CENTER FOR CATALYTIC SCIENCE & TECHNOLOGY ABSTRACTS. CCST Research Review October 10, 2013 Clayton Hall

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1 CENTER FOR CATALYTIC SCIENCE & TECHNOLOGY ABSTRACTS CCST Research Review October 10, 2013 Clayton Hall

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3 Contents Technical Presentations Peter Gildner The Copper Catalyzed C-Alkylation of Nitroalkanes Gregory Hutchings Electrocatalysis in Lithium-Air Batteries Yannick Kimmel Transition Metal Carbide Supports for Electrochemical Energy Conversion *Nima Nikbin Heterogeneous Acid Catalysis in the Synthesis of Aromatics from Furans Paraskevi Panagiotopoulou Catalytic Transfer Hydrogenation for the Upgrade of Furans Wenchao Sheng Non-precious Metal Catalysts for Hydrogen Oxidation Reaction in Alkaline Electrolytes Jie Zheng PtRu Coated CuNWs as an Efficient Catalyst for Methanol Oxidation Reaction Poster Presentations Christiansen, Matthew Mechanisms of Ethanol Conversion to Ethylene and Diethyl Ether on γ-al2o3 Using Density Functional Theory and Microkinetic Modeling Ipek, Bahar Hydrogen Adsorption by Cu(I)-SSZ-13 Mahmoud, Eyas Renewable Production of Phthalic Anhydride from Biomass-Derived Furan and Maleic Anhydride Mahoney, Elizabeth Rational Design of Electrocatalysts for Fuel Oxidation in Alkaline Environments Medina-Ramos, Jonathan & DiMeglio, John Rational Design of Electrocatalysts for Fuel Oxidation in Alkaline Environments Núñez, Marcel Modeling the Structure Sensitivity of Steam Methane Reforming Rosen, Jonathan Nanoporous Silver as a Highly Selective and Efficient Electrocatalyst for Carbon Dioxide Reduction Swift, T. Dallas, et al. Kinetics of Homogeneous Brønsted Acid- Catalyzed Fructose Dehydration and HMF Rehydration Yonemoto, Bryan Mesoporous Metal Sulfide Electrodes Zhang, Yan Cobalt-based Spinel Nanoparticles as Novel Oxygen Evolution Reaction Catalysts *Abstract for poster and talk are the same

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5 Technical Presentations by CCST Students

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7 The Copper Catalyzed C-Alkylation of Nitroalkanes Peter Gildner, Chemistry & Biochemistry Advisor: Donald A. Watson Nitroalkanes are important intermediates in organic synthesis for the introduction of nitrogen atoms into organic molecules. A highly desirable route to incorporate nitro-groups into alkyl frameworks involves the alkylation of nitronate-anions using simple alkyl electrophiles. Despite the seeming simplicity of this disconnection, reaction conditions allowing for C-alkylation of the nitronate-anion using readily available reagents has remained an open challenge in organic synthesis for more than seventy years. Our group has discovered a simple solution to this long-standing problem in copper-based homogenous catalysts that allow for the high-yielding alkylation of nitronate-anions with several broad classes of commercially available or easily synthesized electrophiles. These operationally simple reactions proceed under mild conditions, show excellent functional group tolerance, and lead to a wide array of complex nitroalkanes in high yields. Additionally, this novel transformation provides facile access to phenethylamines and β-amino acids, two common pharmacophores in many biologically active molecules. The scope and limitation of this method, as well as the future directions of this research program, will be discussed. Peter G. Gildner, Amber A. S. Gietter, Di Cui, and Donald A. Watson. Benzylation of Nitroalkanes Using Copper-Catalyzed Thermal Redox Catalysis: Toward the Facile C-Alkylation of Nitroalkanes. J. Am. Chem. Soc. 2012, 134, ЖЖЖ Peter Gildner is a doctoral student at the University of Delaware under the direction of Professor Donald A. Watson. Peter received his BA in Chemistry and Art from Lafayette College in His organic methodology research in the Donald Watson Laboratory has focused on the discovery and development of a novel mode of reactivity for nitroalkanes, which increases their value as powerful synthetic intermediates.

