Oceans emit sulfur and cool the climate more than previously thought

University of East Anglia

 

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Scientists have managed to quantify methanethiol emissions in the oceans on a global scale for the first time.

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Credit: Rafel Simó (ICM-CSIC)

Researchers have quantified for the first time the global emissions of a sulfur gas produced by marine life, revealing it cools the climate more than previously thought, especially over the Southern Ocean.

The study, published in the journal Science Advances, shows that the oceans not only capture and redistribute the sun's heat, but produce gases that make particles with immediate climatic effects, for example through the brightening of clouds that reflect this heat.

It broadens the climatic impact of marine sulfur because it adds a new compound, methanethiol, that had previously gone unnoticed. Researchers only detected the gas recently, because it used to be notoriously hard to measure and earlier work focussed on warmer oceans, whereas the polar oceans are the emission hotspots.

The research was led by a team of scientists from the Institute of Marine Sciences (ICM-CSIC) and the Blas Cabrera Institute of Physical Chemistry (IQF-CSIC) in Spain. They included Dr Charel Wohl, previously at ICM-CSIC and now at the University of East Anglia (UEA) in the UK.

Their findings represent a major advance on one of the most groundbreaking theories proposed 40 years ago about the role of the ocean in regulating the Earth's climate.

This suggested that microscopic plankton living on the surface of the seas produce sulfur in the form of a gas, dimethyl sulphide, that once in the atmosphere, oxidizes and forms small particles called aerosols.

Aerosols reflect part of the solar radiation back into space and therefore reduce the heat retained by the Earth. Their cooling effect is magnified when they become involved in making clouds, with an effect opposite to, but of the same magnitude as, that of the well-known warming greenhouse gases, such as carbon dioxide or methane.

The researchers argue that this new work improves our understanding of how the climate of the planet is regulated by adding a previously overlooked component and illustrates the crucial importance of sulfur aerosols. They also highlight the magnitude of the impact of human activity on the climate and that the planet will continue to warm if no action is taken.

Dr Wohl, of UEA’s Centre for Ocean and Atmospheric Sciences and one of the lead authors, said: “This is the climatic element with the greatest cooling capacity, but also the least understood. We knew methanethiol was coming out of the ocean, but we had no idea about how much and where. We also did not know it had such an impact on climate.

“Climate models have greatly overestimated the solar radiation actually reaching the Southern Ocean, largely because they are not capable of correctly simulating clouds. The work done here partially closes the longstanding knowledge gap between models and observations.”

With this discovery, scientists can now represent the climate more accurately in models that are used to make predictions of +1.5 ºC or +2 ºC warming, a huge contribution to policy making.

“Until now we thought that the oceans emitted sulfur into the atmosphere only in the form of dimethyl sulphide, a residue of plankton that is mainly responsible for the evocative smell of shellfish,” said Dr Martí Galí, a researcher at the ICM-CSIC and another of the main study authors.

Dr Wohl added: “Today, thanks to the evolution of measurement techniques, we know that plankton also emit methanethiol, and we have found a way to quantify, on a global scale, where, when and in what quantity this emission occurs.

“Knowing the emissions of this compound will help us to more accurately represent clouds over the Southern Ocean and calculate more realistically their cooling effect.”

The researchers gathered all the available measurements of methanethiol in seawater, added those they had made in the Southern Ocean and the Mediterranean coast, and statistically related them to seawater temperature, obtained from satellites.

This allowed them to conclude that, annually and on a global average, methanethiol increases known marine sulfur emissions by 25%.

“It may not seem like much, but methanethiol is more efficient at oxidising and forming aerosols than dimethyl sulfide and, therefore, its climate impact is magnified,” said co-lead Dr Julián Villamayor, a researcher at IQF-CSIC.

The team also incorporated the marine emissions of methanethiol into a state-of-the-art climate model to assess their effects on the planet's radiation balance.

It showed the impacts are much more visible in the Southern Hemisphere, where there is more ocean and less human activity, and therefore the presence of sulfur from the burning of fossil fuels is lower.

The work was supported by funding from organisations including the European Research Council and Spanish Ministry of Science and Innovation.

