticle undergoes rapid restructuring. It changes its shape, and displays not the expected “flat surfaces”, but peaks and valleys, leaving only specific reactive sites exposed.

The process is so fast, that without the novel technology, and smart experimental design, it could not have been observed.

The study was a collaboration between the Technion, Utrecht University, Eindhoven University, Oak Ridge National Laboratory, Stony Brook University, and the Paul Scherrer Institute. It was recently published in Nature Communications.

Catalysis plays such an important role in nearly every industry; it is easy to see how understanding catalysts and improving them can have a significant impact.

Prof. Vogt explains: “I believe the key to a greener, more sustainable future lies in better catalysts. Imagine, for example, turning CO2 into useful compounds. It sounds like science fiction.

The truth is, such a process is theoretically possible, but it is not yet energy efficient.

Right now, it would create more pollution than it would save.

If, however, we could lower the amount of energy required, or if we would be able to tune the catalyst to make specific products, if we could find catalysts that would make these things easier, suddenly it would become feasible.

Remember, acid rain used to be a problem we talked about even two decades ago, and now we no longer do. It was solved, using catalysts.”

 

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