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  • richardmitnick 10:40 am on July 30, 2015 Permalink | Reply
    Tags: , Catalyst technology, , ,   

    From MIT: “How to look for a few good catalysts” 


    MIT News

    July 30, 2015
    David L. Chandler

    New research shows non-wetting surfaces promote chemical reaction rates.

    1
    Materials that have good wetting properties, as illustrated on the left, where droplets spread out flat, tend to have hydroxyl groups attached to the surface, which inhibits catalytic activity. Materials that repel water, as shown at right, where droplets form sharp, steep boundaries, are more conducive to catalytic activity, as shown by the reactions among small orange molecules. Illustration: Xiao Renshaw Wang

    Two key physical phenomena take place at the surfaces of materials: catalysis and wetting. A catalyst enhances the rate of chemical reactions; wetting refers to how liquids spread across a surface.

    Now researchers at MIT and other institutions have found that these two processes, which had been considered unrelated, are in fact closely linked. The discovery could make it easier to find new catalysts for particular applications, among other potential benefits.

    “What’s really exciting is that we’ve been able to connect atomic-level interactions of water and oxides on the surface to macroscopic measurements of wetting, whether a surface is hydrophobic or hydrophilic, and connect that directly with catalytic properties,” says Yang Shao-Horn, the W.M. Keck Professor of Energy at MIT and a senior author of a paper describing the findings in the Journal of Physical Chemistry C. The research focused on a class of oxides called perovskites that are of interest for applications such as gas sensing, water purification, batteries, and fuel cells.

    Since determining a surface’s wettability is “trivially easy,” says senior author Kripa Varanasi, an associate professor of mechanical engineering, that determination can now be used to predict a material’s suitability as a catalyst. Since researchers tend to specialize in either wettability or catalysis, this produces a framework for researchers in both fields to work together to advance understanding, says Varanasi, whose research focuses primarily on wettability; Shao-Horn is an expert on catalytic reactions.

    “We show how wetting and catalysis, which are both surface phenomena, are related,” Varanasi says, “and how electronic structure forms a link between both.”

    While both effects are important in a variety of industrial processes and have been the subject of much empirical research, “at the molecular level, we understand very little about what’s happening at the interface,” Shao-Horn says. “This is a step forward, providing a molecular-level understanding.”

    “It’s primarily an experimental technique” that made the new understanding possible, explains Kelsey Stoerzinger, an MIT graduate student and the paper’s lead author. While most attempts to study such surface science use instruments requiring a vacuum, this team used a device that could study the reactions in humid air, at room temperature, and with varying degrees of water vapor present. Experiments using this system, called ambient pressure X-ray photoelectron spectroscopy, revealed that the reactivity with water is key to the whole process, she says.

    The water molecules break apart to form hydroxyl groups — an atom of oxygen bound to an atom of hydrogen — bonded to the material’s surface. These reactive compounds, in turn, are responsible for increasing the wetting properties of the surface, while simultaneously inhibiting its ability to catalyze chemical reactions. Therefore, for applications requiring high catalytic activity, the team found, a key requirement is that the surface be hydrophobic, or non-wetting.

    “Ideally, this understanding helps us design new catalysts,” Stoerzinger says. If a given material “has a lower affinity for water, it has a higher affinity for catalytic activity.”

    Shao-Horn notes that this is an initial finding, and that “extension of these trends to broader classes of materials and ranges of hydroxyl affinity requires further investigation.” The team has already begun further exploration of these areas. This research, she says, “opens up the space of materials and surfaces we might think about” for both catalysis and wetting.

    The research team also included graduate student Wesley Hong, visiting scientist Livia Giordano, and postdocs Yueh-Lin Lee and Gisele Azimi at MIT; Ethan Crumlin and Hendrik Bluhm at Lawrence Berkeley National Laboratory; and Michael Biegalski at Oak Ridge National Laboratory. The work was supported by the National Science Foundation and the U.S. Department of Energy.

    See the full article here.

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  • richardmitnick 8:49 am on April 2, 2015 Permalink | Reply
    Tags: , Catalyst technology, ,   

    From SLAC: “Scientists Track Ultrafast Creation of a Catalyst with X-ray Laser” 


    SLAC Lab

    April 1, 2015

    Chemical Transformations Driven by Light Provide Key Insight to Steps in Solar-energy Conversion

    1
    This artistic rendering shows an iron-centered molecule that is severed by laser light (upper left). Within hundreds of femtoseconds, or quadrillionths of a second, a molecule of ethanol from a solvent rushes in (bottom right) to bond with the iron-centered molecule. (SLAC National Accelerator Laboratory)

    An international team has for the first time precisely tracked the surprisingly rapid process by which light rearranges the outermost electrons of a metal compound and turns it into an active catalyst – a substance that promotes chemical reactions.

    The results, published April 1 in Nature, could help in the effort to develop novel catalysts to efficiently produce fuel using sunlight. The research was performed with an X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory.

    “We were able to determine how light rearranges the outermost electrons of the compound on timescales down to a few hundred femtoseconds, or quadrillionths of a second,” said Philippe Wernet, a scientist at Helmholtz-Zentrum Berlin for Materials and Energy who led the experiment.