‘Marine emissions of methanethiol increase aerosol cooling in the Southern Ocean’, Charel Wohl, Julián Villamayor and Martí Galí et al, is published in Science Advances on November 27.

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Journal

Science Advances

DOI

10.1126/sciadv.adq2465 

Article Title

Marine emissions of methanethiol increase aerosol cooling in the Southern Ocean

Article Publication Date

27-Nov-2024

PALEONTOLOGY

Fossil dung reveals clues to dinosaur success story

Uppsala University

 

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A duo of sauropodomorphs; one munching on the newly evolved plants in a wet Early Jurassic environment whilst the other is looking up as if there was something hiding in the vegetation. Illustration: Marcin Ambrozik.

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Credit: Marcin Ambrozik

In an international collaboration, researchers at Uppsala University have been able to identify undigested food remains, plants and prey in the fossilised faeces of dinosaurs. These analyses of hundreds of samples provide clues about the role dinosaurs played in the ecosystem around 200 million years ago. The findings have been published in the journal Nature.

“Piecing together ‘who ate whom’ in the past is true detective work,” says Martin Qvarnström, researcher at the Department of Organismal Biology and lead author of the study. “Being able to examine what animals ate and how they interacted with their environment helps us understand what enabled dinosaurs to be so successful.”

Palaeontologists from Uppsala University, in collaboration with researchers from Norway, Poland and Hungary, have examined hundreds of samples using advanced synchrotron imaging to visualise the hidden, internal parts of the fossilised faeces, known as coprolites, in detail. By identifying undigested food remains, plants and prey, they have recreated the structure of the ecosystems at the time when dinosaurs began their success story.

The study focused on a previously underexplored region, Polish Basin, located in the Late Triassic time in the in the northern parts of the then supercontinent Pangea. The researchers built up a comprehensive picture of the Triassic and Jurassic ecosystems (from about 230 to 200 million years ago) by combining the information from the coprolites with climate data and information from other fossils: plants, bite marks, vomit, footprints and bones.

“The research material was collected over a period of 25 years. It took us many years to piece everything together into a coherent picture,” says Grzegorz Niedźwiedzki, researcher at the Department of Organismal Biology and the study’s senior author. “Our research is innovative because we have chosen to understand the biology of early dinosaurs based on their dietary preferences. There were many surprising discoveries along the way.”

The coprolites contained remains of fish, insects, larger animals and plants, some of which were unusually well preserved, including small beetles and semi-complete fish. Other coprolites contained bones chewed up by predators that, like today’s hyenas, crushed bones to obtain salts and marrow. The contents of coprolites from the first large herbivorous dinosaurs, the long-necked sauropods, surprised the researchers. These contained large quantities of tree ferns, but also other types of plants, and charcoal. The palaeontologists hypothesise that charcoal was ingested to detoxify stomach contents, as ferns can be toxic to herbivores.

The research addresses a significant gap in current knowledge: the first 30 million years of dinosaur evolution during the Late Triassic period. Although much is known about their lives and extinction, the ecological and evolutionary processes that led to their rise are largely unexplored. The study results in a five-step model of dinosaur evolution that the researchers believe can explain global patterns.

The team emphasises that understanding how the first dinosaurs achieved their success can offer valuable insights into prehistoric ecosystems and evolutionary processes in general. The results show that dietary diversity and adaptability were crucial survival traits during the environmental changes of the Late Triassic.

“Unfortunately, climate change and mass extinctions are not just a thing of the past. By studying past ecosystems, we gain a better understanding of how life adapts and thrives under changing environmental conditions,” says Qvarnström.