8 Electrocatalysis in Lithium-Air Batteries Gregory S. Hutchings, Chemical & Biomolecular Engineering Advisor: Feng Jiao As a next-generation lithium battery technology, non-aqueous lithium-air (Li-O 2 ) batteries offer the potential of an order of magnitude increase in specific energy over currently-available, commercialized cells. The reason for this increase is that storage of Li + is not limited by insertion into relatively heavy intercalation materials; instead, oxygen from the atmosphere is reacted with Li + at the cathode interface to form Li 2 O 2. Most practical applications demand long-term cycleability, and a cathode catalyst is required to move towards a rechargeable system with lower overpotentials. 1 Precious metal catalysts are active for redox at the cathode, but inexpensive transition metals and oxides can fill this role instead, and nanostructures of these materials have been shown to improve cycle life and reduce cell overpotentials. The goal of this work is to determine the properties of these cathode materials which optimize performance in the non-aqueous Li-O 2 system, and use this knowledge to synthesize new materials and cathode structures. Manganese oxides, especially α-mno 2, have shown promising activity and are under active investigation. 2 Attaining a thorough understanding of the behavior of these electrocatalysts in operating Li-O 2 cells is critical for future development, and new tools are needed. With a novel in situ X-ray absorption spectroscopy configuration, we have been able to observe oxidation state and coordination environment changes at discrete points in electrochemical cycling. Structural changes can then be related to electrochemical performance to determine which qualities are most desirable for future catalyst design. Additionally, the carbon supports which are typically used in cathode construction have been shown to react with the O 2- reaction intermediate, generating side reaction products and greatly lowering cycle life of the cells. While porous metal and metal oxide structures may be suitable as replacements, few studies have been conducted on these materials in the absence of carbon, and a fundamental characterization of product formation and Li-O 2 electrochemistry on transition metal surfaces is required. With a combination of electron microscopy, electrochemistry, and structural characterization techniques, we have examined the formation of Li 2 O 2 on thin-film transition metal surfaces in order to identify optimal characteristics for designing future cathodes. (1) Ogasawara, T.; Débart, A.; Holzapfel, M.; Novák, P.; Bruce, P. G. Journal of the American Chemical Society 2006, 128, (2) Trahey, L.; Karan, N. K.; Chan, M. K. Y.; Lu, J.; Ren, Y.; Greeley, J.; Balasubramanian, M.; Burrell, A. K.; Curtiss, L. A.; Thackeray, M. M. Advanced Energy Materials 2013, 3, ЖЖЖ Greg Hutchings completed his undergraduate study in chemical engineering at the University of Florida, and is pursuing his PhD in chemical engineering at the University of Delaware, under the direction of Dr. Feng Jiao. His current research interests lie in developing advanced cathode materials for the lithiumoxygen battery system.

9 Transition Metal Carbide Supports for Electrochemical Energy Conversion Yannick C. Kimmel, Chemical & Biomolecular Engineering Advisor: Jingguang G. Chen Interest in the production and utilization of hydrogen as renewable energy source has led to the development of photoelectrochemical (PEC) cells, electrolyzers, and proton exchange membrane (PEM) fuel cells. These devices typically require the use of significant amounts of precious metals such as platinum (Pt) that can greatly increase the cost of these devices. Previous work has found that early transition (Groups 4-6) metal carbides (TMCs) share similar electronic and catalytic properties as the precious Pt-group metals. In addition to the similar chemical properties, the parent metals of TMCs are orders of magnitude more abundant in the earth s crust and less expensive than Pt group metals. Economically, any replacement of Pt with TMCs can result in a great reduction in the catalyst cost. These properties of TMCs make them ideal supports for Pt group metals. Previous work in our research group has found that an ultra-low loading of one monolayer (ML) of Pt can be stable on several TMC supports and as active as bulk Pt for the hydrogen evolution reaction (HER) (1). An electrocatalyst or support must be stable under a given ph and potential to be useful. For pure metals, the stability information can be typically obtained in widely available Pourbaix diagrams. These diagrams do not exist for TMCs, and so there is need to explore the stability of TMCs under a wide range of electrochemical conditions. The first part of this talk will explore pseudo-pourbaix diagrams for TMCs to identify three regions of electrochemical stability by use of chronopotentiometric (CP)-titration measurement (2). The use of density functional theory (DFT) allows for the correlation of electrochemical stability of the TMCs with their binding energies to oxygen. The results show that titanium carbide (TiC) is a highly stable material, and making it a promising support. The second part of this talk will focus on using TiC as a case study for a Pt support for the HER by bridging the activity and stability of predictive theoretical surfaces to ideal thin films that are easily characterized and modified, and then to supported powders that can be used in a PEM device. The results show that low loadings of Pt on TiC result in stable and highly active HER catalysts. (1) D. V. Esposito, S. T. Hunt, Y. C. Kimmel and J. G. Chen, J. Am. Chem. Soc., 2012, 134, (2) M.C. Weidman, D.V. Esposito, Y. Hsu, and J.G. Chen, J. Power Sources, 2012, 202, ЖЖЖ Yannick Kimmel received his B.S. in Chemical Engineering in 2009 from the University of Virginia. He joined the Department of Chemical Engineering at the University of Delaware in the fall of 2009 as a Ph.D. student. He currently lives in New York City and is finishing his doctoral research at Columbia University. Yannick s research interests relate to the development of alternative energy and electrocatalysts.

