Morphological Instability in Topologically Complex, Three-Dimensional Electrocatalytic Nanostructures

Meeting Program – March 2018

Yawei Li – Student Speaker

Advisor: Joshua Snyder
Department of Chemical and Biological Engineering
Drexel University, Philadelphia, Pennsylvania 19104

Abstract – Dealloying has shown increasing utility in the field of electrocatalysis as a tool for the synthesis and development of nanoporous materials possessing high surface-to-volume ratios with controlled morphology and compositional gradient (core-shell structure). After electrochemical dealloying, the open, bicontinuous, three-dimensional nanoporous nanoparticle electrocatalysts exhibit dramatically enhanced electrocatalytic properties.

In the development of efficient electrocatalysts for oxygen reduction reaction (ORR), durability is too often ignored in the pursuit of higher activities. For 3-dimensional, nanoporous materials, in addition to the standard mechanisms of electrocatalyst degradation including Pt dissolution/Ostwald ripening and coalescence/aggregation, new modes of morphological and compositional evolution must be considered. Here we use a combination of in-situ and ex-situ experimental techniques to develop insight into the structural and compositional evolution of nanoporous PtNi nanoparticles (np-NiPt) formed through the dealloying of Pt 20 Ni 80 precursor nanoparticles. We demonstrate that surface-diffusion facilitated coarsening, driven by the tendency to reduce the overall surface free energy of the system, is the dominant mechanism of electrochemical active surface area (ECSA) loss, consequently resulting in a decrease in activity.

With a better understanding of the interplay between nanoporous structure coarsening and transition metal loss, we have developed strategy to mitigate coarsening and improve operational catalyst stability by impeding step edge movement through the use of foreign adsorbates on the
surface. We show that partial monolayer decoration of np-NiPt with Ir, possessing a significantly lower rate of surface diffusion than Pt, acts to pin step edges and results in significant enhancement in catalyst durability as measured by ECSA and ORR activity retention. With this strategy we will show how more detailed insight into the atomic processes that govern electrocatalytic material instability can begin to break the inverse correlation between activity and durability.

Synthesis of Nanosized Zeolites For Different Catalytic Applications

Meeting Program – March 2018

Manuel Moliner
Manuel Moliner
Tenured Scientist, Instituto de Tecnología Química (UPV-CSIC)
Universidad Politécnica de Valencia,
Consejo Superior de Investigaciones Científicas


Abstract – On the one hand, the preparation of different zeolites, i.e. Beta and ZSM-5, in their nanosized forms with controlled Si/Al molar ratios (~15-30), high solid yields (above 90%), and homogeneous crystal sizes (~10-25 nm), has been achieved by using simple bifunctional alkyl-substituted mono-cationic cyclic ammonium cations as OSDA molecules [1]. These OSDAs combine a cyclic part and a short alkyl-chain group (preferentially C4) and, depending on the size and nature of the cyclic fragment, the crystallization of different zeolites can be controlled. The catalytic properties of the achieved nanosized zeolitic materials have been evaluated for the methanol-to-olefins and olefin oligomerization reactions [1].
On the other hand, the efficient synthesis of the small-pore CHA and AEI zeolites with nanosized crystals (20—50 nm) has also been obtained following zeolite-to-zeolite transformation procedures, where high-silica FAU materials have been used as silicon and aluminum precursors [2]. The nanosized small pore zeolites have been evaluated for the methanol-to-olefin reaction, observing that their catalyst lifetimes are remarkably longer than the catalyst lifetimes observed for conventional small pore zeolites. In addition, the selectivity towards different light olefins, i.e. propylene and/or ethylene, can be maximized depending on the crystalline structure of the nanosized zeolites.


  1. (a) E.M. Gallego et al., Chem. Sci., 2017, 8, 8138.; (b) M.R. Díaz-Rey et al., ACS Catal., 2017, 7, 6170.
  2. N. Martín et al., Chem. Commun., 2016, 52, 6072.

Biography – Manuel Moliner obtained his B.S. degree in Chemical Engineering at the University of Valencia (Spain) in 2003, and completed his Ph.D. at the Polytechnic University of Valencia (UPV, Spain), in Chemistry, under the guidance of Prof. Avelino Corma in 2008. Afterward, he completed a two-year postdoc (2008-2010) with Prof. Mark Davis at the California Institute of Technology (Caltech, USA).
He is a Tenured Scientist of the Spanish National Research Council (CSIC) since 2014, where his research lies at the interface of heterogeneous catalysis and materials design.
Manuel Moliner has published 70 papers in international journals, and is co-inventor of 24 international patents (14 transferred to industry). He has received different national and international awards, as the “EFCATS Thesis Award” to the best Ph.D. Thesis in Europe in 2007-2009, the “TR-35 Spain 2011” awarded by MIT to young talents in Spain under-35, or the “FISOCAT 2014” to young scientists under 40 in Latin America.

