Meeting Program — January 2015
Dr. Julia Valla
Chemical and Biomolecular Engineering Department
University of Connecticut, Storrs, CT
Thermochemical conversion of biomass to energy, fuels and chemicals is an attractive technology for the transition from fossil resources to a renewable-based economy. Catalytic Fast Pyrolysis (CFP) of biomass is a particularly interesting technology for biomass conversion considering the already extensive infrastructure for hydrocarbons production. However, many challenges remain unsolved before the deployment of the biomass CFP can be realized, including: a) char and coke formation, which causes rapid catalyst deactivation; and b) high oxygen content in the bio-oil, which makes it incompatible with today’s hydrocarbon fuels. With respect to the first challenge, it is imperative to first understand the origin and the formation of char and coke during CFP. Considering the second challenge, it is important to understand which catalyst properties can enhance the deoxygenation reactions and increase the bio-oil selectivity to hydrocarbons. ZSM-5 zeolites have been recognized as one of the most promising zeolites for CFP due to their shape selectivity and their deoxygenation ability. However, their micropore structure can limit the accessibility of heavy compounds to the active sites of their framework. Modifying the zeolite pore architecture to create hierarchical structures could provide a solution to this challenge. Furthermore, the CFP process design itself (in situ or ex situ) can alter the product yield and selectivity and, thus, the bio-oil quality. During this presentation we will discuss how the zeolite properties and location within the CFP process (in situ or ex situ) can affect the coke/char formation and the deoxygenation reactions for enhanced bio-oil quality.
Ioulia (Julia) Valla is an Assistant Professor in the Chemical & Biomolecular Engineering Department at the University of Connecticut. She received her PhD in the field of the development of new zeolites for the decomposition of sulfur compounds in naphtha and the production of environmental gasoline from the Aristotle University of Thessaloniki in Greece. She has served in a leadership role with Rive Technology, Inc. on the commercialization of a novel zeolite with ordered mesoporous structure for refinery applications. Dr. Valla’s research focuses on the modification of zeolites structure and their application in catalysis, adsorption and energy. She is the author/co-author of 9 papers in peer-reviewed journals, 1 book chapter and 2 patents. Dr. Valla is the recipient of the European Award “RUCADI, Recovery and Utilization of Carbon Dioxide” for her study on the role of CO2 on the reforming of natural gas for the production of methanol. At the University of Connecticut, Dr. Valla received an award sponsored by the National Science Foundation for the study “Turning Tars into Energy: Zeolites with Hierarchical Pore Structure for the Catalytic Removal of Tars”. The study is focused on a novel application of hierarchically structured mesoporous bifunctional catalysts for the thermochemical upgrading of undesirable tars from biomass pyrolysis or gasification to valuable hydrocarbons.
Meeting Program — September 2014
Emission Control Technologies
Johnson Matthey Inc.
Abstract — Reduction of NOx emissions from lean-burn engine exhaust has been a main topic of environmental catalysis in the past 20 years. The challenge is the selective conversion of a low concentration of NOx (~100 ppm) in the presence of large excess of O2 (~10%). Although zeolite supported transition metal catalysts were identified in early 1990s as promising catalysts, such a technology was not implemented till recently.
Early studies mainly focused on the development of zeolite supported transition metal, primarily Cu and Fe, catalysts for the selective catalytic reduction of NOx with hydrocarbons (HC-SCR). Even though the HC-SCR technology has been considered as the “holy grail” of automotive catalysis, technical challenges on the activity, selective and durability of the catalysts were recognized to be difficult to overcome for the technology to be implemented into real world applications. However, the vast amount of research work, especially the fundamental studies on the reaction and the catalyst deactivation mechanisms, demonstrated that the activity and selectivity of this type of catalysts can be drastically improved if an alternative reductant, NH3, is available in the feed.
Extensive investigations on the selective catalytic reduction of NOx with NH3 (NH3-SCR) began in the middle 2000s aimed to enable diesel powered vehicles to meet the US EPA 2007/2010 emission regulations. Both Cu and Fe catalysts were considered. Zeolite supported Cu SCR catalysts are more active at low temperature, thus more attractive for applications with low exhaust temperature. The conventional medium-pore zeolite (10-ring, such as ZSM-5) or large-pore zeolite (12-ring, such as beta) supported Cu catalysts, however, cannot meet the long-term durability requirements. To overcome this major technical hurdle, small-pore zeolite (8-ring) supported Cu catalysts were invented. On the other hand, zeolite supported Fe SCR catalysts are more selective in utilizing NH3 for NOx reduction at high temperatures but show a strong dependence on the NO to NO2 ratio in the feed gas at low temperatures. System approaches were developed to enhance the low temperature SCR activity of the Fe SCR catalysts. As such, both Cu and Fe SCR catalysts were successfully commercialized and applied on lean-burn diesel vehicles meeting the stringent US EPA 2010 emission standards.