“The way to avoid extinction is to eat a lot of plants, which is exactly what the early herbivorous dinosaurs did. The reason for their evolutionary success is a true love of green and fresh plant shoots,” Niedzwiedzki concludes.

s from a large fish with spiral gut (hence the spirals in the coprolite), showing fish scales indicative of diet. Illustration:  Martin Qvarnström

CaptionLarge coprolite with fish remains: A coprolite fragment densely packed with fish bones, likely produced by the phytosaur Paleorhinus. Illustration: Martin Qvarnström

Fossil faeces of the bone-crushing archosaur Smok, with a Smok reconstruction in the background. (IMAGE)

Uppsala University

Coprolite from Smok: Fossil faeces of the bone-crushing archosaur Smok, with a Smok reconstruction in the background. Illustration: Grzegorz Niedźwiedzki

Journal

Nature

DOI

10.1038/s41586-024-08265-4 

Article Title

Digestive contents and food webs record the advent of dinosaur supremacy

Article Publication Date

27-Nov-2024

World’s oldest lizard wins fossil fight

University of Bristol

 

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Photo of the inside of the skull and lower jaw on the right and CT scan of the outside of the same bones on the left image. The images show the left side of the skull and lower jaw

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Credit: 3D imagery by Sofia Chambi Trowell, photograph by David Whiteside

A storeroom specimen that changed the origins of modern lizards by millions of years has had its identity confirmed.

The tiny skeleton, unearthed from Triassic-aged rocks in a quarry near Bristol, is at least 205 million years old and the oldest modern-type lizard on record.

Recently, the University of Bristol team’s findings came under question, but fresh analysis, published today in Royal Society Open Science, proves that the fossil is related to modern anguimorphs such as anguids and monitors. The discovery shifts the origin of the whole lizard-snake group, called Squamata, back by 35 million years.

In the original study, Dr David Whiteside, Dr Sofia Chambi-Trowell and Professor Mike Benton, named the little critter Cryptovaranoides microlanius, meaning ‘hidden lizard, small butcher’ because of its identification as a lizard and its sharp teeth, probably used for cutting up prey animals for food. The Bristol team identified many anatomical features of the skull and skeleton that allowed them to place it well within Squamata, and even close to the Anguimorpha.

“We knew our paper would be controversial,” explained Dr Whiteside. “But we were confident that we had looked at every possible feature and compared it with everything we could.”

Professor Benton said: “We were therefore surprised, perhaps even shocked, that in 2023 another team of academics suggested that Cryptovaranoides was not a lizard or even a lizard relative, but in fact an archosauromorph, more closely related to crocodilians and dinosaurs.”

In checking their original work, and the questions posed in the rival paper, the Bristol team explored all the data, including the original specimen as well as the X-ray scans that show the details hidden within the rock. “We had the marvellous images from those CT scans as well as further access to the fossil which enabled us to check all their suggestions,” said Dr Chambi-Trowell. “We found that most of the concerns raised were wrong.”

Professor Benton added: “All the details of the skull, the jaws, the teeth, and the limb bones confirm that Cryptovaranoides is a lizard, not an archosauromorph.

“In our new paper, we provide great detail of every criticism made and we provide more photographs of the specimen and 3D images from the scans, so everyone can check the detail.”

Dr Whiteside concluded: “The result of all this had to be tested by a phylogenetic analysis.

“This is where we code hundreds of anatomical features in Cryptovaranoides and other modern and fossil lizards, as well as various archosauromorphs.

“We ran the analysis time after time, and it gave our original result, that the little Bristol reptile is indeed the world’s oldest modern-type lizard.”

The paper

Whiteside DI, Chambi-Trowell SAV, Benton MJ. 2024 Late Triassic †Cryptovaranoides microlanius is a squamate, not an archosauromorph. R. Soc. Open Sci. 11: 231874. https://doi.org/10.1098/rsos.231874

Life restoration of the earliest lizard, Cryptovaranoides microlanius 

Credit

Lavinia Gandolfi

Journal

Royal Society Open Science

Method of Research

Computational simulation/modeling

Subject of Research

Animals

Article Title

Cryptovaranoides microlanius is a squamate, not an archosauromorph

Article Publication Date

26-Nov-2024

 

Discovering the traits of extinct birds

Analysis by Utah biologists found birds endemic to islands, lacking flight, with large bodies and sharply angled wings were more likely to disappear first

University of Utah

 

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A critically endangered ‘Akikiki that study lead author Kyle Kittelberger photographed on Kauai in 2022.

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Credit: Kyle Kittelberger

Looking to inform the conservation of critically endangered bird species, University of Utah biologists completed an analysis identifying traits that correlate with all 216 bird extinctions since 1500.