Remembering Robert K. Grasselli: Reflections on Three Decades of Collaboration on Complex Oxides for Selective Oxidation

Meeting Program – February 2018

Doug Buttrey
Douglas J. Buttrey
Professor of Chemical and Biomolecular Engineering,
University of Delaware


Robert GrasselliAbstract – In this presentation, I will pay tribute to the late Robert K. Grasselli, a truly extraordinary scientist who served as a dedicated mentor to many industrial scientists and engineers, as well as a number of academics, such as myself. The primary focus of his research was on improving generations of complex oxide catalysts for production of acrylonitrile by ammoxidation of propylene through much of his career, and of propane in the later years. The Sohio chemical catalysis group, which Grasselli lead for many years, succeeded in developing and steadily improving the revolutionary SOHIO process for using multicomponent bismuth molybdates to produce a 50-fold increase in production of acrylonitrile, a platform chemical used for making synthetic fibers and ABS plastics. He became Senior Science Fellow at the Sohio Company in Cleveland, and ended his career there in 1985 after about 25 years of service. This was followed by 3 years as Director of the Chemistry Division at the Office of Naval Research. From there, he moved to Mobil Research and Development Corporation in Princeton, where he worked until 1995.

Robert Grasselli was inducted into the US National Academy of Engineering in 1995. In 1996, the Sohio acrylonitrile process was recognized as the 11th National Historic Chemical Landmark by the ACS. For this work, Grasselli was admitted to the US Engineering and Science Hall of Fame.

Also in 1996, Grasselli became an adjunct professor in the Center for Catalytic Science and Technology at the University of Delaware; simultaneously, he was appointed as Guest Professor of Physical and Catalytic Chemistry at the University of Munich. He developed a number of collaborations throughout the world with William A. Goddard (CalTech), Sir John Meurig Thomas (Cambridge), Arne Andersson (Lund), Johannes Lercher (Vienna and Trieste), Ferruccio Trifiro (Bologne) and many others, including myself. I will discuss our collaborative work starting with the bismuth molybdates beginning in 1984 and, from 2002 onward, on the Mo-V-Nb-Te-O bronze “M1” catalyst for ammoxidation of propane to acrylonitrile.

Biography – Douglas J. Buttrey is a professor of Chemical and Biomolecular Engineering in the Center for Catalytic Science and Technology, with an affiliated appointment in Materials Science and Engineering, at the University of Delaware. He received his PhD degree from the Purdue University in 1984, and subsequently held the Sohio Postdoctoral Research Fellowship in the Department of Physical Chemistry at Cambridge University in 1984-85. He was a visiting assistant professor at Purdue University with a 3-way joint appointment in the Department of Chemistry, Department of Physics and Astronomy, and the School of Materials Science and Engineering from 1986-87, before moving to the University of Delaware. He is the co-author of 100 journal publications with over 5,700 citations.

Improved methane reforming activity and coking resistance of self-regenerating Ni catalyst by Atomic Layer Deposition

Meeting Program – February 2018

Chao Lin – Student Speaker

Advisor: Raymond J. Gorte
Department of Chemical and Biomolecular Engineering
University of Pennsylvania

Abstract – Perovskite-supported Ni catalysts were prepared by Atomic Layer Deposition for use in CO2 and steam reforming of methane. Thin films of CaTiO3 were grown on MgAl2O4 and used as the support. These catalysts were found to be self-regenerating following redox cycling. Activities for the ALD-prepared catalysts were higher than that observed on Ni/MgAl2O4 in both steam reforming and dry reforming. More importantly, the perovskite-supported catalysts showed minimal coking, even upon exposure to dry methane at high temperatures.

Siliceous Zeolite-supported Palladium Catalysts for Methane Oxidation

Meeting Program – January 2018

Jing Lu
Jing Lu
Staff Scientist at Clean Air Division
Johnson Matthey Inc.


Abstract – Catalytic oxidation of methane in the presence of excess of oxygen is of great interest as a practical technology to reduce methane emissions from compressed natural gas vehicles, engines, and turbines. Typical commercial methane oxidation catalysts are alumina-supported palladium catalysts. When operated at low temperatures, these catalysts exhibit rapid deactivations on stream due to water inhibition. In addition, these Pd-catalysts are sensitive to sulfur poisoning, even with the presence of a trace amount (≤ 1 ppm) of SO2 in the feed. Among other oxide materials, zeolites were also investigated as a potential support for palladium – such as the effects of frameworks and exchange or impregnation methods – but no significant benefits were discovered in the past comparing to conventional alumina-based catalysts. Here, we demonstrate the application of siliceous zeolites (i.e. SiO2-to-Al2O3 ratio (SAR) >1200) as Pd-support, the resulting catalysts exhibit significantly improved activity and on-stream durability at low temperatures, and are able to be regenerated from sulfur poisoning under realistic operating conditions.

Biography – Jing Lu received his B.S. degree in Chemical Engineering from University of California, Santa Barbara. He joined Johnson Matthey in 2013 after earning a Ph.D. from University of California, Davis where he worked with Prof. Bruce Gates. Jing is currently a Staff Scientist leading the developments of selective catalytic reduction, ammonia slip control and methane oxidation catalysts for diesel and natural gas aftertreatment. He is an inventor of several patents and author of 19 journal articles.

