MSGID: 1:317/3 642f9c69   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    New atomic-scale understanding of catalysis could unlock massive energy   
   savings    
      
     Date:   
         April 6, 2023   
     Source:   
         University of Wisconsin-Madison   
     Summary:   
         In an advance they consider a breakthrough in computational   
         chemistry research, chemical engineers have developed model of how   
         catalytic reactions work at the atomic scale. This understanding   
         could allow engineers and chemists to develop more efficient   
         catalysts and tune industrial processes -- potentially with enormous   
         energy savings, given that 90% of the products we encounter in   
         our lives are produced, at least partially, via catalysis.   
      
      
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   FULL STORY   
   ==========================================================================   
   In an advance they consider a breakthrough in computational chemistry   
   research, University of Wisconsin-Madison chemical engineers have   
   developed model of how catalytic reactions work at the atomic scale. This   
   understanding could allow engineers and chemists to develop more efficient   
   catalysts and tune industrial processes -- potentially with enormous   
   energy savings, given that 90% of the products we encounter in our lives   
   are produced, at least partially, via catalysis.   
      
      
   ==========================================================================   
   Catalyst materials accelerate chemical reactions without undergoing   
   changes themselves. They are critical for refining petroleum products and   
   for manufacturing pharmaceuticals, plastics, food additives, fertilizers,   
   green fuels, industrial chemicals and much more.   
      
   Scientists and engineers have spent decades fine-tuning catalytic   
   reactions - - yet because it's currently impossible to directly observe   
   those reactions at the extreme temperatures and pressures often involved   
   in industrial-scale catalysis, they haven't known exactly what is taking   
   place on the nano and atomic scales. This new research helps unravel   
   that mystery with potentially major ramifications for industry.   
      
   In fact, just three catalytic reactions -- steam-methane reforming to   
   produce hydrogen, ammonia synthesis to produce fertilizer, and methanol   
   synthesis - - use close to 10% of the world's energy.   
      
   "If you decrease the temperatures at which you have to run these   
   reactions by only a few degrees, there will be an enormous decrease in   
   the energy demand that we face as humanity today," says Manos Mavrikakis,   
   a professor of chemical and biological engineering at UW-Madison who led   
   the research. "By decreasing the energy needs to run all these processes,   
   you are also decreasing their environmental footprint."  Mavrikakis and   
   postdoctoral researchers Lang Xu and Konstantinos G.   
      
   Papanikolaou along with graduate student Lisa Je published news of their   
   advance in the April 7, 2023 issue of the journal Science.   
      
   In their research, the UW-Madison engineers develop and use powerful   
   modeling techniques to simulate catalytic reactions at the atomic   
   scale. For this study, they looked at reactions involving transition metal   
   catalysts in nanoparticle form, which include elements like platinum,   
   palladium, rhodium, copper, nickel, and others important in industry   
   and green energy.   
      
   According to the current rigid-surface model of catalysis, the tightly   
   packed atoms of transition metal catalysts provide a 2D surface that   
   chemical reactants adhere to and participate in reactions. When enough   
   pressure and heat or electricity is applied, the bonds between atoms in   
   the chemical reactants break, allowing the fragments to recombine into   
   new chemical products.   
      
   "The prevailing assumption is that these metal atoms are strongly bonded   
   to each other and simply provide 'landing spots' for reactants. What   
   everybody has assumed is that metal-metal bonds remain intact during the   
   reactions they catalyze," says Mavrikakis. "So here, for the first time,   
   we asked the question, 'Could the energy to break bonds in reactants   
   be of similar amounts to the energy needed to disrupt bonds within   
   the catalyst?'"  According to Mavrikakis's modeling, the answer is   
   yes. The energy provided for many catalytic processes to take place is   
   enough to break bonds and allow single metal atoms (known as adatoms)   
   to pop loose and start traveling on the surface of the catalyst. These   
   adatoms combine into clusters, which serve as sites on the catalyst   
   where chemical reactions can take place much easier than the original   
   rigid surface of the catalyst.   
      