    Researchers hope that learning these details will allow them to develop rules for predicting and controlling the short-lived early steps in important reactions, including the ones plants use to turn sunlight and water into fuel during photosynthesis. Scientists are seeking to replicate these natural processes to produce hydrogen fuel from sunlight and water, for example, and to master the chemistry required to produce other renewable fuels.

    “The eventual goal is to design chemical reactions that behave exactly the way you want them to,” Wernet said.

    In the experiment at SLAC’s Linac Coherent Light Source, a DOE Office of Science User Facility, the scientists studied a yellowish fluid called iron pentacarbonyl, which consists of carbon monoxide “spurs” surrounding a central iron atom. It is a basic building block for more complex compounds and also provides a simple model for studying light-induced chemical reactions.

    SLAC LCLS Inside
    LCLS

    Researchers had known that exposing this iron compound to light can cleave off one of the five carbon monoxide spurs, causing the molecule’s remaining electrons to rearrange. The arrangement of the outermost electrons determines the molecule’s reactivity – including whether it might make a good catalyst – and also informs how reactions unfold.

    What wasn’t well understood was just how quickly this light-triggered transformation occurs and which short-lived intermediate states the molecule goes through on its way to becoming a stable product.

    At LCLS, the scientists struck a thin stream of the iron compound, which was mixed into an ethanol solvent, with pulses of optical laser light to break up the iron-centered molecules. Just hundreds of femtoseconds later, an ultrabright X-ray pulse probed the molecules’ transformation, which was recorded with sensitive detectors.

    By varying the arrival time of the X-ray pulses, they tracked the rearrangements of the outermost electrons during the molecular transformations.

    Roughly half of the severed molecules enter a chemically reactive state in which their outermost electrons are prone to binding other molecules. As a consequence, they either reconnect with the severed part or bond with an ethanol molecule to form a new compound. In other cases the outermost electrons in the molecule stabilize themselves in a configuration that makes the molecule non-reactive. All of these changes were observed within the time it takes light to travel a few thousandths of an inch.

    “To see this happen so quickly was extremely surprising,” Wernet said.

    Several years’ worth of data analysis and theoretical work were integral to the study, he said. The next step is to move on from model compounds to LCLS studies of the actual molecules used to make solar fuels.

    “This was a really exciting experiment, as it was the first time we used the LCLS to study chemistry in a liquid compound,” said Josh Turner, a SLAC staff scientist who participated in the experiment. “The LCLS is unique in the world in its ability to resolve these types of ultrafast processes in the right energy range for this compound.”

    SLAC’s Kelly Gaffney, a chemist who contributed expertise in how the changing arrangement of electrons steered the chemical reactions, said, “This work helps set the stage for future studies at LCLS and shows how cooperation across different research areas at SLAC enables broader and better science.”

    In addition to researchers from Helmholtz-Zentrum Berlin for Materials and Energy and LCLS, other scientists who assisted in the study were from: SLAC’s Stanford Synchrotron Radiation Lightsource; the SLAC and Stanford PULSE Institute; University of Potsdam, Max Planck Institute for Biophysical Chemistry, Goettingen University and DESY lab in Germany; Stockholm University and MAX-lab in in Sweden; Utrecht University in the Netherlands; Paul Scherrer Institute in Switzerland; and the University of Pennsylvania.

    This work was supported by the Volkswagen Foundation, the Swedish Research Council, the Carl Tryggers Foundation, the Magnus Bergvall Foundation, Collaborative Research Centers of the German Science Foundation and the Helmholtz Virtual Institute “Dynamic Pathways in Multidimensional Landscapes,” and the U.S. Department of Energy Office of Science.

    See the full article here.

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 6:53 am on January 20, 2015 Permalink | Reply
    Tags: , Catalyst technology,   

    From Stanford: “Stanford engineers use brilliant X-rays to illuminate catalysis, revise theories” 

    Stanford University Name
    Stanford University

    January 19, 2015
    Andrew Myers

    Many of today’s most promising renewable energy technologies – fuel cells, water splitters and artificial photosynthesis – rely upon catalysts to expedite the chemical reactions at the heart of their potential. Catalysts are materials that enhance chemical reactions without being consumed in the process. For over a century, engineers across the world have engaged in a near-continual search for ways to improve catalysts for their devices and processes.

    Against this backdrop, a team of researchers at Stanford has used high-brilliance X-rays in a new way to peer into active reactions using metal oxides as the catalyst. Ceramic-like metal oxides, such as iron oxide, a material similar to rust, are desirable as catalysts because they are more abundant and more stable than typical catalysts made of rare metals like platinum, ruthenium and rhodium.

    1
    Lead author Dr. David Mueller using brilliant X-rays to characterize working fuel cells at the Advanced Light Source at the Lawrence Berkeley National Laboratory. He is a staff scientist at the Juelich, Germany, research center.

    Although they may be more abundant, metal oxides are also less scientifically understood than their metallic counterparts.

    The Stanford engineers were able to use enhanced X-ray technology in a novel way to observe the behavior of individual electrons during these important chemical processes. What they learned has upended long-held scientific understanding of how metal oxide catalysts work.