10 Heterogeneous Acid Catalysis in the Synthesis of Aromatics from Furans Nima Nikbin, Chemical & Biomolecular Engineering Advisors: Stavros Caratzoulas and Dionisios G. Vlachos As available oil resources decline and demand for petroleum-based feedstocks increases, there is growing interest in replacing conventional production routes to fuels and chemicals by sustainable, biomass-based ones. In light of recent success in converting 2,5-dimethylfuran and ethylene to p- xylene 1, via Diels-Alder cycloaddition and dehydration of the resulting cycloadduct over Brønsted or Lewis acidic zeolite Y, we have undertaken the computational investigation of the pathways that lead to aromatics and the byproducts Using the conversion of DMF to p-xylene on zeolite HY as a case study, we rationalize kinetics data using electronic structure calculations. The presence of the zeolitic Brønsted proton in HY increases the Diels-Alder cycloaddition barrier, which therefore likely proceeds uncatalyzed. The cycloadduct, an oxa-norbornene derivative, cannot undergo dehydration in the absence of a catalyst, but is facilely converted to p-xylene on HY. We predict that the rate-limiting step in the conversion of DMF and ethylene to p-xylene on HY is in fact the uncatalyzed cycloaddition reaction. This finding explains why in the reported kinetics of the reaction the rate of p-xylene production was independent of the density of the acid sites whereas the TOF depended strongly the zeolite s Si/Al ratio, i.e., on the density of the active sites 1-2. We also elucidate the most important side reactions: the Brønsted-catalyzed hydrolysis and oligomerization of furans. The fast oligomerization follows the much slower hydrolysis. We have found that site-specific Fukui descriptors as well as proton affinities correlate, quantitatively, with the activation energy associated with the proton attack on the β-c. Since this elementary step limits the overall hydrolysis rate, we assert that the aforementioned descriptors allow for a priori prediction of the protonation barrier and thus screening of furan derivatives according to their propensity to hydrolysis and oligomerization. (1) C. L. Williams, C. Chang, P. T. Do, N. Nikbin, S. Caratzoulas, D. G. Vlachos, R. F. Lobo, W. Fan, P. J. Dauenhauer, Cycloaddition of Biomass-Derived Furans for Catalytic Production of Renewable p-xylene, ACS Catalysis 2 (6), (2012) (2) N. Nikbin, P. T. Do, S. Caratzoulas, R. F. Lobo, P. J. Dauenhauer, D. G. Vlachos, A DFT study of the acid-catalyzed conversion of 2,5-dimethylfuran and ethylene to p-xylene, Journal of Catalysis 297 (2013) ЖЖЖ Nima Nikbin received his Diploma as a Biochemical Engineer from the Department of Biochemical and Chemical Engineering at the University of Dortmund, Germany. In his combined theoretical and experimental thesis he investigated the Affinity Membrane Adsorption for the Purification of Monoclonal Antibodies from Cell Culture Supernatants at Industrial Scale. In September 2009 he began his graduate studies in the Department of Chemical Engineering at the University of Delaware, where he chose to work for Prof. Vlachos. In his current research he uses electronic structure methods and microkinetic modeling to bridge the gap between fundamental understanding and observable process parameters with the ultimate goal of rational catalyst design in the field of renewable energy and resources.

11 Catalytic Transfer Hydrogenation for the Upgrade of Furans Paraskevi (Vivi) Panagiotopoulou, Chemical & Biomolecular Engineering Diminishing fossil resources, in combination with environmental concerns related to reducing atmospheric pollution and global greenhouse gas emissions, dictate the development of alternative renewable sources and new technologies for the production of fuels and chemicals. In this regard, conversion of lignocellulosic biomass is of special interest, since it is widely available around the world at a relatively low cost 1. However, biomass is highly oxygenated and highly functionalized, and therefore, the energy density should be increased and the contained reactive oxygenated organic compounds should be selectively converted to high value chemicals at high yields. This can be achieved by catalytic hydrodeoxygenation of furanic components. Biomass derived furfural, produced by acidic degradation of hemicelluloses, is an important intermediate for a number of potential biofuels components and chemicals. Selective hydrogenolysis of furfural is a vital way to transform it into more valuable products such as furfuryl alcohol (FA), tetrahydrofurfuryl alcohol (THFA), methyl furan (MF) or cyclopentanone. Among the various products, MF is attractive, since not only has intrinsically good fuel properties but also can be considered an archetypical product of the desired reaction paths in bio-oil upgrading. Moreover, one of its two reactive a-positions is protected by the unreactive methyl group, which could reduce the chance of side reactions. In the present work the production of MF through catalytic transfer hydrogenation of furfural has been investigated in the liquid phase over Ru/C catalyst. Experiments have been conducted in the temperature range of o C in a Parr batch reactor, with the use of an alcohol solution of furfural. It has been found that the reaction of furfural hydrogenation in the liquid phase proceeds toward production of FA, which is further hydrogenated to MF. Small amounts of furan and traces of THFA are also produced via furfural decarbonylation and FA hydrogenation, respectively. Production of MF is enhanced with increasing reaction temperature and/or reaction time. Optimum results have been obtained after 10 h of reaction at 180 o C, where furfural conversion and MF yield reach 100% and 76%, respectively. Mechanistic aspects of the reaction have been investigated by analysing the evolution of reaction intermediates and final products. Production of intermediates, as well as MF, are taking place faster when FA is used as reactant, rather than furfural, via intermediate production of FA. Catalyst recycling experiments over spent Ru/C catalyst showed that although furfural conversion is not decreased significantly, FA yield increases at the expense of MF. However, the initial catalytic activity and selectivity is completed regained after regeneration. (1) D.M. Alonso, S.G. Wettstein, J.A. Dumesic, Chem. Soc. Rev. 41 (2012) ЖЖЖ Paraskevi (Vivi) Panagiotopoulou is a postdoctoral researcher at the Catalysis Center for Energy Innovation (CCEI) in the Department of Chemical and Biomolecular Engineering of the University of Delaware. She received her diploma in Chemical Engineering in 2001 and her M.Sc and Ph.D. in Chemical Engineering in 2006 from the University of Patras, Greece. From 2006 to 2012 she worked at the laboratory of Heterogeneous Catalysis at the Department of Chemical Engineering of the University of Patras. Her research activities are focused in the area of heterogeneous catalysis and, especially, in materials synthesis and characterization, catalyst development and evaluation, and investigation of reaction kinetics and mechanisms, with emphasis given in environmental and energy-related applications.

