7 things you might not know about catalysis

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Computer modeling produces both prospects for better catalysts and beautiful images, like this model of a platinum catalyst interacting with oxygen atoms (red) and hydrogen atoms (white). Credit: Image by Rees Rankin, Center for Nanoscale Materials.

Catalysts are one of those things that few people think much about, beyond maybe high school chemistry, but they make the world go round. The catalysts are all around us.

Almost everything in your daily life depends on catalysts: cars, Post-It notes, laundry detergent, beer. All the parts of your sandwich: bread, cheddar cheese, roast turkey. Catalysts break down the pulp to produce the smooth paper for your magazine. They clean your contact lenses every night. They turn milk into yogurt and oil into plastic milk jugs, CDs and bicycle helmets.

What is catalysis?

Catalysts speed up a chemical reaction by reducing the amount of energy you need to start one. Catalysis is the backbone of many industrial processes, which use chemical reactions to turn raw materials into useful products. Catalysts are an integral part of the manufacture of plastics and many other manufactured items.

Even the human body works on catalysts. Many of the proteins in your body are actually catalysts called enzymes, which do everything from creating signals that move your limbs to digesting food. They really are a fundamental part of life.

Jeff Greeley, Stefan Vajda and Larry Curtiss

Argonne scientists Jeff Greeley, Stefan Vajda and Larry Curtiss (left to right) are working to create new catalysts, like this one that reduces harmful by-products in manufacturing processes.

Small things can have big results.

In most cases, you only need a tiny amount of catalyst to tell the difference. Even the size of the catalyst particle can change the way a reaction proceeds. Last year, a team in Argonne including materials scientist Larry Curtiss found that a silver catalyst is better at its task when found in nanoparticles a few atoms wide. (The catalyst converts propylene to propylene oxides, which is the first step in the manufacture of antifreeze and other products.)

It can make things greener.

Industrial manufacturing processes for plastics and other essential items often produce nasty by-products that can pose risks to human health and the environment. Better catalysts can help solve this problem. For example, the same silver catalyst actually produces fewer toxic byproducts, making the entire reaction more environmentally friendly.

Basically, a catalyst is a way to save energy. And the application of catalysts on a large scale could save the world from a parcel of energy. Three percent of all the energy used in the United States each year is used to convert ethane and propane to alkenes, which are used to make plastics, among other things. That’s the equivalent of over 500 million barrels of gasoline.

Catalysts are also the key to unlocking biofuels. All biomass (corn, switchgrass, trees) contains a tough compound called cellulose, which must be broken down to make fuel. Finding the perfect catalyst to break down cellulose would make biofuels cheaper and more viable as a renewable energy source.

Often, we don’t know why they work.

The precise reasons why catalysts work often remain a mystery to scientists. Curtiss works in the field of computational catalysis: he uses computers to tackle the complex interplay of physics, chemistry and mathematics that explains how a catalyst works.

Once they understand the process, scientists can try to build a catalyst that works even better by simulating how different materials might work instead. The potential configurations for new catalysts can run in thousands of combinations, which is why supercomputers are the best to handle them.

When Edison was building the bulb, he tested literally hundreds of different filaments (probably also the patience of his lab assistants) before discovering the charred filament. By taking advantage of supercomputers and modern technology, scientists can accelerate years of testing and spending to achieve breakthroughs.

Curtiss runs simulations on Argonne’s Blue Gene / P supercomputer to design possible new catalysts. “As supercomputers got faster, we were able to do things that we could never have done 10 years ago,†he said.

They could be essential for the next big battery revolution.

New efficient lithium-ion batteries have helped transform bulky car phones into the slim and sleek cell phones and laptops available today. But scientists are already on the hunt for the next battery revolution, one that could one day make a battery light and powerful enough to travel 800 miles straight in a car. A promising idea is lithium-air batteries, which use oxygen from the air as the main component. But this new battery will require a complete overhaul of internal chemistry, and it will need a powerful new catalyst to make it work. A lithium-air battery works by combining atoms of lithium and oxygen, then separating them, over and over again. This is a tailor-made situation for a catalyst, and a good solution would speed up the reaction and make the battery more efficient.

How to make a new catalyst?

Understanding the chemistry behind the reactions is the first step; scientists can then use modeling to design potential new catalysts and have them tested in the lab. But this first step is difficult unless you can go down to the atomic level to see what happens during a reaction. This is where large scientific facilities like Argonne’s Advanced Photon Source (APS) shine.

At APS, scientists can use America’s brightest x-rays to track reactions in real time. At the lab’s electron microscopy center, researchers take pictures of atoms as they react. Curtiss and the team used both in their search for better catalysts.

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