    “A freshman chemistry student would tell you, by intuition, that in a material made up of iron and oxygen – as iron oxide is – it is the iron, the metal ion, that is the catalytically active component. We discovered exactly the opposite. Oxygen ions are the ones gaining and losing electrons most actively. Iron is almost completely inactive,” explained William Chueh, an assistant professor of materials science and engineering and senior author of the study published in the journal Nature Communications.

    The results are a 180-degree shift from what went before, assert Chueh and colleagues – postdoctoral scholar David N. Mueller and graduate student Michael L. Machala, both of whom work in Chueh’s lab, and Hendrik Bluhm, a staff scientist at Lawrence Berkeley National Laboratory. The findings could reshape the search for new and better catalysts.

    “We’ve been looking in the wrong place. We thought oxygen was the spectator, but it’s the protagonist, and we can now look to develop new catalysts by modifying the oxygen ions in these systems,” Chueh said.

    Redox redux

    In reality, the catalyst is consumed and then recreated during the reaction, but the net result is the same: zero effect on the catalyst, but profound implications for humanity.

    Catalysts play a fundamental role in our lives, though few outside the community of researchers and engineers who study them know much about how they work. Metal oxides, in particular, are leading candidates for use as catalysts at the heart of a basic chemical reaction known as reduction-oxidation, or “redox” for short. Redox reactions are key to renewable energy uses.

    One of the best examples is water splitting. Electricity generated from the sun via solar panels is passed through water. The electric current separates (“splits”) the water into its two constituent elements: environmentally beneficial oxygen and clean-burning hydrogen. The hydrogen can then be stored and later burned as fuel to generate electricity when the sun is not shining.
    A fundamental search

    One of the major hurdles on the path to these renewable energy applications has been the catalyst. The Chueh team’s research represents one of the first times science has used high-brilliance X-rays to look so closely at these reactions. The experiments were performed at the Advanced Light Source at the Lawrence Berkeley National Laboratory. Until recently the reactions under such surveillance had to be done in a vacuum, but no longer.

    “It simply wasn’t possible to study how gas molecules, particularly oxygen, interacted with the catalyst because we couldn’t include them in the experiments. Thanks to these new techniques, we can study oxygen in the reactions,” Chueh said.

    The advance allowed the researchers to observe and follow the electrons as they do their work and to better understand how they behave during the reactions. What they have learned is “extremely critical” to fundamental-level understanding of catalysts and could lead in exciting new directions in catalyst design, Chueh added. Research like this provides a glimpse of a future in which metal oxides will become more competitive with traditional catalysts.

    “We’re working at the most basic levels of science to understand what makes a material tick, and what limits its performance and why. This is fundamental work, but it is inspiring, as well,” Chueh said, adding: “It will help us design better technologies from the atomic level up, to someday have great commercial impact.”

    Media Contact

    Tom Abate, Stanford Engineering: tabate@stanford.edu, (650) 735-2245
    Dan Stober, Stanford News Service: (650) 721-6965, dstober@stanford.edu

    See the full article here.

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 6:11 pm on August 8, 2014 Permalink | Reply
    Tags: , Catalyst technology,   

    From EMSL: “Improving catalysts” 

    EMSL
    Environmental Molecular Sciences Laboratory (EMSL)

    No Date
    No Writer Credit

    Better bimetallic catalysts for fuel and chemical industries

    The Science

    Nanocatalysts consisting of two metals can offer superior performance compared with those made up of only one metal, so they are widely used for industrial processes that generate fuels and chemicals from natural gas, coal or plant biomass. However, complex interactions between the two metals during catalytic reactions can lower catalytic efficiency. This study addresses this issue by directly observing the changes of platinum-cobalt nanoparticles in operating conditions. Such particles are used as catalysts to convert carbon dioxide and hydrogen into long-chain carbon fuels and are important to the operation of low-temperature fuel cells.

    cat
    No image credit

    The Impact

    The new insights on the transformations of multiple component catalysts will allow researchers to optimally design similar catalysts to improve their performance, extend their lifetime, and reduce their environmental impact. Moreover, this research could guide efforts to minimize the use of precious metal components such as platinum and therefore reduce the cost of catalysts and lead to a more economical product for consumers.

    Summary

    In a multi-national lab effort led by Haimei Zheng from Lawrence Berkeley National Laboratory, researchers from DOE’s Pacific Northwest National Laboratory and collaborators examined real-time changes in the atomic structure of nanoparticles consisting of platinum and cobalt during reactions with oxygen and hydrogen using environmental transmission electron microscopy (ETEM), a specialized instrument housed in the Quiet Wing at the Environmental Molecular Sciences Laboratory (EMSL), a DOE national scientific user facility. The work was supported by the Chemical Imaging Initiative at PNNL.

    During oxidation in an oxygen gas environment, cobalt migrated to the nanoparticle surface, where it formed a cobalt oxide film that covered the platinum. Within ten seconds, this oxide film broke apart to form distinct islands and created voids in the interior of the particle, which can impair catalyst performance. This process was reversed during reduction in a hydrogen gas environment, which caused the cobalt oxide patches to decrease and the cobalt to migrate back to the bulk of the particle. Reduction with hydrogen also caused a layer of platinum to form on the particle surface, which is expected to improve catalyst performance.

