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.

Converting CO2 via Thermocatalysis and Electrocatalysis

Meeting Program – October 2017

Jingguang Chen
Jingguang Chen
Thayer Lindsley Professor of Chemical Engineering
Columbia University

 

Abstract – Rising atmospheric concentration of CO2 is forecasted to have potentially disastrous effects on the enviroment from its role in global warming and ocean acidification. Converting CO2 into valuable chemicals and fuels is one of the most practical routes for reducing CO2 emissions while fossil fuels continue to dominate the energy sector. The catalytic reduction of CO2 by H2 can lead to the formation of three types of products: CO through the reverse water-gas shift (RWGS) reaction, methanol via selective hydrogenation, and methane by the methanation pathway. In the current talk we will first describe our efforts in controlling the catalytic selectivity for the three products using a combination of DFT calculations and surface science studies over single crystal surfaces, catalytic evaluation of supported catalysts, and in-situ characterization under reaction conditions. Next, we will discuss our efforts in converting CO2 without using H2. This is motivated by the fact that ~95% of H2 is generated from hydrocarbon-based feedstocks, producing CO2 as a byproduct. We will present two approaches to avoid using H2 for CO2 conversion. The first approach involves the utilization of light alkanes, such as ethane, to directly reduce CO2 via the dry reforming pathway to produce synthesis gas (C2H6 + 2CO2 → 4CO + 3H2) and the oxidative dehydrogenation route to generate ethylene (C2H6 + CO2 → C2H4 + CO + H2O). The second approach is the electrolysis of CO2 to produce synthesis gas with controlled CO/H2 ratios. We will conclude our presentation by providing a perspective on the challenges and opportunities in converting CO2 via various routes in thermocatalysis and electrocatalysis.

Biography – Jingguang Chen is the Thayer Lindsley Professor of chemical engineering at Columbia University, with a joint appointment as a senior chemist at Brookhaven National Laboratory. He received his PhD degree from the University of Pittsburgh and then carried out his Humboldt postdoctoral research in KFA-Julich in Germany. After spending several years as a staff scientist at Exxon Corporate Research, he started his academic career at the University of Delaware in 1998 and rose to the rank of the Claire LeClaire Professor of chemical engineering and the director of the Center for Catalytic Science and Technology. He moved to Columbia University in 2012. He is the co-author of 21 US patents and over 340 journal publications with over 15,000 citations. He is currently the president of the North American Catalysis Society (NACS) and an associate editor of ACS Catalysis. He received many catalysis awards, including the 2015 George Olah award from ACS and the 2017 Robert Burwell Lectureship from NACS.

Structure Activity Relationships in Homogeneous Catalysis

Meeting Program – September 2017

Thomas Colacot
Thomas Colacot
Technical Fellow & Global R & D Manager
Johnson Matthey

 

Abstract – Homogeneous catalysis is a molecular phenomenon, where the structure of the catalyst plays a significant role on the activity and selectivity of a catalytic reaction. Three cases studies will be discussed during the talk to explain the phenomena. The topics are

  1. High purity palladium acetate vs commercial in organic synthesis
  2. Ir pre catalysts for C-H activated borylation
  3. Generation of L1Pd(0) catalysts for advanced cross coupling.

References:

  • Book: New Trends in Cross Coupling: Theory and Applications, ed. Thomas J. Colacot, Royal Society of Chemistry, Cambridge, UK, 2015. ISBN: 978-1-84973-896-5
  • Carin C. C. Johansson Seechurn, Thomas Sperger, Theresa. G. Scrase, Franziska. Schoenebeck and Thomas. J. Colacot*, J. Am. Chem. Soc., 2017 (DOI: 10.1021/jacs.7b01110). This work was featured in the April 5 th issue of C & EN. Please see: http://acsmeetings.cenmag.org/chemists-get-better-acquainted-with-palladium-catalysts/
  • William A. Carole and Thomas J. Colacot* Chem. Eur. J, 2016, 22, 7686 (with journal cover graphics – this work was featured in C & EN. page 20, May 2 nd, 2016)
  • Peter G. Gildner, Andrew DeAngelis, and Thomas J. Colacot*, Org. Lett., 2016, 18 (6), 1442–1445 DOI: 10.1021/acs.orglett.6b0037
  • William A. Carole, Jonathan Bradley, Misbah Sarwar and Thomas J. Colacot* Org. Lett., 2015, 17 (21), 5472–5475. DOI: 10.1021/acs.orglett. 5b02835
  • Thomas. J. Colacot, Angew Chem. Int. Ed. 2016, 54, 15611-15612.
  • Peter G. Gildner and Thomas J. Colacot* Organometallics, 2015, 34 (23), 5497–5508. DOI: 10.1021/acs.organomet.5b00567
  • Andrew J. DeAngelis , Peter G. Gildner , Ruishan Chow , and Thomas J. Colacot* J. Org. Chem., 2015, 80 (13), pp 6794–6813, DOI: 10.1021/acs.joc.5b01005
  • Carin C. C. Johansson Seechurn, Vilvanathan Sivakumar, Deepak Satoskar and Thomas J. Colacot*, Organometallics, 2014, 33, 3514−3522.