Species most likely to go extinct sooner were endemic to islands, lacked the ability to fly, had larger bodies and sharply angled wings, and occupied ecologically specific niches, according to research published this month.

While some of these findings mirror previous research on extinct birds, they are the first to correlate bird traits with the timing of extinctions, said lead author Kyle Kittelberger, a graduate student in the School of Biological Sciences.

“I’ve been very interested in extinctions and understanding the species that we’ve lost and trying to get a sense of how we can use the past to better inform the present and future,” said Kittelberger, who is completing his dissertation on how the bodies and wings of certain species of migratory songbirds have changed in response to climate change.

His team’s analysis tapped into BirdBase, a dataset of ecological traits for the world’s 11,600+ bird species compiled by U biology professor Çağan Şekercioğlu and the Biodiversity and Conservation Ecology Lab at the U. The team simultaneously analyzed a broad range of biogeographical, ecological and life history traits previously associated with extinction and extinction risk for bird species that have gone extinct as well as those that lack recent confirmed sightings and have therefore disappeared.

“Importantly, we examine biological correlates of bird extinctions through the lens of when birds went extinct, providing a novel extinction timing element that helps better inform why birds with certain traits disappeared when they did,” Kittelberger wrote in a series of posts on X. By identifying traits that most predispose birds to extinction, the findings can help guide conservation efforts of hundreds of species that are at peril.

“One of the strengths of the approach that we use is we compared all of these traits simultaneously against each other, whereas a lot of previous studies in the literature just look at traits in isolation.”

While only around 2% of the world’s bird species have gone extinct since 1500, the year Kittelberger’s analysis begins, even more had already disappeared by then. Before 1500, however, there is not as reliable a record of the birds that went extinct and data on their traits and characteristics.

This timing coincides with the rise of scientific observation, resulting in a systematic documentation of plant and animal life. It is also the time when European exploration took off, leading to the disruption of ecosystems around the globe as a result of colonization and introduced species.

Today, 1,314 bird species are at risk of extinction, according to the IUCN Red List of Threatened Species, or about 12% of the total.

Many species, such as the ‘Akikiki (Oreomystis bairdi), endemic to the Hawaiian island of Kauai, are so rare that they are functionally extinct. Kittelberger photographed the pictured ‘Akikiki, also called Kauai’s creeper, in the Alaka‘i Wilderness Preserve in 2022, when it was believed around 70 or so remained in the wild; today, only one individual remains.

The proportion of 216 bird species globally extinct or likely lost since 1500 that were endemic to a region, found solely on islands, and were either flightless or partially flightless, as well as the breakdown of species by primary habitat or diet.

As with many other Hawaiian bird species, the main threat to the ’Akikiki comes in the form of introduced species, principally malaria-carrying mosquitoes and habitat-wrecking livestock, according to Hawaii’s Division of Forestry and Wildlife.

The single most critical trait associated with extinction is insularity, those species endemic to islands. Other traits that appear to increase extinction risk, such as body size, wing shape and ecological specialization, are also associated with island insularity.

Pacific islands are home to a vast array of endemic species, many of which are now on the IUCN list. No archipelago has seen more loss of avian biodiversity than Hawaii, which accounts for 34 post-1500 extinctions, according to the study.

The bird family that experienced the most extinctions is Rallidae, or rails, which are globally distributed medium-sized semi-amphibious bird species. This family lost 26 members, while the entire line of the Mohoidae family, small nectar-sipping songbirds commonly known as Hawaiian honeyeaters, is completely gone (the only bird family to go fully extinct in modern times). The family’s last member, the Kauai O’o (Moho braccatus), was last observed in 1987.

The finding that did surprise Kittelberger’s team was the correlation of wing shape to extinction. They found that bird species with a larger hand-wing index, that is more pointed wings, were more likely to have vanished earlier. Since pointier wings indicate stronger flying and dispersal abilities, the team predicted such birds would be better equipped to respond to environmental pressures than those with rounder wings.

Yet birds with rounder wings, those with smaller hand-wing ratios, proved to be more resilient.