12 Non-precious Metal Catalysts for Hydrogen Oxidation Reaction in Alkaline Electrolytes Wenchao Sheng, Chemical & Biomolecular Engineering Advisors: Yushan Yan and Jingguang G. Chen Low-temperature hydrogen fuel cells show great promise for highly efficient and environmentally friendly energy conversion. 1 In addition to the 300 ~ 400 mv overpotential caused by the sluggish oxygen reduction reaction (ORR) at the cathode in both acidic and alkaline media, slow hydrogen oxidation reaction (HOR) on Pt in alkaline electrolytes compared to that in acids imposes extra cell voltage loss, which in turn requires higher Pt loading on the anode. 2 Therefore, the demand keeps increasing for non-precious electrocatalysts for the HOR in alkaline electrolytes in order to reduce the overall catalyst cost and make alkaline membrane fuel cells more practical. Through the study of the reverse reaction i.e., hydrogen evolution reaction (HER) on a wide range of metal surfaces in base, we found the exchange current densities at the reversible hydrogen potential correlated to the calculated hydrogen binding energies (HBE) of these metal surfaces via a volcano relationship. 3 This finding suggests that HBE values can be used as a reaction descriptor for designing and searching for novel electrocatalysts for the HER/HOR in base. We calculated the HBE of Ni-based multimetallic surfaces and found that CoNiMo, had much reduced HBE value compared to Ni. We subsequently synthesized CoNiMo by electrodeposition and evaluated their HOR performance at different temperatures. The results demonstrate an order of magnitude enhancement of HOR specific kinetic activity of CoNiMo than Ni, probably ascribed to its weakened HBE. This promising material will greatly mitigate the catalyst cost issue raised by higher Pt loading in alkaline electrolytes for maintaining similar anode performance as in acids, which will facilitate advancing the alkaline or alkaline membrane fuel cell technology. (1) H. A. Gasteiger, S. S. Kocha, B. Sompalli and F. T. Wagner, Applied Catalysis B-Environmental, 56, 9 (2005). (2) W. C. Sheng, H. A. Gasteiger and Y. Shao-Horn, Journal of the Electrochemical Society, 157, B1529 (2010). (3) W. C. Sheng, M. N. Z. Myint, J. G. Chen and Y. S. Yan, Energy and Environmental Science, 6, 1509 (2013). ЖЖЖ Wenchao Sheng graduated from the department of chemistry at MIT in She is currently a postdoctoral researcher in the department of chemical and biomolecular engineering at the University of Delaware. Her research focuses on the fundamental understanding of the electrochemical processes and development of novel materials for electrochemical energy storage and conversion. She received her Bachelor s and Master s degrees from Tongji University in China.

13 PtRu Coated CuNWs as an Efficient Catalyst for Methanol Oxidation Reaction Jie Zheng, Chemical & Biomolecular Engineering Advisor: Yushan Yan Direct methanol fuel cells (DMFCs) are an attractive alternative to hydrogen-fueled proton exchange fuel cells for powering portable electronic devices because of their high energy density and ease of fuel transportation and storage. While nearly zero overpotential is observed for hydrogen oxidation reaction in acid, large overpotential exists even on the state-of-the-art PtRu/C MOR catalyst. 1 Therefore, developing catalysts with high MOR activity is of great importance. MOR is known to be a structure sensitive reaction with Pt(110) facet showing the highest specific activity among low index surfaces. 2 One-dimensional (1D) nanostructures such as nanowires, nanotubes and nanorods often have the preferential exposure of certain facets which will enhance the MOR activity. 3. Studies have shown that platinum nanotubes (PtNTs) have higher MOR specific activity than platinum nanoparticles supported on carbon (Pt/C) 4, which might be attributed to the exposure of (110) facets of PtNTs. However, it remains unclear whether 1D PtRu nanostructures have higher MOR activity. In our work, we synthesized one-dimensional PtRu coated Cu nanowires (PtRu/CuNWs) via partial galvanic displacement of CuNWs by Pt and Ru precursors. By varying the Pt and Ru precursor ratio, PtRu/CuNWs with different Pt:Ru ratio were obtained. Their MOR activities were evaluated by cyclic voltammetry using rotating disk electrodes. By varying the Pt:Ru ratio, we achieved higher specific and mass activity on PtRu/CuNWs compared with a commercial MOR catalyst PtRu/C (HiSPEC 12100). The thin coating of PtRu on CuNWs reduced the amount of precious metals used, enabling the enhancement of mass activity. (1) A. Hamnett, in Handbook of Fuel Cells, John Wiley & Sons, Ltd (2010). (2) E. Herrero, K. Franaszczuk and A. Wieckowski, The Journal of Physical Chemistry, 98, 5074 (1994). (3) C. Koenigsmann and S. S. Wong, Energy & Environmental Science, 4, 1161 (2011). (4) S. M. Alia, G. Zhang, D. Kisailus, D. Li, S. Gu, K. Jensen and Y. Yan, Advanced Functional Materials, 20, 3742 (2010). ЖЖЖ Jie Zheng is currently a 4 th year Ph.D. student working in Dr. Yushan Yan s research group in department of chemical and biomolecular engineering at University of Delaware. Her research interests are to develop electrocatalysts for fuel cells. She received her bachelor s degree in Chemical Engineering from Zhejiang University, China in 2010.