Biography – Dr. Thomas J. Colacot received his Ph.D. in Chemistry from IIT Madras in 1989, following a B.Sc. and M.Sc. in Chemistry from the University of Kerala in 1981 and 1983, respectively. After his doctoral and post-doctoral studies in the US, Dr. Colacot went on to pursue an education in management, acquiring an MBA from Pennsylvania State University in 2005, while working at Johnson Matthey. Before joining Johnson Matthey in 1995, Dr. Colacot had also worked as a Research Associate Southern Methodist University (TX, USA) on a project funded by Advanced Technology Program, as an Assistant Professor at Florida A&M University, and as a Post-Doctoral/Teaching Fellow at University of Alabama. Having climbed up the ranks from Development Associate (bench chemist), Dr. Colacot is currently the Technical Fellow at Johnson Matthey, USA, the highest technical rank for a scientist with reports from different parts of the world.

As a researcher, Dr. Colacot has focused on many areas of homogenous catalysis, particularly becoming proficient in palladium-catalyzed cross-coupling. He also has extensive experience in organometallic and organic syntheses, and in process chemistry. His work is reflected in several patents to his name, more than one hundred peer-reviewed publications, and numerous invited lectures and seminars spanning India, USA, China, and Europe. His recently edited book: New Trends in Cross Coupling: Theory and Applications by the Royal Society of Chemistry is widely used in academia and industry. Through his work, Dr. Colacot is credited with being a leading influence in developing exceptional catalytic systems for the advancement of metal-catalyzed synthetic organic chemistry for real world applications such as drug development, OLED’s/liquid crystals and agriculture. His emphasis in designing catalysts and catalytic processes has been on their applicability in industrial settings, particularly pertaining to agriculture, electronics and medicine. He is the finest example of a link between academia and industry.

Dr. Colacot’s contributions to the field have resulted in many awards and accolades, amongst them the recent prestigious IIT Madras 2016 Distinguished Alumnus Award for Technology Innovations and Chemical Research Society of India (2016 CRSI) Medal for outstanding contributions in Organometallics and Homogeneous Catalysis. He is the first Indian to be awarded the American Chemical Society (ACS) National Award in Industrial Chemistry in 2015. He also received the 2015 IPMI Henry Alfred Award (2015) from the International Precious Metal Institute, sponsored by the BASF. In 2014 he received the Indian American Kerala Culture and Civic Center Award for his outstanding contributions in Applied Sciences. In addition, he received Royal Society of Chemistry 2012 Applied Catalysis Award and Medal. He is also a Fellow of the Royal Society of Chemistry, UK.

Production of para-methylstyrene and para-divinylbenzene from furanic compounds

2017 Spring Symposium

Molly Koehle and Raul Lobo, Chemical and Biomolecular Engineering, University of Delaware, Newark, DE

Abstract – Of the three isomers of methylstyrene, para-methylstyrene is highly desirable because it yields polymers with superior properties over polystyrene and mixed poly-methylstyrene [1]. However, controlling the substitution of methylstyrene via direct acylation or alkylation of toluene is difficult because even though the para isomer is favored, meta and ortho isomers are also formed [1, 2], and separation of the isomer mixture is very difficult due to their nearly identical properties.