   Using a set of special calculations, the team looked at industrially   
   important interactions of eight transition metal catalysts and 18   
   reactants, identifying energy levels and temperatures likely to form such   
   small metal clusters, as well as the number of atoms in each cluster,   
   which can also dramatically affect reaction rates.   
      
   Their experimental collaborators at the University of California,   
   Berkeley, used atomically-resolved scanning tunneling microscopy to look   
   at carbon monoxide adsorption on nickel (111), a stable, crystalline form   
   of nickel useful in catalysis. Their experiments confirmed models that   
   showed various defects in the structure of the catalyst can also influence   
   how single metal atoms pop loose, as well as how reaction sites form.   
      
   Mavrikakis says the new framework is challenging the foundation of how   
   researchers understand catalysis and how it takes place. It may apply to   
   other non-metal catalysts as well, which he will investigate in future   
   work. It is also relevant to understanding other important phenomena,   
   including corrosion and tribology, or the interaction of surfaces   
   in motion.   
      
   "We're revisiting some very well-established assumptions in understanding   
   how catalysts work and, more generally, how molecules interact with   
   solids," Mavrikakis says.   
      
   Manos Mavrikakis is Ernest Micek Distinguished Chair, James A. Dumesic   
   Professor, and Vilas Distinguished Achievement Professor in Chemical   
   and Biological Engineering at the University of Wisconsin-Madison.   
      
   Other authors include Barbara A.J. Lechner of the Technical University   
   of Munich, and Gabor A. Somorjai and Miquel Salmeron of Lawrence Berkeley   
   National Laboratory and the University of California, Berkeley.   
      
   The authors acknowledge support from the U.S. Department of Energy,   
   Basic Energy Sciences, Division of Chemical Sciences, Catalysis Science   
   Program, Grant DE-FG02-05ER15731; the Office of Basic Energy Sciences,   
   Division of Materials Sciences and Engineering, of the U.S. Department   
   of Energy under contract no. DE-AC02-05CH11231, through the Structure   
   and Dynamics of Materials Interfaces program (FWP KC31SM).   
      
   Mavrikakis acknowledges financial support from the Miller Institute at   
   UC Berkeley through a Visiting Miller Professorship with the Department   
   of Chemistry.   
      
   The team also used the National Energy Research Scientific Computing   
   Center, a DOE Office of Science User Facility supported by the   
   Office of Science of the U.S. Department of Energy under Contract   
   No. DE-AC02-05CH11231 using NERSC award BES- ERCAP0022773.   
      
   Part of the computational work was carried out using supercomputing   
   resources at the Center for Nanoscale Materials, a DOE Office of Science   
   User Facility located at Argonne National Laboratory, supported by DOE   
   contract DE-AC02- 06CH11357.   
      
       * RELATED_TOPICS   
             o Matter_&_Energy   
                   # Chemistry # Physics # Materials_Science #   
                   Organic_Chemistry # Inorganic_Chemistry #   
                   Energy_Technology # Energy_and_Resources #   
                   Engineering_and_Construction   
       * RELATED_TERMS   
             o Catalysis o Autocatalysis o Engineering o Physics o Technology   
             o Radical_(chemistry) o Machine o Catalytic_converter   
      
   ==========================================================================   
   Story Source: Materials provided by   
   University_of_Wisconsin-Madison. Original written by Jason Daley. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Lang Xu, Konstantinos G. Papanikolaou, Barbara A. J. Lechner,   
      Lisa Je,   
         Gabor A. Somorjai, Miquel Salmeron, Manos Mavrikakis. Formation   
         of active sites on transition metals through reaction-driven   
         migration of surface atoms. Science, 2023; 380 (6640): 70 DOI:   
         10.1126/science.add0089   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/04/230406152650.htm   
      
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