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15 Poster Presentations by CCST Students

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17 Mechanisms of Ethanol Conversion to Ethylene and Diethyl Ether on γ-al 2 O 3 Using Density Functional Theory and Microkinetic Modeling Matthew A. Christiansen, Chemical & Biomolecular Engineering Advisor: Dionisios G. Vlachos There is substantial ongoing research into the production of fuels and chemicals from biomassderived feedstocks. These feedstocks are often over-functionalized and must have some chemical functionality removed via catalytic upgrade (e.g., dehydration, hydrodeoxygenation, etc.). Identifying materials to execute such transformations and understanding the catalytic cycle will enable the rational development of superior catalysts. Metal oxides are an important class of materials that catalyze dehydration reactions, but there is little mechanistic understanding of the role that they play in the catalytic conversion of oxygenated hydrocarbons and sugars, including how they affect selectivity. For the specific case of alcohol dehydration and etherification over γ-al 2 O 3, the reaction mechanisms are still under debate despite decades of study. Part of the complexity arises because bulk Al atoms occupy both tetrahedral and octahedral sites, and consequently exposed surface Al sites can display three-, four-, or five-fold coordination. In addition, γ-al 2 O 3 nanoparticles expose various facets including (100), (110) and (111). In order to delve deeper into the fundamentals of reaction kinetics and selectivity for this system, we used periodic density functional theory (DFT) calculations and microkinetic modeling to explore the reactions of ethanol on a diversity of Al surface sites and on different γ-al 2 O 3 facets. DFT calculations demonstrate that ethanol is most stable when bound to a surface Al site, pointing to the role of Lewis acidity in these reactions. Multiple pathways for dehydration were explored including sequential and concerted bond-breaking mechanisms. A concerted elimination (E2) pathway was the most energetically favorable pathway, consistent with earlier results using an Al 8 O 12 cluster 1 and with an observed C-H kinetic isotope effect. 2 We also identified new pathways for diethyl ether formation; a bimolecular nucleophilic substitution (S N 2) mechanism was most favorable. The rate expression for ethylene formation requires both an adsorbed ethanol and a vacant surface O site, while ether formation requires an adsorbed ethanol and an adsorbed ethoxy. These two pathways form a mechanistic branching point originating from adsorbed ethanol. The lowest-energy barriers for the two pathways are similar on each of the (100), (110), and (111) facets; thus the relative coverages of ethoxy and vacant O sites critically affect selectivity. In order to explicitly account for the effect of coverage on the reaction rates and compare to experimental reaction orders, 2 a microkinetic model was developed using data from the (111) facet. The model successfully replicates key experimental trends with minimal parameter adjustment. Ethoxy, OH, and H are the most abundant intermediates on the catalyst surface. O-H bond dissociation/ formation reactions are equilibrated, while the E2 and S N 2 mechanisms are irreversible and ratecontrolling. These results have answered key questions about (1) the mechanisms for alcohol conversion on γ-al 2 O 3 and (2) the origin of observed selectivity trends. They are also leading to additional insights about reactions on other metal oxides, suggesting that there may be a common alcohol dehydration mechanism on solid Lewis acid catalysts. (1) S. Roy, et al. ACS Catal. 2012, 2 (9), (2) J.F. DeWilde, et al. ACS Catal. 2013, 3 (4),

18 Hydrogen Adsorption by Cu(I)-SSZ-13 Bahar Ipek, Chemical & Biomolecular Engineering Advisor: Raul F. Lobo Physical adsorption of hydrogen on to lightweight porous materials is a good alternative to recent hydrogen storage techniques since these adsorbents have large pore volumes and surface areas where they can reversibly adsorb hydrogen. Majority of the porous adsorbents such as metal organic frameworks and alkali exchanged zeolites suffer from low adsorption enthalpies which renders cryogenic temperatures and/or high pressures necessary for hydrogen adsorption at reasonable amounts. Garrone et al. have calculated an optimum hydrogen adsorption enthalpy of 22 kj/mol required for high adsorption amounts at 30 bar and easy desorption at 1.5 bar, 300 K. 1 Cu(I)-SSZ-13 zeolite, with monoatomic Cu(I) cations located 1.2 Å above each 6 member ring of the CHA framework gave an hydrogen adsorption enthalpy of 19 kj/mol which shows the highest hydrogen adsorption capacity (0.21 mmol H 2 /g) at 300 K and 1 bar when compared to metal organic frameworks, alkali metal exchanged zeolites and Cu(I) exchanged zeolites with different frameworks. In this superior hydrogen adsorption capacity of Cu(I)-SSZ-13, size of the CHA framework, Cu(I) concentration and location of Cu(I) cations are the most significant factors since Cu(I) sites are the main adsorption sites for hydrogen. In this investigation, effect of Cu(I) concentration and location on hydrogen adsorption amounts at 77 and 303 K were studied. Powder diffraction experiments at 10 and 300 K revealed a 1.1 Å difference in the location of the Cu (I) cation with increasing temperature. Cu(I) cation, mostly shielded by three oxygen atoms that it has been coordinated to, cannot completely interact with hydrogen molecules at 10 K. However at room temperature, hydrogen adsorption is favored due to more exposed position of Cu(I) cations in the CHA cage where they can freely interact with hydrogen. (1) Garrone, E.; Bonelli, B.; Arean, C. O. Chemical Physics Letters 2008,456, 68