“It likely ties with the fact that a lot of these birds that went extinct were on islands. For these species or their ancestors to have arrived at these islands to begin with, they would’ve needed the ability to fly across large, open distances. So a lot of these birds on islands have, not necessarily longer, but more pointed wings,” Kittelberger said. “Think of a swift or a swallow or a bird like an albatross that flies over the ocean. They have really pointy wings that allow them to fly really well, whereas birds in dense tropical rainforests are not flying these large distances, so they have rounded wings because they’re just moving in their local habitat patches.”

Ecological specialists, as opposed to generalists, face great challenges when their specific ecological niche is altered, so they tend to be less able to respond and adapt to disturbances, like invasive species or disruption of a food source.

In other findings, the study concluded more than 87% were endemic to islands; nearly two-thirds inhabited forests; 45% ate primarily insects and other invertebrates; and 20% were completely or partially flightless. Finally, species with big bodies were overly represented on the extinct list.

“Heavier birds have been more likely to be targeted for hunting, with several well-known examples of birds being hunted to extinction in part for food, including the Dodo, Great Auk (Pinguinus impennis), and Spectacled Cormorant (Urile perspicillatus),” the study said. “Body mass has also been linked with a species’ inhabitance of islands, as island birds tend to be larger than mainland species.” Of the 43 species whose average body weight exceeded 500 grams, or 1.1 pounds, three-quarters were endemic to an island.

The decade of the 1890s saw the highest number on extinctions, with 21 recorded. The 1980s was another bad decade for bird loss with 20 species, including the Kauai O’o. This latter decade “is noteworthy since focused and targeted conservation efforts were already underway globally before and during this period,” the study said. “Though the rate of extinction declined in the subsequent decades, the number of globally threatened species has only increased.”

The study, “Correlates of avian extinction timing around the world since 1500 CE,” was published Nov. 7 in the journal Avian Research. The research team included Colby J. Tanner, Amy N. Buxton, Amira Prewett and Çağan Şekercioğlu. Support for this research came from the University of Utah’s Graduate Research Fellowship.

The number of bird extinctions by decade since 1500, representing 216 species that have disappeared or have likely disappeared over the past five centuries. IUCN Status rankings consist of EX (Extinct), EW (Extinct in the Wild), CR (PE) (Critically Endangered but Possibly Extinct), and CR (Critically Endangered).

A map of global bird loss since 1500, including species confirmed
extinct and those likely to have disappeared. 

The proportion of 216 bird species globally extinct or likely lost since 1500 that were endemic to a region, found solely on islands, and were either flightless or partially flightless, as well as the breakdown of species by primary habitat or diet.

Credit

Kyle Kittelberger, University of Utah

Credit

Kyle Kittelberger, University of Utah

Journal

Avian Research

DOI

10.1016/j.avrs.2024.100213 

Method of Research

Data/statistical analysis

Subject of Research

Not applicable

Article Title

Correlates of avian extinction timing around the world since 1500 CE

Article Publication Date

27-Nov-2024

 

Chemical replacement of TNT explosive more harmful to plants, study shows

University of York

The increased use of a chemical compound to replace TNT in explosive devices has a damaging and long lasting effect on plants, new research has shown.

In recent years, TNT has started to be replaced with DNAN, but until now very little was known about how this substance impacts the environment and how long it can remain in the soil.

Researchers at the University of York have been studying the environmental impact of the explosive, TNT, for more than a decade. They have shown that the chemical compound, which is used by the military around the world, remains in the roots of plants where it inhibits growth and development.

Now a new study, led by Professor Neil Bruce at the University of York’s Department of Biology and Director of the Centre for Novel Agricultural Products (CNAP), however, has shown that DNAN has similar effects to TNT, but accumulates throughout the plant and lingers for longer.

Professor Neil Bruce said: “Similarly to TNT, DNAN reacts with a key plant enzyme, generating reactive superoxide, which is highly damaging to cells.  Over the course of our research we have genetically engineered plants to successfully detoxify land contaminated with munitions.

“Unfortunately DNAN is a very different story to TNT, as it accumulates in the above ground parts of the plant. While plants can use natural processes to reduce the toxicity of TNT, our studies found that plants appear to have no natural way of fighting off the toxic effects of DNAN, meaning that it persists in the plant and is toxic at much lower concentrations.”