The Diels-Alder cycloaddition and dehydration of substituted furans with ethylene is a plausible route to p-methylstyrene since it is inherently selective to para aromatic species. We have successfully developed a three-step catalytic route to p-methylstyrene from methylfuran (Scheme 1) at high yield and very high isomer selectivity. The process uses Friedel-Crafts acylation, selective reductions with hydrogen and Diels-Alder cycloaddition with ethylene. The raw materials—furans, ethylene and acetic acid—can all be derived from biomass [3,4], thus allowing ‘green’ styrene production from renewable carbon sources. This approach has also been extended to the production of p-divinylbenzene. As the acylation step is known to be catalyzed by Lewis acids, recent work has focused on studying this step on Brønsted and Lewis acid zeolites and will be presented as well.

Scheme 1: Production of para-methylstyrene from methylfuran

References:
[1] W.W. Kaeding and G.C. Barile, in: B.M. Culbertson and C.U. Pittman, Jr. (Eds.), New Monomers and Polymers, Plenum Press, New York, NY, 1984, pp. 223-241.
[2]“Aromatic Substitution Reactions.” http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/benzrx1.htm
[3] A.A. Rosatella; S.P. Simeonov; R.F.M. Frade, R.F.M..; C.A.M. Afonso, Green Chem., 13 (2011) 754.
[4] C.H. Christensen; J. Rass-Hansen; C.C. Marsden; E. Taarning; K. Egeblad, ChemSusChem, 1 (2008) 283.

Biography – Molly obtained her B.S. in Chemical Engineering from the University of Pittsburgh and her M.S. in Chemical Engineering from the University of Connecticut. She has worked at the Catalysis Center for Energy Innovation in Prof. Raul Lobo’s group since 2013. Her work focuses on transformations of biomass to fuels and chemicals with Bronsted and Lewis acid zeolites.

The mechanism of CO2 reduction over Pd/Al2O3: a combined steady state isotope transient kinetic analysis (SSITKA) and operando FTIR investigation

2017 Spring Symposium

Xiang Wang, Hui Shi and János Szanyi, Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, WA

Abstract – Understanding the critical steps involved in the heterogeneous catalytic CO2 reduction has attracted a lot of attention recently. In order to fully understand the mechanism of this reaction the determination of both the rate-determining steps and reaction intermediates are vital. Steady-State Isotopic Transient Kinetic Analysis (SSITKA) is one of the most powerful techniques used to investigate the elementary steps under steady-state reaction conditions. This technique provides valuable information on mean resident lifetime of surface intermediates, surface concentrations of adsorbed reactant species and an upper bound of the turnover frequency. Coupling SSITKA with operando-FTIR spectroscopy allows us to discriminate between active and spectator species present on the catalytic surface under steady state reaction conditions.  In the present work operando SSITKA experiments coupled with transmission FTIR, mass spectrometry (MS) and gas chromatography (GC) were performed to probe both the chemical nature and kinetics of reactive intermediates over a Pd-Al2O3 catalysts and provide a clear mechanistic picture of the CO2 hydrogenation reaction by revealing the rate-determining steps for CH4 and CO production.

Figure 1 shows normalized real-time signals for the decay and increase of methane (a) and carbon-monoxide (b) in the effluent at 533 K reaction temperature after the feed gas was switched at 0 s from CO2/H2/Ar mixture to 13CO2/H2 mixture.  With increasing temperature, the decay of CH4 and CO get faster.  By integration under the decay curves , the mean surface-residence times CH4 and  CO), the abundance of adsorbed surface intermediates leading to CH4 and CO products  CH4 and  CO) at 533-573 K were calculated. At low temperature, CO2 methanation is slower than the reverse water-gas shift reaction, but became faster as the temperature was increased over 563 K.  The similar apparent activation energies obtained for the hydrogenation of adsorbed CO and for the formation of CH4 indicates that the hydrogenation of CO is the rate-determining step during the CO2 methanation reaction. Moreover, the similar apparent activation energies estimated for the consumption of adsorbed formates (FTIR) and for the formation of CO (MS), indicates that the H-assisted decomposition of formates is the rate determining step in the reverse water gas shift reaction.  The rate-determining step for CO formation is the conversion of adsorbed formate, while that for CH4 formation is the hydrogenation of adsorbed carbonyl. The balance of the hydrogenation kinetics between adsorbed formates and carbonyls governs the selectivities to CH4 and CO. We applied this knowledge to design catalysts and achieved high selectivities to desired products. 