19 Renewable Production of Phthalic Anhydride from Biomass-Derived Furan and Maleic Anhydride Eyas Mahmoud, Chemical & Biomolecular Engineering Advisor: Raul F. Lobo A route to renewable phthalic anhydride (2-benzofuran-1,3-dione) from biomass-derived furan and maleic anhydride (furan-2,5-dione) is investigated. Furan and maleic anhydride were converted to phthalic anhydride in two reaction steps: Diels Alder cycloaddition followed by dehydration. Excellent yields for the Diels-Alder reaction between furan and maleic-anhydride were obtained at room temperature and solvent-free conditions (SFC) yielding 96% exo-4,10-dioxatricyclo[ ]dec-8-ene-3,5-dione (oxanorbornene dicarboxylic anhydride) after 4 hrs of reaction. It is shown that this reaction is resistant to thermal runaway because its reversibility and exothermicity. The dehydration of the oxanorbornene was investigated using mixed-sulfonic carboxylic anhydrides in methanesulfonic acid (MSA). An 80% selectivity to phthalic anhydride (87% selectivity to phthalic anhydride and phthalic acid) was obtained after running the reaction for 2 hrs at 298 K to form a stable intermediate followed by 4 hrs at 353 K to drive the reaction to completion. The structure of the key stable intermediate was determined. This result is much better than the 11% selectivity obtained in neat MSA using the same conditions.

20 Rational Design of Electrocatalysts for Fuel Oxidation in Alkaline Environments Elizabeth G. Mahoney, Chemical & Biomolecular Engineering Advisors: Jingguang Chen and Yushan Yan With the rising concern of climate change, an increasing amount of research has been applied to improving sources of renewable energy. Electrochemical power sources such as fuel cells have been cited as promising replacements for combustion-based technologies due to their high efficiencies and power densities. The advent of proton exchange membranes warranted the development of solid state fuel cells that boasted CO 2 -free exhaust from the oxidation of hydrogen gas. However, proton exchange membrane fuel cells have encountered obstacles in their commercial application due to the difficulty of producing hydrogen from environmentally-friendly sources, the lack of efficient hydrogen storage systems, and the prohibitive cost and scarcity of platinum electrocatalysts. New systems have been explored that exploit hydrocarbon fuels such as ethylene glycol, which can be produced from CO 2 -neutral feedstocks 1, but the economic problems posed by the requirement of platinum catalysts in acidic media remain a limiting factor. One way to decrease the cost of fuel cells is to transition to an alkaline environment by utilizing hydroxide exchange membranes instead of proton exchange membranes. A wider range of catalytic materials are stable at high ph, which encourages the minimization or even eradication of platinum group metal catalysts in the fuel cell. However, the hydrogen oxidation reaction (HOR) kinetics slow considerably in alkaline electrolytes and platinum still retains the highest activity compared to less expensive metals. 2 The alkaline HOR electrocatalytic mechanism is largely unstudied, though it has been shown that adsorbed hydroxyl may play a role in the reaction kinetics. 3 Understanding the reaction mechanism on platinum could lead to the further development of first-row transition metal catalysts, which are less expensive. Accordingly, this study uses platinum monolayer catalysts to explore the effect of hydroxyl binding energy on the HOR kinetics in alkaline conditions. Platinum monolayer catalysts have been previously used to improve the activity of hydrogen evolution and oxygen reduction in acidic media by tuning reactant binding energy on the catalyst surface. 4,5 In addition to testing these catalysts for alkaline HOR, their activity toward the alkaline oxidation of alcohols is also investigated and compared to the same reactions in acidic conditions. By using a monolayer of platinum supported on gold, near equivalent activity to bulk platinum is measured for the oxidation of hydrogen and ethylene glycol. DFT-calculated binding energies of hydrogen and hydroxyl are calculated for the bulk platinum, bulk gold, and bulk platinum monolayer on gold surfaces to establish trends among these reactions. (1) Ji, N., Zheng, M., Wang, A., Zhang, T. & Chen, J. G. Nickel-promoted tungsten carbide catalysts for cellulose conversion: effect of preparation methods. ChemSusChem 5, (2012). (2) Sheng, W., Myint, M. N. Z., Chen, J. & Yan, Y. Trends of the Hydrogen Evolution/Oxidation Reaction in Alkaline Medium. Energy & Environmental Science (2013). (3) Strmcnik, D. et al. Improving the hydrogen oxidation reaction rate by promotion of hydroxyl adsorption. Nature Chemistry 1 7 (2013). doi: /nchem.1574 (4) Esposito, D. V. & Chen, J. G. Monolayer platinum supported on tungsten carbides as low-cost electrocatalysts: opportunities and limitations. Energy & Environmental Science 4, 3900 (2011). (5) Zhang, J., Vukmirovic, M. B., Xu, Y., Mavrikakis, M. & Adzic, R. R. Controlling the catalytic activity of platinum-monolayer electrocatalysts for oxygen reduction with different substrates. Angewandte Chemie (International ed. in English) 44, (2005).