Kinetic Peculiarities of Cu-Zeolite SCR Catalysts, and Their Practical Implications

Meeting Program – November 2017

Aleksey Yezerets
Aleksey Yezerets
Director of Advanced Chemical Systems & Integration
Cummins Inc.


Abstract – Cu-Zeolite SCR catalysts have emerged in the recent years as the leading technology for meeting the challenge of NOx reduction in diesel exhaust. Despite their excellent performance and stability characteristics, integrating this class of catalysts into an effective and durable exhaust aftertreatment system has proved non-trivial. Such systems must be capable of operating over a broad range of transient conditions, survive a variety of nominal and off-nominal aging exposures, and sustain their activity over many years of active duty. This requires a detailed understanding of the reaction mechanism and deactivation pathways, and the ability to translate those into reaction engineering guidance to system design, feedback control algorithms, and on-board diagnostics. In this presentation, we will share examples from our recent findings related to the controlling regimes of operation and to the deactivation mechanisms of Cu-Zeolite catalysts – at the level of catalyst material, chemical functions, and overall emission reduction performance in the context of a system which contains multiple catalytic elements. We will further discuss the advancements in the ability to model the behaviors of healthy and deactivated catalysts, and the respective implications to system optimization and control.

Biography – As Director of Advanced Chemical Systems & Integration with Corporate R&T Division of Cummins Inc., the world’s largest independent manufacturer of diesel engines and related equipment, Dr. Aleksey (Alex) Yezerets leads a team of experimentalists and modelers responsible for developing an understanding of the performance and deactivation of batteries, catalysts, and sensors, and for providing guidance and support to electrified and low-emission products at all stages of their lifecycles. He also coordinates a portfolio of collaborative research programs with industrial partners, National Labs, and universities. He has authored or co-authored 35 patents and 80 peer-reviewed publications, with over 2500 total citations. Alex maintains currency in his field by an active engagement in professional, editorial, and graduate education activities. His technical contributions have been recognized by awards from the Catalysis Club of Chicago, R&D100, ACS, AIChE and SAE, as well as by two Cummins Julius Perr awards for innovation. Alex has been elected an SAE Fellow.

Olefin Metathesis by Supported MoOx/Al2O3 Catalysts

Meeting Program – October 2017

Anisha Chakrabarti – Student Speaker

Advisor: Israel E. Wachs
Operando Molecular Spectroscopy & Catalysis Laboratory
Department of Chemical and Biomolecular Engineering
Lehigh University, Bethlehem, PA 18015 USA

Abstract – The olefin metathesis reaction was commercialized in the late 1960s to produce ethylene and 2-butene from propylene in the Phillips Triolefin Process. The reverse reaction, however, is currently desired due to a global propylene shortage caused by the shift to lighter feedstocks derived from shale gas fracking. Heterogeneous supported MoOx/Al2O3 catalysts are employed for olefin metathesis in the Shell Higher Olefin Process (SHOP) that operates between room temperature and ~200°C.

To probe the molecular details of the supported MoOx/Al2O3 catalysts, a modern in situ spectroscopy approach was undertaken. In situ UV-vis measurements (Eg values) confirmed the presence of isolated and oligomeric MoOx surface sites, with the latter increasing with molybdena loading. In situ Raman spectroscopy revealed that at low loadings of molybdena (<1 Mo atoms/nm2), only isolated dioxo (O=)2MoO2 surface sites are present. As the molybdena loading is increased (1-4.6 Mo atoms/nm2), oligomeric mono-oxo O=MoO4 surface sites co-exist with the isolated dioxo (O=)2MoO2 surface sites. Above monolayer loadings (>4.6 Mo atoms/nm2), crystalline MoO3 nanoparticles are also present. In situ IR indicates that the isolated dioxo MoO4 sites are anchored at more basic HO-μ1-AlIV surface hydroxyls, while the surface oligomeric mono-oxo sites are anchored to more acidic HO-μ1/3-AlV/VI surface hydroxyls. Propylene metathesis at reaction conditions suggest that the isolated dioxo (O=)2MoO2 surface site may still be present after activation of the mono-oxo surface sites with propylene. In situ UV-vis during propylene metathesis indicates that Mo+6 sites are dominant during propylene metathesis due to the presence of unreduced surface dioxo Mo+6O4 sites and re-oxidation of reduced Mo+4 sites by propylene back to Mo+6=CH2 and Mo+6=CHCH3 reaction intermediates. The surface chemistry was chemically probed by C3H6-TPSR that initially formed oxygenated products (CH3CHO, H2CO, CH3COCH3, H2O and CO/CO2) during catalyst activation. The reactivity of the activated catalysts to butene progressively increased with molybdena loading, indicating that the oligomeric mono-oxo MoOx sites are much more active than isolated dioxo MoO4 sites for olefin metathesis. The crystalline MoO3 nanoparticles, however, were found to be inactive for metathesis. This presentation will address the fundamental molecular and structural details of the supported MoOx/Al2O3 catalysts during propylene metathesis and establish their structure-activity relationships.