Hello, A new project on the LCRC cluster has been requested. Please forward the information on to the LCRC Allocation sub-committee. Applicant's name: Glen Ferguson Applicant's institution: ANL Applicant's division: MSD Project Name: metal_clusters Project title: Catalytic Activity of Subnanometer Metal Clusters Associated funding: Competitive LDRD Other Systems: CNM Carbon Cluster 200,000 core-hours, ALCF Intrepid ~2,000,000 core-hours, EMSL Chinook ~200,000 core-hours Science: The production of classical and next generation fuels using highly active, selective and environmentally safe catalysts is a major challenge that, if met, would provide one approach to meeting future energy needs. This challenge, along with others, is a strong driving force for developing catalysts that are more effective. Toward this goal, there is a desire for the rational design of catalysts with a high degree of selectivity and activity. An important, recently published, advancement is the use of monofunctional surface supported subnanometer metal clusters that catalyze several important reactions of small hydrocarbons, i.e., the oxidative dehydrogen of propane or separately the epoxidation of propene. These advancements open the door for new class of catalysts, constructed by rational design, with high activity and selectivity at relatively low temperatures. Two important directions to explore that may improve and extend the usefulness of these catalysts are the design of bifunctional catalysts and the effect of the surface support on the catalyst’s reactivity. Our work in these areas will focus on the use of both density functional and ab initio calculations to predict the reactivity of bimetallic subnanometer alloys and how the surface support affects their catalytic activity and selectivity. One problem is the prediction of catalysts to perform the stepwise dehydrogenation and partial oxidation of propane to propylene oxide. Currently, there is no bifunctional catalyst that forms partially oxidized propene starting from propane. The possibility of a bifunctional metal alloy cluster catalyst gives a unique opportunity to accomplish this goal in a stepwise fashion exploiting the reactivity of the two catalytic sites of the alloy. The alumina (Al2O3) surface was shown to have a central role in the reactivity of supported Ag3 clusters with propene to form propylene oxide. Specifically, the surface was a key player in the dissociation of oxygen, which is the first step in the partial oxidation of propene. This surface reactivity indic ates the possibility the surface support is important in other reactions. We will therefore investigate other surface supports to understand their effects on the catalytic activity of subnanometer bimetallic alloys. These calculations will be closely coupled with experimental work to produce and test the predicted catalysts and surface supports. Project description: The catalytic properties of small bimetallic alloys will be investigated systematically to find those that exhibit the desired bifunctional capabilities. Initially, the focus will be on monofunctional properties of different single component clusters for propane dehydrogenation and propylene epoxidation. The metals to be considered for propane dehydrogenation will include Ir, Rh, Co, etc. and for propylene epoxidation will include Au, Cu, etc. The reactivity of the subnanometer metal alloys will be studied using the periodic density functional theory implemented in VASP. The size of the bimetallic alloy clusters will be as small as reasonably possible to avoid problems of intractable computational cost. The size of monofucntional catalyst in previous studies was three to eight metal atoms. The periodic calculations will allow for an understanding of the themodynamics and kinetics of the catalytic reactions on various surfaces including alumina (Al2O3 ), magnesium oxide (MgO), zinc oxide (ZnO) and graphene. Once the monofunctional properties of the single component clusters are understood, we will investigate bimetallic catalysts to investigate reaction pathways involving two reaction steps, i.e., dehydrogenation followed by epoxidation We will also investigate other properties of these catalytic materials. To determine how surface defects sites influence reactivity cluster models of the surface-bimetallic cluster complex and supercell calculations will be used. To assess various density functional methods we will use large basis set CCSD(T) calculations with the NWChem program and Gaussian 03 to obtain very accurate values for activation barriers and reaction energies. We will work closely with collaborators in the Material Science Division at Argonne to experimentally test the predictions of our modeling efforts. The following calculations will be performed. a. We will initially carry out an assessment of common density functional methods compared to the gold standard of single-reference ab initio quantum chemical methods, CCSD(T), which is known to be accurate for a broad range of problems. These calculations will use small molecule (CH4, CH3OH) reactions with gas phase Cu4 and Co4 clusters to calculate activation barriers for C−H, O−H, and C−O bond breaking these results can then be compared to those of other common density functional methods such as B3LYP, RPBE, and PW91. These calculations will use the NWChem and Gaussian 09 software packages. These calculations will allow us to find the most appropriate density functional method that balances accuracy and cost for subsequent, more computationally demanding, calculations. b. We will calculate the reaction pathways for propane dehydrogenation and propylene epoxidation on single component subnanometer metal clusters. This will be done using the nudged elastic band method implemented in VASP. The reactions will be carried out with both gas phase and supported metal clusters. It is known that the supports can serve an important role in the dissociation of oxygen on the surface. We are interested in determining if, or how, these other support surfaces can affect the catalytic activity. To calculate the effects of local surface defects small cluster models that reproduce the surface effects will be used. c. We will use the thermodynamics and kinetics information from the single-component modeling to choose likely bimetallic cluster candidates for bifunctional catalysis. The bimetallic clusters of different compositions will be optimized and used to study the reaction pathways for dehydrogenation followed by epoxidation. The calculations will include the effects of the supports in the same manner as the single component clusters. Project URL: Requested allocation: 400,000 Justification: The requester has used 0 hours of their initial startup project. In addition to approving an initial amount, please specify a Category and Subcategory for this project. For a list of the current selection of approved categories, please see: https://wiki.lcrc.anl.gov/wiki/Processes/Categories Once the Allocation committee has approved the project, please go to the Project Management page to create it: https://accounts.lcrc.anl.gov/projects.php Thank You, The LCRC Accounts System