    These new insights into the atomic scale behavior of nanoparticles consisting of multiple metals in reactive environments pave the way for a deeper understanding of the properties of multi-component catalysts and will guide efforts to improve their performance. In particular, the findings can be used to design multi-component catalysts that do not form oxide islands on the nanoparticle surface, but rather retain the material with higher catalytic performance on the nanoparticle surface during catalytic reactions.

    Funding

    This research was supported by DOE’s Office of Science and the Office of Basic Energy Sciences’ Chemical Science Division, as well as the Chemical Imaging Initiative at PNNL through the

    Laboratory Directed Research and Development Programs at PNNL and LBNL.

    See the full article here.

    EMSL is a national scientific user facility that is funded and sponsored by DOE’s Office of Biological & Environmental Research. As a user facility, our scientific capabilities – people, instruments and facilities – are available for use by the global research community. We support BER’s mission to provide innovative solutions to the nation’s environmental and energy production challenges in areas such as atmospheric aerosols, feedstocks, global carbon cycling, biogeochemistry, subsurface science and energy materials.

    A deep understanding of molecular-level processes is critical to gaining a predictive, systems-level understanding of the impacts of aerosols and terrestrial systems on climate change; making clean, affordable, abundant energy; and cleaning up our legacy wastes. Visit our Science page to learn how EMSL leads in these areas, through our Science Themes.

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  • richardmitnick 9:13 am on August 1, 2014 Permalink | Reply
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    From Brookhaven Lab: “Nanostructured Metal-Oxide Catalyst Efficiently Converts CO2 to Methanol” 

    Brookhaven Lab

    July 31, 2014
    Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174printer iconPrint

    Highly reactive sites at interface of two nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products

    people
    Dario Stacchiola and Kumudu Mudiyanselage make notes in the data log while Fang Xu (seated) and Jose Rodriguez view microscopic images of the catalyst and Ping Liu and Sanjaya Senanayake adjust the ambient-pressure scanning tunneling microscope. No image credit

    Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have discovered a new catalytic system for converting carbon dioxide (CO2) to methanol—a key commodity used to create a wide range of industrial chemicals and fuels. With significantly higher activity than other catalysts now in use, the new system could make it easier to get normally unreactive CO2 to participate in these reactions.

    “Developing an effective catalyst for synthesizing methanol from CO2 could greatly expand the use of this abundant gas as an economical feedstock,” said Brookhaven chemist Jose Rodriguez, who led the research. It’s even possible to imagine a future in which such catalysts help mitigate the accumulation of this greenhouse gas, by capturing CO2 emitted from methanol-powered combustion engines and fuel cells, and recycling it to synthesize new fuel.

    That future, of course, will be determined by a variety of factors, including economics. “Our basic research studies are focused on the science—the discovery of how such catalysts work, and the use of this knowledge to improve their activity and selectivity,” Rodriguez emphasized.

    The research team, which included scientists from Brookhaven, the University of Seville in Spain, and Central University of Venezuela, describes their results in the August 1, 2014, issue of the journal Science.

    New tools for discovery

    fu
    Fang Xu, a Stony Brook University PhD student working with the Brookhaven Lab team on studies to identify more effective catalysts for industrial processes, peers into the ambient-pressure scanning tunneling microscope used in these experiments.

    Because CO2 is normally such a reluctant participant in chemical reactions, interacting weakly with most catalysts, it’s also rather difficult to study. These studies required the use of newly developed in-situ (or on-site, meaning under reaction conditions) imaging and chemical “fingerprinting” techniques. These techniques allowed the scientists to peer into the dynamic evolution of a variety of catalysts as they operated in real time. The scientists also used computational modeling at the University of Seville and the Barcelona Supercomputing Center to provide a molecular description of the methanol synthesis mechanism.

    The team was particularly interested in exploring a catalyst composed of copper and ceria (cerium-oxide) nanoparticles, sometimes also mixed with titania. The scientists’ previous studies with such metal-oxide nanoparticle catalysts have demonstrated their exceptional reactivity in a variety of reactions. In those studies, the interfaces of the two types of nanoparticles turned out to be critical to the reactivity of the catalysts, with highly reactive sites forming at regions where the two phases meet.

    To explore the reactivity of such dual particle catalytic systems in converting CO2 to methanol, the scientists used spectroscopic techniques to investigate the interaction of CO2 with plain copper, plain cerium-oxide, and cerium-oxide/copper surfaces at a range of reaction temperatures and pressures. Chemical fingerprinting was combined with computational modeling to reveal the most probable progression of intermediates as the reaction from CO2 to methanol proceeded.

    These studies revealed that the metal component of the catalysts alone could not carry out all the chemical steps necessary for the production of methanol. The most effective binding and activation of CO2 occurred at the interfaces between metal and oxide nanoparticles in the cerium-oxide/copper catalytic system.

