CO2 – Lightsources.org

A Close Look at a Copper-Titanium Catalyst Under CO2 Hydrogenation

2025/01/162025/01/20

A major facet of transitioning from fossil fuels to green and renewable energy solutions involves the removal, capture and storage of carbon dioxide (CO₂) from the environment. One method is by CO₂ hydrogenation, which requires a catalyst to spur the reaction, frequently including metal-oxide catalysts in which metal-support interactions (MSIs) play an important role.

Researchers from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, Stony Brook University, DOE’s Argonne National Laboratory and several other institutions used a suite of in situ techniques to study the behavior and structural and chemical properties of a Cu@TiO_x core@shell catalyst under CO₂ hydrogenation. Their work was published in ACS Catalysis.

In a core@shell structure, one type of active system (the core) is encapsulated by a shell of a different material to enhance catalytic performance. These experiments focused on an inverse oxide/metal catalyst configuration using a copper nanowire core with a titanium oxide (titania) shell. Such catalysts have been shown to offer improved stability and activity over the conventional metal/oxide arrangement.

Through the use of an entire range of in situ characterization techniques – including time-resolved experiments with X-ray absorption spectroscopy (XAS), ambient pressure X-ray photoelectron spectroscopy (AP-XPS), environmental transmission electron microscopy (E-TEM), and X-ray diffraction at the 17-BM-B beamline of the Advanced Photon Source, a DOE Office of Science user facility at Argonne – the investigators sought to achieve a comprehensive understanding of the structure and behavior of the Cu@TiO_x catalyst under CO₂ activation and hydrogenation, a functional picture that cannot be obtained with typical steady state studies.

The dynamic characteristics of this catalyst system became immediately evident even during the standard pretreatment used for CO₂ hydrogenation, when the H₂ pretreatment at temperatures of above 250 degrees Celsius resulted in cracking of the titania shell and migration of Cu particles from the core to the top of the oxide shell. This, along with other configuration changes, was caused by metal-support interactions. The migrating Cu particles are about 20-40 nm in diameter and are speckled with clusters of TiO_x and Cu-Ti-O_x. With this altered structure, the system displayed highly dynamic yet wholly reversible catalytic characteristics that were dependent on temperature and chemical environment.

Read more on Argonne website

Image: E-TEM that match with the XRD results.

Trapping and storing carbon dioxide underground

2024/11/062024/11/14

A team led by the University of Oslo in Norway, in collaboration with the University of Maryland in USA, is investigating how to massively store carbon dioxide (CO2) underground by copying nature. Through a chemical reaction, carbon dioxide can be trapped naturally inside the Earth’s subsurface and stored as solid minerals, called carbonates. The researchers are now carrying out experiments at the ESRF with the aim to accelerate such a process.

Carbon dioxide levels in the atmosphere are higher than ever, mainly due to the burning of fossil fuels and other anthropogenic activities. This, in turn, increases global temperatures and impacts sea levels and the ocean ecosystems.

A potential solution to this crisis would be to trap and store CO₂ underground as solid minerals, which is a natural process that occurs over long periods thanks to the reaction of CO₂ with rocks in the Earth’s crust and mantle.

Scientists have been studying the injection of CO₂in the subsurface for years. For example, in Sleipner, in the North Sea, millions of tons of carbon dioxide have been injected into a sandstone geological reservoir in the past fifteen years, where CO₂ is stored in liquid form. CO₂ can also be stored in solid form through mineralization processes, minimising the risk of leakage. Small-scale ongoing projects, such as Carbfix in Iceland, show promising results but questions of efficiency remain.

“The natural process is very effective but too slow, so we wonder whether we could somehow accelerate it so that large quantities of CO₂ could be injected underground, without leakage”, explains François Renard, director of the Njord Centre at the University of Oslo and ESRF user.