21 Highly Efficient CO 2 Reduction Using a Bismuth Carbon Monoxide Evolving Catalyst Jonnathan Medina-Ramos and John L. DiMeglio, Chemistry and Biochemistry Advisor: Joel Rosenthal Heterogeneous electrochemical reduction of CO 2 to CO, which can be coupled to liquid fuel production, provides a pathway to address current issues in solar energy storage. Over the last 40 years, much effort has been devoted to the development of heterogeneous electrocatalysts that can promote the conversion of CO 2 to CO, however, only noble metal based materials have been found to drive this process with high current densities and energy efficiency. In recent work, we have shown that properly designed bismuth based cathodes provide an inexpensive alternative to precious metals for CO 2 electrolysis. Such systems can be generated via electrochemical deposition of a Bi 3+ /Bi 0 catalyst onto conducting substrates. In the presence of ionic liquids, this bismuth based material functions as a carbon monoxide evolving catalyst and can reduce CO 2 to CO at overpotentials below 0.2 V with energy efficiencies as high as 85%.

22 Modeling the Structure Sensitivity of Steam Methane Reforming Marcel Núñez, Chemical and Biomolecular Engineering Advisor: Dionisios Vlachos Steam methane reforming (SMR) is an important process for the industrial production of syngas. The structure sensitivity of SMR on metal nanoparticles remains unresolved from a modeling standpoint, as computational studies have been unable to reproduce structural trends seen in experiments. A hierarchical multiscale modeling framework is employed to develop a model for SMR which takes into account nanoparticle structure and closes the gap between model predictions and experimental data. Literature DFT data is used to parameterize a graph theoretical kinetic Monte-Carlo (KMC) simulation of the SMR chemistry on platinum surfaces. KMC is capable of explicitly accounting for lattice structure in the model by including the spatial distribution of different site types. Simulation results show which sites participate in various elementary reactions. It is found that the under-coordinated step sites contribute not only to the rate-determining methane adsorption step, but also to the direct addition of atomic oxygen to carbon.

23 Nanoporous Silver as a Highly Selective and Efficient Electrocatalyst for Carbon Dioxide Reduction Jonathan Rosen, Chemical & Biomolecular Engineering Advisor: Feng Jiao Due to rising energy demand and evidence of the environmental effects of CO 2 emissions, much research has focused on producing and storing energy from renewable sources. An efficient and selective process for the conversion of CO 2 to CO or other reduced products could allow for the widespread production of liquid fuels. Coupled with renewable energy sources, these processes could help solve the large scale storage issue of renewable energies while creating a carbon neutral energy source easily integrated into the current energy infrastructure. 1 To date, researchers have identified several potential catalysts such as Cu, Ag, Au, and Zn that are able to reduce CO 2 electrochemically in aqueous electrolytes. Precious metal catalysts such as Au and Ag are able to reduce CO 2 selectively to CO and are of interest, while Cu and Zn yield a mixture of formate, hydrogen, CO, alcohols, and other hydrocarbons. 2 Silver (Ag) is an interesting CO 2 reduction catalyst due to the fact that it is able to convert CO 2 almost exclusively to CO at a fraction of the cost of gold, albeit requiring a larger overpotential. 2 Reducing the overpotential needed to drive the reduction of CO 2 on silver will help improve the economic prospects of such technologies. Here, we report that a nanoporous Ag electrocatalyst is able to electrochemically reduce CO 2 to CO with a ~92% selectivity at a rate (i.e. current) of over 3000 times higher than its polycrystalline counterpart under a moderate overpotential of less than 0.50 V. Such an exceptionally high activity is a result of a large electrochemical surface area (ca. 150 times larger) and intrinsically high activities (ca. 20 times higher) compared to polycrystalline Ag. The improved intrinsic activity may be a result of higher CO 2 reduction activity on stepped surfaces, which has been observed in single crystal studies. 3 The presence of this curved surface is much higher in nanoporous silver than the flat surface most commonly found in polycrystalline silver resulting in an at least 20 times difference in activities. (1)Gattrell, M.; Gupta, N.; Co, A. Journal of Electroanalytical Chemistry 2006, 594, 1. (2)Hori, Y. Modern Aspects of Electrochemistry 2008, 42, 89. (3)Hoshi, N.; Kato, M.; Hori, Y. Journal of Electroanalytical Chemistry 1997, 440, 283.

24 Kinetics of Homogeneous Brønsted Acid- Catalyzed Fructose Dehydration and HMF Rehydration T. Dallas Swift, Christina Bagia, Vinit Choudhary, Vladimiros Nikolakis, Chemical & Biomolecular Engineering Advisor: Dionisios G. Vlachos Furans are a class of chemicals readily obtained from biomass that can be used as intermediates for the production of valuable fuels and chemicals. One important member of this class of compounds, 5-hydroxymethylfurfural (HMF), can be derived from hexose sugars through Brønsted acid catalyzed dehydration. Fructose, a ketose sugar, is especially selective for HMF production. However, several side reactions also occur in this same acidic medium leading to the irreversible formation of insoluble humins and other organic compounds, primarily formic and levulinic acids. Understanding the effect of process parameters on these reactions is therefore important for the selective production of HMF. The aim of the present work is to better understand fructose dehydration and HMF rehydration kinetics through the development of a skeleton model that parsimoniously incorporates essential physics and integrates experimental and computational insights. While there have been several efforts to study the kinetics of hexose dehydration at different temperatures or ph values 1-8, these efforts rely on a phenomenological approach that fails to include known phenomena. The model developed here addresses explicitly for the first time (1) the tautomeric distribution of fructose, (2) the increased fraction of formic acid compared to levulinic acid when starting from fructose 9, and (3) the correct rate-limiting step as revealed by first-principles computational studies and kinetic isotope experiments. We conducted 45 different kinetic experiments with varying concentrations of either fructose or HMF comprising over 1500 data points in total between C and buffered ph between These data are fitted simultaneously using least-squares nonlinear regression to determine the pre-exponentials and activation energies of all reactions considered with constraints from our prior first-principles modeling. In summary, the present work brings together a comprehensive experimental data set and physical insights to develop a model that describes the production of HMF from fructose while accounting for experimental and computational advances in the field. (1) Kuster, B. F. M. Carbohydr. Res. 1977, 54, 177. (2) Kuster, B. F. M.; Temmink, H. M. G. Carbohydr. Res. 1977, 54, 185. (3) Khajavi, S. H.; Kimura, Y.; Oomori, T.; Matsuno, R.; Adachi, S. J. Food Eng. 2005, 68, 309. (4) Girisuta, B.; Janssen, L. P. B. M.; Heeres, H. J. Chem. Eng. Res. Des. 2006, 84, 339. (5) Girisuta, B.; Janssen, L. P. B. M.; Heeres, H. J. Green Chem. 2006, 8, 701. (6) Asghari, F. S.; Yoshida, H. Ind. Eng. Chem. Res. 2007, 46, (7) Kuster, B. F. M.; Van Steen, H. J. C. D. Starch - Stärke 1977, 29, 99. (8) Baugh, K. D.; McCarty, P. L. Biotechnol. Bioeng. 1988, 31, 50. (9) Kuster, B. F. M.; Tebbens, L. M. Carbohydr. Res. 1977, 54, 158.