    “The key active sites for the chemical transformations involved atoms from the metal [copper] and oxide [ceria or ceria/titania] phases,” said Jesus Graciani, a chemist from the University of Seville and first author on the paper. The resulting catalyst converts CO2 to methanol more than a thousand times faster than plain copper particles, and almost 90 times faster than a common copper/zinc-oxide catalyst currently in industrial use.

    two
    Scanning tunneling microscope image of a cerium-oxide and copper catalyst (CeOx-Cu) used in the transformation of carbon dioxide (CO2) and hydrogen (H2) gases to methanol (CH3OH) and water (H2O). In the presence of hydrogen, the Ce4+ and Cu+1 are reduced to Ce3+ and Cu0 with a change in the structure of the catalyst surface.

    This study illustrates the substantial benefits that can be obtained by properly tuning the properties of a metal-oxide interface in catalysts for methanol synthesis.

    “It is a very interesting step, and appears to create a new strategy for the design of highly active catalysts for the synthesis of alcohols and related molecules,” said Brookhaven Lab Chemistry Department Chair Alex Harris.

    The work at Brookhaven Lab was supported by the DOE Office of Science. The studies performed at the University of Seville were funded by the Ministerio de Economía y Competitividad of Spain and the European Regional Development Fund. The Instituto de Tecnologia Venezolana para el Petroleo supported part of the work carried out at the Central University of Venezuela.

    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 science.energy.gov.

    See the full article, with video, here.

    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. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 8:46 am on June 6, 2014 Permalink | Reply
    Tags: , Catalyst technology, ,   

    From Brookhaven Lab: “Ionic Liquid Boosts Efficiency of CO2 Reduction Catalyst” 

    Brookhaven Lab

    June 6, 2014
    Karen McNulty Walsh

    Promising approach for converting abundant gas to building blocks for liquid fuels and other useful chemicals

    Wouldn’t it be nice to use solar- or wind-generated electricity to turn excess carbon dioxide—one of the gases trapping heat in Earth’s atmosphere—into fuels and other useful chemicals? The process would store up the intermittent solar or wind energy in a form that could be used when and where it was needed, including in transportation applications, all while getting rid of some greenhouse gas. The trick is to find the right catalysts to facilitate the conversion of CO2 with high activity and minimal energy input.

    two
    Yasuo Matsubara and David Grills

    One useful product of such CO2 reduction reactions is carbon monoxide (CO), a building block for making methanol and liquid hydrocarbons that could replace gasoline. So far, the catalysts tried for this reaction are often lacking in efficiency and/or specificity; either they take too much energy, are too slow, or make too wide a variety of products to be useful. Now a group of chemists at the U.S. Department of Energy’s Brookhaven National Laboratory reports a new approach: performing the electrochemical reaction in an ionic liquid, which acts as both the solvent and electrolyte.

    The process—described in a paper recently published in The Journal of Physical Chemistry Letters, published by the American Chemical Society (ACS)—was shown to boost both the energy efficiency and speed of the reaction for a well-known catalyst, with no loss of product selectivity, compared to the same reaction in a standard organic solvent solution. The paper was just selected as an ACS Editors’ Choice article. Only one such article is selected each day from the entire portfolio of ACS journals.

    Ionic liquids are salts made of positive and negative ions, similar to the sodium and chloride ions of table salt, but in liquid form at room temperature. Their blend of positive and negative charges makes them excellent conductors (electrolytes) and gives them unique properties, resulting in their recent emergence as superior alternatives to conventional organic solvents for many energy-related applications.

    Ionic liquids have previously shown some promise at improving the energy efficiency of the direct electrochemical reduction of CO2 at metal electrodes. The new work, led by Brookhaven Lab chemist David Grills and Yasuo Matsubara of the Japan Science and Technology Agency, is the first attempt to use ionic liquids to improve CO2 reduction using a homogeneous electrocatalyst—where both the reactants and catalyst are dissolved in a liquid. Homogeneous CO2 reduction catalysts are generally more selective in the products they produce.

    “Our experiment resulted in an improvement in both the energy efficiency and kinetics of the CO2 reduction process for the catalyst we studied, with no loss of product selectivity,” Grills said.

    The reason for the improvement, the scientists suspect, is a special interaction between one of the ionic liquid’s ions and an intermediate form of the catalyst that results in a lowering of the activation energy required for the reaction.

    The new approach will undoubtedly inspire a great deal of follow-up effort.

    “We expect that these initial results will open up new possibilities for studying ionic-liquid-enhanced CO2 reduction with a range of homogeneous catalysts and different types of ionic liquids,” said Matsubara.

    The work may even point the way to catalytic systems that can directly convert CO2 to other useful chemicals.

    Brookhaven’s role in this research was funded by the DOE Office of Science.

    See the full article here.

    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. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 11:55 am on April 23, 2014 Permalink | Reply
    Tags: , Catalyst technology, , ,   

    From PNNL Lab: “Halving hydrogen” 

    PNNL Lab

    April 23, 2014
    Mary Beckman

    – Like a hungry diner ripping open a dinner roll, a fuel cell catalyst that converts hydrogen into electricity must tear open a hydrogen molecule. Now researchers have captured a view of such a catalyst holding onto the two halves of its hydrogen feast. The view confirms previous hypotheses and provides insight into how to make the catalyst work better for alternative energy uses.

    cat
    Neutron crystallography shows this iron catalyst gripping two hydrogen atoms (red spheres). This arrangement allows an unusual dihydrogen bond to form between the hydrogen atoms (red dots).