Researchers warn that as DNAN is present throughout the plant and not just the root system, as is the case with TNT, there is a greater risk of animals eating the infected plant, introducing the toxin into the food chain. 

In previous studies by the York team, genetically modified grass was grown on land contaminated with military explosives, which successfully degraded contaminants to non-detectable levels in their plant tissues, but as yet there is currently no such method to remove or reduce DNAN.

The US is estimated to have over 10 million hectares of military land contaminated with constituents of explosives and the US government estimates that remediation of unexploded ordinances on US military training ranges alone will cost $16-165 billion. 

Dr Liz Rylott, co-author of the study from the University of York’s Department of Biology, said: “Recent years have seen an escalation in military explosives due to global conflicts, and so we are potentially looking at vast scales of pollution, which means there is an urgent need, and interest in, developing sustainable plant-based remediation strategies.

“We also don’t know what the limits of DNAN toxicity are in humans, so our hope is that our latest research will highlight that more work is urgently needed to understand its effects.” 

This research, published in the journal Nature Plants, was funded by the Strategic Environmental Research and Development Program (SERDP) of the U.S. Department of Defense and was in collaboration with researchers at the U.S. Army Engineer Research and Development Center (ERDC), U.S. Army Corps of Engineers.

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Journal

Nature Plants

 

Improved catalyst turns harmful greenhouse gases into cleaner fuels, chemical feedstocks

DOE/Oak Ridge National Laboratory

 

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With an improved catalyst, ORNL chemists converted two greenhouse gases, methane (CH4) and carbon dioxide (CO2), to syngas, a valuable mix of hydrogen (H2) and carbon monoxide (CO).

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Credit: Philip Gray/ORNL, U.S. Dept. of Energy

A chemical reaction can convert two polluting greenhouse gases into valuable building blocks for cleaner fuels and feedstocks, but the high temperature required for the reaction also deactivates the catalyst. A team led by the Department of Energy’s Oak Ridge National Laboratory has found a way to thwart deactivation. The strategy may apply broadly to other catalysts.

 

The team improved a reaction called dry reforming of methane that converts methane and carbon dioxide into syngas, a valued mixture of hydrogen and carbon monoxide used by oil and chemical companies worldwide. The team has applied for a patent for their invention as a way to minimize catalytic deactivation.

 

“Syngas is important because it's a platform for the production of a lot of chemicals of mass consumption,” said ORNL’s Felipe Polo-Garzon, who, with ORNL’s Junyan Zhang, led the study published in Nature Communications.

 

Improving the catalyst that speeds syngas production could have enormous impact on global energy security, cleaner fuels and chemical feedstocks. In countries lacking oil reserves, syngas derived from coal or natural gas is critical for making diesel and gasoline fuels. Moreover, syngas components can be used to make other commodity chemicals. Hydrogen, for example, can be used as a clean fuel or as a feedstock for ammonia to create fertilizer. Methanol, an alcohol that can be made from syngas, is a source of ingredients for producing plastics, synthetic fabrics and pharmaceuticals. Methanol is also a good carrier of hydrogen, which is hard to pressurize and dangerous to transport. As the simplest alcohol, methanol contains the highest ratio of hydrogen to carbon; it can be safely transported and converted to hydrogen at the destination.

 

“This [dry reforming of methane] reaction sounds attractive because you are converting two greenhouse gases into a valuable mixture,” Polo-Garzon said. “However, the issue for decades has been that the catalysts required to carry out this reaction deactivate quickly under reaction conditions, making this reaction nonviable on an industrial scale.”

 

To attain significant conversion of reactants, the reaction must be conducted at temperatures greater than 650 degrees Celsius, or 1,200 degrees Fahrenheit. “At this high temperature, the catalysts undergo two deactivation processes,” Polo-Garzon said. “One is sintering, in which you lose surface sites that undertake the reaction. The other is the formation of coke — basically solid carbon that blocks the catalyst from contacting the reactants.”

 

Catalysts work by providing a large surface area for reactions. Metal atoms such as nickel have electronic properties that allow them to temporarily bind reactants, making chemical bonds easier to break and create. Sintering causes nickel particles to clump, reducing the surface area available for chemical reactions.