25 Mesoporous Metal Sulfide Electrodes Bryan T. Yonemoto, Chemical & Biomolecular Engineering Advisor: Feng Jiao Mesoporous silica templates such as SBA-15 or KIT-6 have been used very effectively to make nanocast battery electrode materials that show significant performance improvements bulk, nonporous morphologies. Some good examples are the use of CMK-3 in the Li-S battery 1 and the preparation of beta-mno 2 electrodes from KIT-6 2. While metal oxides and carbon inverse structures have seen extensive investigations, relatively few reports about mesoporous transition metal sulfides, via any preparation method, are available in the literature. This is unfortunate because many metal sulfides exhibit very different material properties compared to metal oxides. In this investigation we report the characterization and electrochemistry of a mesoporous iron sulfide material. Low angle powder x-ray diffraction, gas adsorption and transmission electron microscopy are used to characterize the mesoporous material. Wide angle powder x-ray diffraction is used to confirm the phase transformation from Fe 2 O 3 to FeS 2. Finally, galvanostatic charge and discharge studies are performed to analyze the electrochemical performance of the iron sulfide product. Our hope is that this new synthesis strategy is the first of many mesoporous metal sulfide battery electrodes. (1) Ji, X. L.; Lee, K. T.; Nazar, L. F. Nature Materials 2009, 8, 500. (2) Jiao, F.; Bruce, P. G. Advanced Materials 2007, 19, 657.

26 - Cobalt-based Spinel Nanoparticles as Novel Oxygen Evolution Reaction Catalysts Yan Zhang, Chemical & Biomolecular Engineering Advisor: Feng Jiao The limited supply of fossil fuels and greenhouse gas emissions (such as CO 2 ) have made the development of sustainable and clean energy sources urgent and critical to our society. Solar energy, which is abundant compared to the global primary energy consumption today, is viewed as a promising alternative energy source. 1 The photocatalytic device that utilizes solar energy to convert carbon dioxide and water to make liquid fuels is an ideal energy solution, not only because the current infrastructure is designed to transport and store liquid fuels, but also because such devices consume CO 2 during fuel production. Currently, photocatalytic solar fuel production is not ready for large scale practical applications due to the absence of non-precious, efficient and robust material as oxygen evolution reaction (OER) catalyst. Co 3 O 4 spinel material is one of the most promising candidates as it has been able to catalyze the reaction with good turnover frequency (TOF) and relatively low cost. 2 But the activity of this material is limited by the non-ideal oxygen binding energy according to computational results. 3 To improve the catalytic activity of the Co 3 O 4 spinel material and to further investigate the origin of the activity, we designed and synthesized manganese and nickel substituted cobalt oxide spinel nanoparticles and studied the effect of metal substitutions in spinel structure on the OER catalytic performance. The manganese substituted nanoparticles showed a better activity compared to the pure cobalt oxide ones. 4 (1) D. G. Nocera, M. P. Nash, PNAS 2007, 103, (2) F. Jiao, H. Frei, Angewandte Chemie (International ed. in English) 2009, 48, (3) I. C. Man, H.-Y. Su, F. Calle-Vallejo, H. a. Hansen, J. I. Martínez, N. G. Inoglu, J. Kitchin, T. F. Jaramillo, J. K. Nørskov, J. Rossmeisl, ChemCatChem 2011, 3, (4) Y. Zhang, J. Rosen, G. Hutchings, F. Jiao, Catalysis Today 2013, accepted.

27 CCST Faculty NAME Douglas J. Buttrey Wilfred Chen Douglas J. Doren Feng Jiao Michael T. Klein Raul F. Lobo Joel Rosenthal S. Ismat Shah Andrew V. Teplyakov Klaus H. Theopold Dionisios G. Vlachos Donald A. Watson Yushan Yan Bingjun Xu The University of Delaware is an equal opportunity/affirmative action employer. For the University s complete non-discrimination statement, please visit

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