    This study is the first time scientists have shown precisely where the hydrogen halves end up in the structure of a molecular catalyst that breaks down hydrogen, the team reported online April 22 in Angewandte Chemie International Edition. The design of this catalyst was inspired by the innards of a natural protein called a hydrogenase enzyme.
    “The catalyst shows us what likely happens in the natural hydrogenase system,” said Morris Bullock of the Department of Energy’s Pacific Northwest National Laboratory. “The catalyst is where the action is, but the natural enzyme has a huge protein surrounding the catalytic site. It would be hard to see what we have seen with our catalyst because of the complexity of the protein.”

    Ironing Out Expense

    Hydrogen-powered fuel cells offer an alternative to burning fossil fuels, which generates greenhouse gases. Molecular hydrogen — two hydrogen atoms linked by an energy-rich chemical bond — feeds a fuel cell. Generating electricity through chemical reactions, the fuel cell spits out water and power.

    If renewable power is used to store energy in molecular hydrogen, these fuel cells can be carbon-neutral. But fuel cells aren’t cheap enough for everyday use.
    To make fuel cells less expensive, researchers turned to natural hydrogenase enzymes for inspiration. These enzymes break hydrogen for energy in the same way a fuel cell would. But while conventional fuel cell catalysts require expensive platinum, natural enzymes use cheap iron or nickel at their core.
    Researchers have been designing catalysts inspired by hydrogenase cores and testing them. In this work, an important step in breaking a hydrogen molecule so the bond’s energy can be captured as electricity is to break the bond unevenly. Instead of producing two equal hydrogen atoms, this catalyst must produce a positively charged proton and a negatively charged hydride.

    The physical shape of a catalyst — along with electrochemical information — can reveal how it does that. So far, scientists have determined the overall structure of catalysts with cheap metals using X-ray crystallography, but hydrogen atoms can’t be located accurately using X-rays. Based on chemistry and X-ray methods, researchers have a best guess for the position of hydrogen atoms, but imagination is no substitute for reality.

    Bullock, Tianbiao “Leo” Liu and their colleagues at the Center for Molecular Electrocatalysis at PNNL, one of DOE’s Energy Frontier Research Centers, collaborated with scientists at the Spallation Neutron Source at Oak Ridge National Laboratory in Tennessee to find the lurking proton and hydride. Using a beam of neutrons like a flashlight allows researchers to pinpoint the nucleus of atoms that form the backbone architecture of their iron-based catalyst.

    Bonding Jamboree

    To use their iron-based catalyst in neutron crystallography, the team had to modify it chemically so it would react with the hydrogen molecule in just the right way. Neutron crystallography also requires larger crystals as starting material compared to X-ray crystallography.

    “We were designing a molecule that represented an intermediate in the chemical reaction, and it required special experimental techniques,” Liu said. “It took more than six months to find the right conditions to grow large single crystals suitable for neutron diffraction. And another six months to pinpoint the position of the split H2 molecule.”

    Crystallizing their catalyst of interest into a nugget almost 40 times the size needed for X-rays, the team succeeded in determining the structure of the iron-based catalyst.
    The structure, they found, confirmed theories based on chemical analyses. For example, the barbell-shaped hydrogen molecule snuggles into the catalyst core. On being split, the negatively charged hydride attaches to the iron at the center of the catalyst; meanwhile, the positively charged proton attaches to a nitrogen atom across the catalytic core. The researchers expected this set-up, but no one had accurately characterized it in an actual structure before.

    In this form, the hydride and proton form a type of bond uncommonly seen by scientists — a dihydrogen bond. The energy-rich chemical bond between two hydrogen atoms in a molecule is called a covalent bond and is very strong. Another bond called a “hydrogen bond” is a weak one formed between a slightly positive hydrogen and another, slightly negative atom.
    Hydrogen bonds stabilize the structure of molecules by tacking down chains as they fold over within a molecule or between two independent molecules. Hydrogen bonds are also key to water surface tension, ice’s ability to float and even a snowflake’s shape.

    The dihydrogen bond seen in the structure is much stronger than a single hydrogen bond. Measuring the distance between atoms reveals how tight the bond is. The team found that the dihydrogen bond was much shorter than typical hydrogen bonds but longer than typical covalent bonds. In fact, the dihydrogen bond is the shortest of its type so far identified, the researchers report.

    This unusually strong dihydrogen bond likely plays into how well the catalyst balances tearing the hydrogen molecule apart and putting it back together. This balance allows the catalyst to work efficiently.

    “We’re not too far from acceptable with its efficiency,” said Bullock. “Now we just want to make it a little more efficient and faster.”

    This work was supported by the Department of Energy Office of Science.

    See the full article here.

    Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

    PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

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  • richardmitnick 7:38 pm on March 3, 2014 Permalink | Reply
    Tags: , Catalyst technology, ,   

    From SLAC: “Scientists Say New Catalyst Could Lead to Clean, Low-Cost Methanol Production” 

    Created by scientists from Stanford, SLAC and Denmark, the new nickel-gallium catalyst converts carbon dioxide emissions into an important industrial chemical and potential fuel

    March 3, 2014
    Mark Shwartz, Precourt Institute for Energy, Stanford University

    An international research team has discovered a potentially clean, low-cost way to convert carbon dioxide into methanol, a key ingredient in the production of plastics, adhesives and solvents, and a promising fuel for transportation.

