Nav: Home

Chemists ID catalytic 'key' for converting CO2 to methanol

March 23, 2017

UPTON, NY - Capturing carbon dioxide (CO2) and converting it to useful chemicals such as methanol could reduce both pollution and our dependence on petroleum products. So scientists are intensely interested in the catalysts that facilitate such chemical conversions. Like molecular dealmakers, catalysts bring the reacting chemicals together in a way that makes it easier for them to break and rearrange their chemical bonds. Understanding details of these molecular interactions could point to strategies to improve the catalysts for more energy-efficient reactions.

With that goal in mind, chemists from the U.S. Department of Energy's Brookhaven National Laboratory and their collaborators just released results from experiments and computational modeling studies that definitively identify the "active site" of a catalyst commonly used for making methanol from CO2. The results, published in the journal Science, resolve a longstanding debate about exactly which catalytic components take part in the chemical reactions-and should be the focus of efforts to boost performance.

"This catalyst-made of copper, zinc oxide, and aluminum oxide-is used in industry, but it's not very efficient or selective," said Brookhaven chemist Ping Liu, the study's lead author, who also holds an adjunct position at nearby Stony Brook University (SBU). "We want to improve it, and get it to operate at lower temperatures and lower pressures, which would save energy," she said.

But prior to this study, different groups of scientists had proposed two different active sites for the catalyst-a portion of the system with just copper and zinc atoms, or a portion with copper zinc oxide.

"We wanted to know which part of the molecular structure binds and breaks and makes bonds to convert reactants to product-and how it does that," said co-author Jose Rodriguez, another Brookhaven chemist associated with SBU.

To find out, Rodriguez performed a series of laboratory experiments using well-defined model catalysts, including one made of zinc nanoparticles supported on a copper surface, and another with zinc oxide nanoparticles on copper. To tell the two apart, he used an energetic x-ray beam to zap the samples, and measured the properties of electrons emitted. These electronic "signatures" contain information about the oxidation state of the atoms the electrons came from-whether zinc or zinc oxide.

Meanwhile Liu, Jingguang Chen of Brookhaven Lab and Columbia University, and Shyam Kattel, the first author of the paper and a postdoctoral fellow co-advised by Liu and Chen, used computational resources at Brookhaven's Center for Functional Nanomaterials (CFN) and the National Energy Research Scientific Computing Center (NERSC)-two DOE Office of Science User Facilities-to model how these two types of catalysts would engage in the CO2-to-methanol transformations. These theoretical studies use calculations that take into account the basic principles of breaking and making chemical bonds, including the energy required, the electronic states of the atoms, and the reaction conditions, allowing scientists to derive the reaction rates and determine which catalyst will give the best rate of conversion.

"We found that copper zinc oxide should give the best results, and that copper zinc is not even stable under reaction conditions," said Liu. "In fact, it reacts with oxygen and transforms to copper zinc oxide."

Those predictions matched what Rodriguez observed in the laboratory. "We found that all the sites participating in these reactions were copper zinc oxide," he said.

But don't forget the copper.

"In our simulations, all the reaction intermediates-the chemicals that form on the pathway from CO2 to methanol-bind at both the copper and zinc oxide," Kattel said. "So there's a synergy between the copper and zinc oxide that accelerates the chemical transformation. You need both the copper and the zinc oxide."

Optimizing the copper/zinc oxide interface will become the driving principal for designing a new catalyst, the scientists say.

"This work clearly demonstrates the synergy from combining theoretical and experimental efforts for studying catalytic systems of industrial importance," said Chen. "We will continue to utilize the same combined approaches in future studies."

For example, said Rodriguez, "We'll try different configurations of the atoms at the copper/zinc oxide interface to see how that affects the reaction rate. Also, we'll be going from studying the model system to systems that would be more practical for use by industry."

An essential tool for this next step will be Brookhaven's National Synchrotron Light Source II (NSLS-II), another Office of Science User Facility. NSLS-II produces extremely bright beams of x-rays-about 10,000 times brighter than the broad-beam laboratory x-ray source used in this study. Those intense x-ray beams will allow the scientists to take high-resolution snapshots that reveal both structural and chemical information about the catalyst, the reactants, and the chemical intermediates that form as the reaction occurs.

"And we'll continue to expand the theory," said Liu. "The theory points to the mechanistic details. We want to modify interactions at the copper/zinc oxide interface to see how that affects the activity and efficiency of the catalyst, and we'll need the theory to move forward with that as well."
An additional co-author, Pedro Ramírez of Universidad Central de Venezuela, made important contributions to this study by helping to test the activity of the copper zinc and copper zinc oxide catalysts.

This research was supported by the DOE Office of Science.

Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.

Media contacts: Karen McNulty Walsh, (631) 344-8350, or Peter Genzer, (631) 344-3174

DOE/Brookhaven National Laboratory

Related Zinc Articles:

Tackling iron and zinc deficiencies with 'better' bread
The health effects of zinc and iron deficiencies can be devastating, particularly in developing countries.
Zinc's negative effects on mineral digestibility can be mitigated, study shows
Researchers at the University of Illinois have shown that a common strategy for reducing postweaning digestive problems in pigs may have negative effects on calcium and phosphorus digestibility, and are suggesting management practices to counteract the effects.
Zinc may hold key to fighting liver disease
New research from Sydney's Westmead Institute for Medical Research highlights the potential for zinc to be used as a simple and effective therapeutic against viral infections such as hepatitis C and influenza.
Zinc oxide: It's not just for sunscreen and diaper cream!
For many, zinc oxide conjures images of bright stripes down lifeguards' noses.
Common cold duration is shortened similarly by zinc acetate and zinc gluconate lozenges
There is no significant difference between zinc acetate lozenges and zinc gluconate lozenges regarding their efficacy in shortening the duration of common colds according to a meta-analysis published in Journal of the Royal Society of Medicine Open.
Zinc supply affects cardiac health
In addition to essential metabolic functions, the level of zinc in the body also affects the heart muscle.
Better learning through zinc?
Zinc is a vital micronutrient involved in many cellular processes: For example, in learning and memory processes, it plays a role that is not yet understood.
Zinc: A surprise target in regenerating the optic nerve after injury
For more than two decades, researchers have tried to regenerate the injured optic nerve using different growth factors and/or agents that overcome natural growth inhibition.
Here's how your body transports zinc to protect your health
Researchers have, for the first time, created detailed blueprints of the molecular moving vans that ferry this important mineral everywhere it's needed through the blood.
Zinc lozenges help most patients recover earlier from the common cold
Zinc acetate lozenges may reduce the duration of the common cold by nearly 3 days, according to a recent analysis.

Related Zinc Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#532 A Class Conversation
This week we take a look at the sociology of class. What factors create and impact class? How do we try and study it? How does class play out differently in different countries like the US and the UK? How does it impact the political system? We talk with Daniel Laurison, Assistant Professor of Sociology at Swarthmore College and coauthor of the book "The Class Ceiling: Why it Pays to be Privileged", about class and its impacts on people and our systems.