Biography — Dr. Hai-Ying Chen is a Scientific and Product Development Manager at Johnson Matthey, where he leads a team of scientists to develop advanced emission control catalysts and technologies for both gasoline engine and diesel engine powered vehicles to meet the government emission regulations.
Dr. Chen received his Ph.D. in Chemistry from Fudan University, China. He has published more than 50 technical papers in peer-reviewed journals and holds 14 US/international patents. He received the Top Cited Article Award by Catalysis Today for articles published in 1998, and was a recipient of the American Chemical Society Award for Team Innovation in 2009. He was named as the 2014 Herman Pines Award in Catalysis by the Chicago Catalysis Club and the 2014 Catalysis Club of Philadelphia Award by the Catalysis Club of Philadelphia.
Meeting Program — April 2014
Gabor Kiss, Stuart Soled, Chris Kliewer
ExxonMobil Res. and Eng. Co.
Abstract — In this paper, we describe three intrinsic deactivation modes observed in experimental cobalt Fischer-Tropsch synthesis catalysts: cobalt oxidation reversible by mild hydrogen treatment, cobalt agglomeration, and cobalt-support mixed oxide formation. All three mechanisms involve redox transformation of the catalytically active cobalt metal.
Biography — Gabor Kiss received his M.Sc. in chemical engineering from the University of Veszprem (now Pannon University), Hungary, in 1981. He worked in the Hungarian oil industry for eight years before enrolling the graduate school at the University of Miami. After receiving his Ph.D. in chemistry in 1993, he accepted a position at Exxon’s (now ExxonMobil) Corporate Research Laboratories in Clinton, NJ, where he is currently a Sr. Scientific Associate. His research interests include the kinetics, thermodynamics, and mechanism of both homogeneous and heterogeneous catalytic processes. He has published 26 peer-reviewed papers and has 38 patents.
2014 Spring Symposium
Abstract — Not Available.
Biography — Not Available.
2014 Spring Symposium
Fabio H. Ribeiro*1, W. Nicholas Delgass1, William F. Schneider2, Jeffrey T. Miller3, Aleksey Yezerets4, Trunojoyo Anggara2, Christopher Paolucci2, Shane A. Bates1, Anuj Verma1, and Atish Parekh1
1School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907 (USA)
2Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana
3Argonne National Laboratory, Darien, IL 60439 (USA)
4Cummins Inc., Columbus, IN 47202 (USA)
Abstract — The Cu/SSZ-13 catalyst (CHA framework) is preferred for SCR applications because it shows both SCR performance and hydrothermal stability. In this work, the site requirements of the Standard SCR and NO oxidation reactions have been studied on Cu/SSZ-13. Based on an integrated experimental and modeling approach, the active site for the Standard SCR on Cu/SSZ-13 has been assigned to an isolated Cu ion located near the 6 member rings of SSZ-13, while NO oxidation required local Cu – O – Cu bonds in the 8 member cage of SSZ-13. The formation of local Cu – O – Cu bonds was a result of saturation of the number of favorable Al pairs near the 6 member ring to stabilize isolated Cu ions. The variation of the NO oxidation and the SCR rates of reaction with Cu/Al ratios was thus a catalytic consequence of different Cu ion configurations within SSZ-13. The working state of catalyst under SCR, moreover, was examined by Operando X – Ray Absorption Spectroscopy (XAS). Under reaction conditions, the Standard SCR involved a redox mechanism with both Cu(I) and Cu (II) species present. Further experiments using operando XAS to probe the redox cycle of Cu were carried out by removing the oxidizing half-reaction, which produced mostly the Cu(I) state, and then the reducing half reaction, which produced mostly the Cu(II) state. Thus, any mechanism of Standard SCR has to incorporate a redox cycle. In summary, the standard SCR on Cu-SSZ13 required isolated Cu ions to undergo a redox cycle near the 6 member ring of SSZ13.
Biography — Fabio H. Ribeiro is currently the R. Norris and Eleanor Shreve Professor of Chemical Engineering at the School of Chemical Engineering, Purdue University. He received his Ph.D. degree from Stanford University in 1989, held a post-doctoral fellowship at the University of California – Berkeley, and was on the Worcester Polytechnic Institute faculty before joining Purdue University in August 2003. His research interests consist of the kinetics of heterogeneous catalytic reactions and catalyst characterization by in situ techniques. He was Chair for AIChE’s Catalysis and Reaction Engineering Division (2010) and is editor for Journal of Catalysis.