The natural process

Atmospheric CO₂ and water from precipitations naturally react with rocks present at the Earth’s surface – this process is called weathering. Some of these rocks have been produced by volcanic activity (basalts in Iceland) or were exhumed to the Earth’s surface from the mantle (peridotites). When reacting with CO₂ and water, they may dissolve partially over geological time scales, liberating magnesium, iron, and calcium ions that can bind with carbon dioxide, in a process called mineral carbonation, which converts CO₂ into minerals. The end product is a calcium, iron or magnesium carbonate, which are stable minerals that effectively trap carbon dioxide into a solid form.

Renard and his team are focusing on storing CO₂ in basaltic and peridotite rocks, rich in magnesium and calcium, as they are the most efficient environments for it due to their high reactivity. They make up about 70% of the Earth’s surface and are responsible for 1/3 of the trapping of CO₂ from the atmosphere through weathering. Estimates suggest that mid-ocean ridges worldwide can store up to 100,000 Gt of CO₂. This is more than 2000 times the annual global emissions of CO₂.

Once in the basaltic or peridotite rocks, the CO₂ quickly reacts with the divalent cations (Ca²⁺, Mg²⁺, and Fe²⁺) from dissolving minerals in the rock and form carbonate minerals. In comparison, it might take several tens of thousands of years for significant amounts of CO₂ to mineralize in a sandstone reservoir. After it becomes a mineral, the carbon will not move over geological timescales.

Carbonation at the ESRF

The team is focused on studying how basalts and peridotites can host large quantities of flows of carbon dioxide mixed with water, which will react with the rock to produce carbonate minerals.

Read more on ESRF website

Scientists show the first step of turning CO2 into fuel in two very different ways

2021/08/042021/08/19

Their work aims to bridge two approaches to driving the reaction – one powered by heat, the other by electricity – with the goal of discovering more efficient and sustainable ways to convert carbon dioxide into useful products.

Virtually all chemical and fuel production relies on catalysts, which accelerate chemical reactions without being consumed in the process. Most of these reactions take place in huge reactor vessels and may require high temperatures and pressures.

Scientists have been working on alternative ways to drive these reactions with electricity, rather than heat. This could potentially allow cheap, efficient, distributed manufacturing powered by renewable sources of electricity.

But researchers who specialize in these two approaches – heat versus electricity – tend to work independently, developing different types of catalysts tailored to their specific reaction environments.

Why having your head in the clouds could be a really good thing

2019/04/152019/04/17

The ATMOS research group in the NANOMO unit, led by Nønne Prisle, Associate Professor at the University of Oulu, are trying to find out what kind of chemistry is happening in cloud droplets and tiny nanometer-sized aerosol particles in the atmosphere. This knowledge could eventually, hopefully, give us more accurate theoretical models to understand the ongoing climate change.
– The only thing that can halter climate change is to stop emitting CO₂. Nønne Prisle is very, very clear on that. Even so, she says, if we want to take any other step to try to counter climate change, we really need to know what’s going on in the clouds since these processes could be quite critical.
The ATMOS team are using the beamline HIPPIE at MAX IV being so-called commissioning experts, which means that the experiment is done both to provide useful data but also to verify the capacity and capability of the beamline experimental station.

Image: From left to right: Robert Seidel, Helmholtz Zentrum Berlin; Nønne Prisle, Kamal Raj and Jack Lin, University of Oulu at the HIPPIE beamline.

Putting CO2 to a good use

2018/04/302018/05/02

One of the biggest culprits of climate change is an overabundance of carbon dioxide in the atmosphere.

As the world tries to find solutions to reverse the problem, scientists from Swansea University have found a way of using CO2 to create ethylene, a key chemical precursor. They have used ID03 to test their hypotheses.

Carbon dioxide is essential for the survival of animals and plants. However, people are the biggest producers of CO₂ emissions. The extensive use of fossil fuels such as coal, oil, or natural gas has created an excess of CO₂ in the atmosphere, leading to global warming. Considerable research focuses on capturing and storing harmful carbon dioxide emissions. But an alternative to expensive long-term storage is to use the captured CO₂ as a resource to make useful materials.