    Scientists from Stanford University, SLAC National Accelerator Laboratory and the Technical University of Denmark combined theory and experimentation to identify a new nickel-gallium catalyst that converts hydrogen and carbon dioxide into methanol with fewer side-products than the conventional catalyst. The results are published in the March 2 online edition of the journal Nature Chemistry.

    “Methanol is processed in huge factories at very high pressures using hydrogen, carbon dioxide and carbon monoxide from natural gas,” said study lead author Felix Studt, a staff scientist at SLAC. “We are looking for materials than can make methanol from clean sources, such as sunshine, under low-pressure conditions, while generating low amounts of carbon monoxide.”

    The ultimate goal is to develop a large-scale manufacturing process that is nonpolluting and carbon neutral using clean hydrogen, the authors said.

    “Imagine if you could synthesize methanol using hydrogen from renewable sources, such as water split by sunlight, and carbon dioxide captured from power plants and other industrial smokestacks,” said co-author Jens Nørskov, a professor of chemical engineering at Stanford. “Eventually we would also like to make higher alcohols, such as ethanol and propanol, which, unlike methanol, can be directly added to gasoline today.”
    Industrial methanol

    Worldwide, about 65 million metric tons of methanol are produced each year for use in the manufacture of paints, polymers, glues and biofuels. In a typical methanol plant, natural gas and water are converted to synthesis gas (syngas), which consists of carbon monoxide, carbon dioxide and hydrogen. The syngas is then converted into methanol in a high-pressure process using a catalyst made of copper, zinc and aluminum.

    “We spent a lot of time studying methanol synthesis and the industrial process,” Studt said. “It took us about three years to figure out how the process works and to identify the active sites on the copper-zinc-aluminum catalyst that synthesize methanol.”

    Once he and his colleagues understood methanol synthesis at the molecular level, they began the hunt for a new catalyst capable of synthesizing methanol at low pressures using only hydrogen and carbon dioxide. Instead of testing a variety of compounds in the lab, Studt searched for promising catalysts in a massive computerized database that he and co-author Frank Abild-Pedersen developed at SLAC.

    “The technique is known as computational materials design,” explained Nørskov, the director of the SUNCAT Center for Interface Science and Catalysis at Stanford and SLAC. “You get ideas for new functional materials based entirely on computer calculations. There is no trial-and-error in the lab first. You use your insight and enormous computer power to identify new and interesting materials, which can then be tested experimentally.”

    image
    Artist’s rendering of the nickel-gallium active site, which synthesizes hydrogen and carbon dioxide into methanol. Nickel atoms are light grey, gallium atoms are dark grey, and oxygen atoms are red. (Jens Hummelshoj/SLAC)

    Studt compared the copper-zinc-aluminum catalyst with thousands of other materials in the database. The most promising candidate turned out to be a little-known compound called nickel-gallium.

    “Once we got the name of the compound out of the computer, someone still had to test it,” Nørskov said. “So we had to have a good experimental partner.”

    Nørskov turned to a research group at the Technical University of Denmark led by Ib Chorkendorff, a co-author of the research paper. First, the Danish team carried out the task of synthesizing nickel and gallium into a solid catalyst. Then the scientists conducted a series of experiments to see if the new catalyst could actually produce methanol at ordinary room pressure.

    The lab tests confirmed that the computer had made the right choice. At high temperatures, nickel-gallium produced more methanol than the conventional copper-zinc-aluminum catalyst, and considerably less of the carbon monoxide byproduct.

    “You want to make methanol, not carbon monoxide,” Chorkendorff said. “You also want a catalyst that’s stable and doesn’t decompose. The lab tests showed that nickel-gallium is, in fact, a very stable solid.”

    While these results show promise, a great deal of work lies ahead. “We’d like to make the catalyst a little more clean,” Chorkendorff added. “If it contains just a few nanoparticles of pure nickel, the output drops quite a bit, because pure nickel is lousy at synthesizing methanol. In fact, it makes all sorts of chemical byproducts that you don’t want.”

    Nickel is relatively abundant, and gallium, although more expensive, is widely used in the electronics industry. This suggests that the new catalyst could eventually be scaled up for industrial use, according to the authors. But to make methanol synthesis a truly carbon-neutral process will require overcoming many additional hurdles, they noted.

    Other co-authors of the study are Jens Hummelshøj of SLAC; and Irek Sharafutdinov, Christian Elkjaer and Søren Dahl of the Technical University of Denmark.

    The research was supported by the U.S. Department of Energy, the Danish National Research Foundation and the Danish Ministry of Science, Technology and Innovation.

    See the full article here.

