By U.S. Department of Energy May 18, 2021
A real catalyst (background image) and a schematic of a catalytic step (foreground image). Reacting molecules (at left) acquire energy to climb the energy barrier and convert into product molecules (at right). Credit: Image courtesy of Argonne National Laboratory
A catalyst is a substance that speeds up a chemical reaction, or lowers the temperature or pressure needed to start one, without itself being consumed during the reaction. Catalysis is the process of adding a catalyst to facilitate a reaction.
During a chemical reaction, the bonds between the atoms in molecules are broken, rearranged, and rebuilt, recombining the atoms into new molecules. Catalysts make this process more efficient by lowering the activation energy, which is the energy barrier that must be surmounted for a chemical reaction to occur. As a result, catalysts make it easier for atoms to break and form chemical bonds to produce new combinations and new substances.
Using catalysts leads to faster, more energy-efficient chemical reactions. Catalysts also have a key property called selectivity, by which they can direct a reaction to increase the amount of desired product and reduce the amount of unwanted byproducts. They can produce entirely new materials with entirely new potential uses.
Over the past several decades, scientists have developed increasingly specialized catalysts for essential real-world applications. In particular, powerful catalysts have transformed the chemical industry. These advances have led to biodegradable plastics, new pharmaceuticals, and environmentally safer fuels and fertilizers.
Fast Facts
- Humans have been using catalysts for thousands of years. For example, the yeast we use to make bread contains enzymes, which are natural catalysts that aid the conversion of flour into bread.
- The 2005 Nobel Prize in Chemistry was awarded to three researchers (Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock) for their work on metathesis catalysts. Drs. Grubbs and Schrock were funded in part by DOE for their Nobel-Prize research. Dr. Schrock continues to be funded by DOE.
- The 2018 Nobel Prize in Chemistry was awarded to Frances H. Arnold for her pioneering work to direct the evolution of enzymes for applications such as renewable fuels that are environmentally harmless. She is funded in part by DOE.
- Visit Argonne National Lab for seven more things you may not know about catalysis.
DOE Office of Science: Contributions to Catalyst Research
The Department of Energy (DOE) Office of Science Basic Energy Sciences program actively supports basic research on catalysts. DOE focuses on the design of new catalysts and on the use of catalysts to control chemical transformations at the molecular and sub-molecular levels. DOE research emphasizes understanding these reactions and how to make them more efficient and targeted. DOE’s overarching goal is to develop new concepts in catalysis and new catalysts to help industry produce fuels and chemicals from fossil and renewable raw materials more efficiently and sustainably. This research is helping advance solar fuels, which are fuels companies make using the sun and common chemicals like carbon dioxide and nitrogen. This research is also creating advanced methods for transforming discarded plastic into new products.
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 paper pulp to produce the smooth paper in your magazine. They clean your contact lenses every night. They turn milk into yogurt and petroleum into plastic milk jugs, CDs and bicycle helmets.
What is catalysis?
Catalysts speed up a chemical reaction by lowering the amount of energy you need to get one going. Catalysis is the backbone of many industrial processes, which use chemical reactions to turn raw materials into useful products. Catalysts are integral in making plastics and many other manufactured items.
Even the human body runs on catalysts. Many proteins in your body are actually catalysts called enzymes, which do everything from creating signals that move your limbs to helping digest your food. They are truly a fundamental part of life.
Small things can have big results.
In most cases, you need just a tiny amount of a catalyst to make a difference. Even the size of the catalyst particle can change the way a reaction runs. Last year, an Argonne team including materials scientist Larry Curtiss found that one silver catalyst is better at its task when it’s in nanoparticles just a few atoms wide. (The catalyst turns propylene into propylene oxides, which is the first step in making antifreeze and other products.)
It can make things greener.
Industrial manufacturing processes for plastic and other essential items often produce nasty by-products which can pose hazards to human health and the environment. Better catalysts can help solve that problem. For example, the same silver catalyst actually produces fewer toxic by-products—making the whole reaction more environmentally friendly.
At its heart, a catalyst is a way to save energy. And applying catalysts on a grand scale could save the world a lot of energy. Three percent of all of the energy used in the U.S. every year goes into converting ethane and propane into alkenes, which are used to make plastics, among other things. That’s the equivalent of more than 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 has to be broken down to make fuel. Finding the perfect catalyst to disintegrate cellulose would make biofuels cheaper and more viable as a renewable energy source.
Often, we have no idea why they work.
The precise reasons why catalysts work are often still a mystery to scientists. Curtiss works in computational catalysis: using computers to tackle the complicated interplay of physics, chemistry and math that explains how a catalyst operates.
Once they’ve figured out the process, scientists can try to build a catalyst that works even better by simulating how different materials might work instead. Potential configurations for new catalysts can run to thousands of combinations, which is why supercomputers are best at dealing with them.
When Edison was building the light bulb, he tested literally hundreds of different filaments (likely testing the patience of his lab assistants as well) before discovering the carbonized filament. By taking advantage of supercomputers and modern technology, scientists can speed up the years of testing and expense to get to breakthroughs.
Curtiss runs simulations on Argonne’s Blue Gene/P supercomputer to design possible new catalysts. “As supercomputers have gotten faster, we’ve been able to do things we’d never have been able to do 10 years ago,” he said.
They could be essential for the next big revolution in batteries.
Newly efficient lithium-ion batteries helped turn clunky car phones into the slim, elegant cell phones and laptops available today. But scientists are already searching for the next revolution in batteries—one that could someday make a battery light and powerful enough to take a car 500 miles at a go. A promising idea is lithium-air batteries, which use oxygen from the air as a primary component. But this new battery will require totally revamping the internal chemistry, and it will need a powerful new catalyst to make it work. A lithium-air battery works by combining lithium and oxygen atoms and then breaking them apart, over and over. That is a situation tailor-made for a catalyst, and a good one would make the reaction faster and make the battery more efficient.
How do you make a new catalyst?
Understanding the chemistry behind reactions is the first step; then scientists can use modeling to design potential new catalysts and have them tested in the lab. But that first step is difficult unless you can get down to the atomic level to see what is happening during a reaction. This is where big scientific facilities like Argonne’s Advanced Photon Source (APS) shine.
At the APS, scientists can use the brightest X-rays in the United States to track the reactions in real time. At the laboratory’s Electron Microscopy Center, researchers take photos of the atoms while they react. Curtiss and the team have used both of these in their search for better catalysts.