2014 Spring Symposium
Department of Chemical and Biomolecular Engineering
University of Delaware
Newark, DE 19716
Abstract — Solar fuel production is an important technological challenge, considering that the energy of sunlight that strikes the earth’s surface in an hour is sufficient to meet our energy demands for a year. Irrespective of the approach that is pursued, oxygen evolution from water is the critical reaction, because water is the only cheap, clean and abundant source that is capable of completing the redox cycle for producing either hydrogen (from H2O) or carbonaceous fuels (from CO2) on a terawatt scale. Here, we will show our recent studies in mesoporous spinel systems, which suggest the metal sitting at the octahedral site has huge impact on the water oxidation activity of spinel catalysts. Another topic will be discussed in the presentation is the development of selective and robust CO2 reduction electrocatalyst. We will present a nanoporous Ag electrocatalyst, which is able to electrochemically reduce CO2 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.
Biography — Feng Jiao obtained his BS in chemistry at Fudan University (2001) and his PhD degree in Chemistry at University of St Andrews (Scotland, 2008), before moving to Lawrence Berkeley National Laboratory as a postdoc scholar. He spent two years in Berkeley developing solar fuel technology and joined in the Chemical and Biomolecular Engineering Department at the University of Delaware as an assistant professor in 2010. He has already published more than 35 journal papers in leading scientific journals, such as Nature Communications, J. Am. Chem. Soc., and Angew. Chem. Int. Ed. His research activities include synthesis of nanoporous materials and their potential applications in energy storage and conversion.
2014 Spring Symposium
Georgia Institute of Technology
School of Chemical & Biomolecular Engineering
Atlanta, GA 30332
Abstract — Aqueous phase processes are expected to play a key role in the production of renewable chemicals and fuels from biomass. Facile separation makes heterogeneous catalysts an attractive option for achieving high efficiency in these processes. Unfortunately, little is known about the surface chemistry of biomass-derived oxygenates in an aqueous environment. However, this knowledge will be needed to improve the activity, selectivity, and stability of catalysts for aqueous phase processes to the level we are used to in vapor phase reactions. This presentation will focus on surface interactions of biomass-derived oxygenates with metal oxides (Al2O3, TiO2, ZrO2, CeO2, MgO, Nb2O5) and supported metal catalysts (Pt/Al2O3).
The surface chemistry of aqueous solutions of polyols on polar metal oxides is strongly affected by the competition between water and the polyols for adsorption sites. Directed interactions with specific surface sites dominate. Even in the presence of water, polyols with sufficient spatial separation between their alcohol groups (e.g. glycerol) can chemisorb on Lewis acid sites forming stable multidentate surface species. The frequencies of C-O stretching vibrations of participating groups scale linearly with the electronegativity of the metal atom providing an indication for reactivity trends in acid catalyzed reactions, such as dehydration. The surface species described here can also stabilize metal oxides like γ-Al2O3 against hydrolysis in hot liquid water that would otherwise deteriorate the material. Direct dehydration of adsorbed glycerol on the Lewis acid sites of Nb2O5 yields hydroxyacetone as the main products, whereas acrolein is formed when Brønsted acid sites are involved in the conversion.
In-situ spectroscopic studies provide additional insight into the kinetics of the conversion of oxygenates in water. Specifically, ATR-IR spectroscopy is used to demonstrate that Pt/Al2O3 readily activates biomass-derived oxygenates, such as glycerol, to form surface bound CO on the Pt particles. The number of available surface sites is increased when Pt/γ-Al2O3 is cleaned by hydrogen and oxygen saturated water. After this pretreatment, some of the Pt sites that bind bridging CO show activity for the water-gas-shift reaction even at room temperature.
Biography — Carsten Sievers obtained his Diplom and Dr. rer nat. degrees in Technical Chemistry at the Technical University of Munich, Germany. Under the guidance of Prof. Johannes A. Lercher he worked on heterogeneous catalysts for various processes in petroleum refining including hydrogenation of aromatics in Diesel fuel, alkylation, alkane activation, and catalytic cracking. Additional research projects included novel catalytic system, such as supported ionic liquids. In 2007, he moved to the Georgia Institute of Technology to work with Profs. Christopher W. Jones and Pradeep K. Agrawal as a postdoctoral fellow. His primary focus was the development of catalytic processes for biomass depolymerization and synthesis of biofuels. He joined the faculty at the Georgia Institute of Technology in 2009. His research group is developing catalytic processes for the sustainable production of fuels and chemicals. Specific foci are on the stability and reactivity of solid catalysts in aqueous phase, surface chemistry of oxygenates in water, applied spectroscopy, physicochemical characterization of solid materials, synthesis of well-defined catalysts, methane conversion, pyrolysis, and gasification. He is President of the Southeastern Catalysis Society and Program Chair of the ACS Division of Catalysis Science & Technology.