Figure 1. Normalized response of (a) CH4 and 13CH4 products and (b) CO and 13CO products as functions of time.

Biography – Dr. Szanyi`s research is focused on surface science, spectroscopy and kinetic studies on heterogeneous catalytic reaction systems aimed at understanding structure-reactivity relationships. In particular, he is interested in understanding the mechanistic consequences of very high (atomic) metal dispersion on different support materials. Using a series of ensemble averaged spectroscopy methods he investigates the fundamental properties of metal atoms and small metal clusters prepared under well controlled UHV conditions. These results provide information on the energetics of the interactions between highly dispersed metals and selected probe molecules. Applying in situ RAIR spectroscopy they study the binding configurations of adsorbates to metals, and identify surface species present on the metal and support materials under elevated reactant pressures. Simultaneously, they are conducting detailed kinetics and operando spectroscopy measurements on model high surface area supported metal catalysts using flow reactors and SSITKA/FTIR/MS techniques. These measurements provide detailed kinetic information together with surface speciation that allow them to greatly enhance our mechanistic understanding of heterogeneous catalytic systems, in particular the reduction of CO2. Dr Szanyi is also involved in research related to the fundamental understanding of automotive emission control catalysis, conducting research in selective catalytic reduction of NOx on zeolite-based catalysts, low temperature NO and CO oxidation on metal oxides, and low temperatures NOx and HC storage in zeolites.

Design of complex metal/metal-oxide heterogeneous catalytic materials for energy and chemical conversion

2017 Spring Symposium

Eranda Nikolla, Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, MI

Abstract – Dwindling fuel resources and high levels of CO2 emissions have increased the need for renewable energy resources and more efficient energy conversion and storage systems. In this talk, some of our recent work on designing efficient (active, selective and stable) catalytic systems for energy and chemical conversions will be discussed. First, I will talk about our work on designing layered nickelate oxide electrocatalysts for electrochemical oxygen reduction and evolution reactions. These processes play an important role in fuel cells, electrolyzers and Li-air batteries. We have utilized density functional theory (DFT) calculations to identify the factors that govern the activity of nickelate oxides toward these processes. Using a reverse microemulsion approach we demonstrate an approach for synthesizing nanostructured nickelate oxide electrocatalysts with controlled surface structure. These nanostructures are thoroughly characterized using atomic-resolution high angle annular dark field (HAADF) imaging along with electron energy-loss spectroscopy (EELS) performed using an aberration corrected scanning transmission electron microscope (STEM). Controlled kinetic isotopic and electrochemical studies are used to develop structure/performance relationships to identify nickelate oxides with optimal electrocatalytic activity. Secondly, I will discuss our efforts on designing efficient catalytic systems for biomass conversion processes. Development of active and selective catalysts for biomass conversion is critical in realizing a renewable platform for fuels and chemicals. I will highlight some of our recent work on utilizing reducible metal oxide encapsulated noble metal catalytic materials to promote hydrodeoxygenation (HDO) of biomass-derived compounds. We show enhancement in HDO activity and selectivity due to the encapsulation of the metal nanoparticles by an oxide film providing high interfacial contact between the metal and metal oxide sites, and restrictive accessible conformations of aromatics on the metal surface.

Biography – Eranda Nikolla is an assistant professor in the Department of Chemical Engineering and Materials Science at Wayne State University since Fall 2011. Her research interests lie in the development of heterogeneous catalysts and electrocatalysts for chemical conversion processes and electrochemical systems (i.e., fuel cells, electrolyzers) using a combination of experimental and theoretical techniques. Dr. Nikolla received her Ph.D. in Chemical Engineering from University of Michigan in 2009 working with Prof. Suljo Linic and Prof. Johannes Schwank in the area of solid-state electrocatalysis. She conducted a two-year postdoctoral work at California Institute of Technology with Prof. Mark E. Davis prior to joining Wayne State University. At Caltech she developed expertise in synthesis and characterization of meso/microporous materials and functionalized surfaces. Dr. Nikolla is the recipient of a number of awards including the National Science Foundation CAREER Award, the Department of Energy CAREER Award, 2016 Camille Dreyfus Teacher-Scholar Award and the Young Scientist Award from the International Congress on Catalysis.