    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 4:07 pm on August 13, 2013 Permalink | Reply
    Tags: , Catalyst technology,   

    From PNNL Lab: “New Catalyst Dives into Water to Produce Hydrogen” 

    August 2013
    Suraiya Farukhi
    Web Publishing

    Earth-abundant metal at heart of material that creates 170,000 molecules a second

    Results:Few catalysts are energy efficient, highly active, stable, and operate in water, but a nickel-based catalyst designed at the Center for Molecular Electrocatalysis at Pacific Northwest National Laboratory quickly produces hydrogen molecules in solutions with 75 percent water. This catalyst contains tailored relays that allow the catalyst to quickly shuttle protons from the solution to the heart of the catalyst, where they are added to electrons. The catalyst is known to be energy efficient, stable and highly active. With the modified design, it now operates in water, producing up to 170,000 hydrogen molecules per second. The study on this catalyst was highlighted as a hot article in Chemical Communications.

    ‘We’ve moved from pure organic solvents to solutions with increasing amounts of water,’ said Dr. Monte Helm, Deputy Director of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center. ‘We found that our catalyst performed better with water than in an organic solvent alone.’

    warerbug
    Few catalysts are energy efficient, highly active, stable, and able to operate in water; however, a redesigned nickel-based catalyst quickly and efficiently turns protons and electrons into hydrogen. One day, power generated by solar farms and wind turbines could be used to drive this transformation. This catalyst works in solutions with 75 percent water. John Darmon at PNNL captured this research in an image that was selected for the journal’s cover.
    We report a synthetic nickel complex containing proton relays that catalyzes the production of hydrogen in aqueous acetonitrile with turnover frequencies of 750-170,000/s at experimentally determined overpotentials of 310-470 mV.

    Why It Matters: Solar power is not a large part of our nation’s energy grid, in part because of its intermittent nature and the challenges involved in storing the energy. One option is to combine the electrons generated with protons and create molecular hydrogen. The hydrogen stores the energy for later use. Catalysts are needed to drive this reaction, and this study answers a fundamental question about these catalysts by showing how to design proton relays that achieve fast, energy-efficient materials able to work in water.

    ‘We are getting closer to what we need for a real-world catalyst,’ said Dr. Morris Bullock, Director of the Center for Molecular Electrocatalysis.”

    See the full article here.

    Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

    PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

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  • richardmitnick 8:52 pm on July 18, 2013 Permalink | Reply
    Tags: , Catalyst technology,   

    From Brookhaven Lab: “Researchers Help Show New Way to Study and Improve Catalytic Reactions” 

    Brookhaven Lab

    July 18, 2013
    Contacts: Justin Eure, (631) 344-2347 or Peter Genzer, (631) 344-3174

    [The following press release on advancing nanocatalyst structure and performance was issued by the University of Pennsylvania. Scientists Rosa Diaz and Eric Stach of Brookhaven National Laboratory’s Center for Functional Nanomaterials (CFN) combined results from two electron microscopes to reveal crucial information on the size and configuration of the catalysts. The collaboration correlated the CFN structural analysis with reactivity tests to determine the active sites of the catalysts…

    University of Pennsylvania Media contact: Evan Lerner at elerner@upenn.edu or 215-573-6604]

    University of Pennsylvania leads collaboration to test catalyst structures and enhance nanotechnology performance and fabrication.

    Catalysts are everywhere. They make chemical reactions that normally occur at extremely high temperatures and pressures possible within factories, cars and the comparatively balmy conditions within the human body. Developing better catalysts, however, is mainly a hit-or-miss process.

    Now, a study by researchers at the University of Pennsylvania, the University of Trieste and Brookhaven National Laboratory has shown a way to precisely design the active elements of a certain class of catalysts, showing which parameters are most critical for improving performance.

    This highly controlled process could be a new paradigm for fine-tuning catalysts used in everything from making new materials to environmental remediation.

    study
    By precisely designing a series of nanocrystals with different sizes, shapes and compositions, researchers showed that the efficiency of certain catalysts depends on the interface between their two materials. (Image: Matteo Cargnello)

    The research is the result of a highly collaborative effort between the three institutions. It was led by Christopher Murray, a Penn Integrates Knowledge Professor with appointments in the Department of Chemistry in the School of Arts and Sciences and the Department of Materials Science and Engineering in the School of Engineering and Applied Science, and Matteo Cargnello, a postdoctoral fellow in Murray’s group. Cargnello was a graduate student in Paolo Fornasiero’s group at the University of Trieste when the research began and also worked with Raymond Gorte, professor in the Department of Chemical and Biomolecular Engineering, after coming to Penn. Penn graduate students Vicky Doan-Nguyen and Thomas R. Gordon, as well as Brookhaven’s Rosa Diaz and Eric Stach, also contributed to the study. It was published in the journal Science.

    Murray’s team set out to improve the process for designing a class of reaction-promoting materials known as supported catalysts. These catalysts are made of two different solid substances—one supporting the other—but existing techniques for fabricating them don’t provide much in the way of precisely controlling their parameters. Because of the lack of uniformity in conventional catalysts, it can be difficult to tell which aspects of their combination lead to better systems.

    ‘In putting together materials design, functional testing and state-of-the art-characterization tools, we’re looking to develop a feedback loop,’ Murray said. ‘Improving our understanding about the active components of these catalysts can tell us what to emphasize in future systems.'”

    See the full article here.

    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. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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