 

Likewise, coking chokes a catalyst. “During the reaction on the catalyst surface, methane will lose its hydrogen atoms one by one until only its one carbon atom is left,” Zhang said. “If no oxygen bonds to it, leftover carbon will aggregate on the catalyst’s nickel surface, covering its active face. This coking deposition causes deactivation. It is extremely common in thermal catalysis for hydrocarbon conversion.”

 

Today, most commercial syngas is made by steam reforming of methane, a process that requires large amounts of water and heat and that also produces carbon dioxide. By contrast, dry reforming of methane requires no water and actually consumes carbon dioxide and methane.

 

By tuning interactions between the metal active sites and the support during catalyst synthesis, the scientists suppressed coke formation and metal sintering. The new catalyst provides outstanding performance for dry reforming of methane with extremely slow deactivation.

 

The novel catalyst consists of a crystalline material called a zeolite that contains silicon, aluminum, oxygen and nickel. The zeolite’s supportive framework stabilizes the metal active sites.

 

“Zeolite is like sand in composition,” Zhang said. “But unlike sand, it has a sponge-like structure filled with tiny pores, each around 0.6 nanometers in diameter. If you could completely open a zeolite to expose the surface area, 1 gram of sample would contain an area around 500 square meters, which is a tremendous amount of exposed surface.”

 

To synthesize the zeolite catalyst, the researchers remove some atoms of aluminum and replace them with nickel. “We're effectively creating a strong bond between the nickel and the zeolite host,” Polo-Garzon said. “This strong bond makes our catalyst resistant to degradation at high temperatures.”

 

The high-performance catalyst was synthesized at ORNL’s Center for Nanophase Materials Sciences. Zili Wu, leader of ORNL’s Surface Chemistry and Catalysis group, served as a strategy advisor for the project.

 

Zhang performed infrared spectroscopy, revealing that nickel was typically isolated and bound by two silicon atoms in the zeolite framework.

 

At DOE’s Brookhaven National Laboratory and SLAC National Accelerator Laboratory, ORNL’s Yuanyuan Li led X-ray absorption spectroscopy studies detailing the electronic and bonding structures of nickel in the catalyst. At ORNL, Polo-Garzon and Zhang used a technique called steady-state isotopic transient kinetic analysis to measure catalyst efficiency — the number of times a single active site converts a reactant into a product.

 

X-ray diffraction and scanning transmission electron microscopy characterized the structure and composition of materials at the nanoscale.

 

“In the synthesis method, we found that the reason the method works is because we're able to get rid of water, which is a byproduct of the catalyst synthesis,” Polo-Garzon said. “We asked colleagues to use density functional theory to look into why water matters when it comes to the stability of nickel.”

 

At Vanderbilt University, Haohong Song and De-en Jiang performed computational calculations showing that removing water from the zeolite strengthens its interactions with nickel.

 

Next, the researchers will develop other catalyst formulations for the dry reforming of methane reaction that are stable under a broad range of conditions. “We're looking for alternative ways to excite the reactant molecules to break thermodynamic constraints,” Polo-Garzon said.

 

“We relied on rational design, not trial and error, to make the catalyst better,” Polo-Garzon added. “We're not just developing one catalyst. We are developing design principles to stabilize catalysts for a broad range of industrial processes. It requires a fundamental understanding of the implications of synthesis protocols. For industry, that's important because rather than presenting a dead-end road in which you try something, see how it performs, and then decide where to go from there, we're providing an avenue to move forward.”

 

The DOE Office of Science funded the research. The work relied on several DOE Office of Science user facilities: the CNMS at ORNL; the Center for Functional Nanomaterials and the National Synchrotron Light Source II, both at Brookhaven; the Stanford Synchrotron Radiation Lightsource at SLAC and the National Energy Research Scientific Computing Center at Lawrence Berkeley National Laboratory.

 

UT-Battelle manages ORNL for DOE’s Office of Science. The single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science. — Dawn Levy

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Journal

Nature Communications

DOI

10.1038/s41467-024-50729-8 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Tuning metal-support interactions in nickel–zeolite catalysts leads to enhanced stability during dry reforming of methane