Catalysis

Department of Chemical and Petroleum Engineering, University of Pittsburgh
Ph.D., Theoretical and Computational Chemistry, University of Crete, 2006
Summary:

My research expertise is interdisciplinary, blending concepts and techniques from Chemistry, Physics, Materials Science and Chemical Engineering. I use theory and computation to investigate the physicochemical properties of nanomaterials with potential applications in diverse nanotechnological areas, ranging from energy generation and storage, to materials design, nanoparticle growth, magnetism, and catalysis.

In the Computer-Aided Nano and Energy Lab (C.A.N.E.LA.), led by Prof. Mpourmpakis, we use theory and computation to investigate the physicochemical properties of nanomaterials with potential applications in diverse nanotechnological areas, ranging from green energy generation and storage to materials engineering and catalysis. Our laboratory core expertise lies on "ab-initio" electronic-structure theoretical calculations. We develop structure-activity relationships and apply multiscale tools to elucidate complex chemical processes that take place on nanomaterials. Ultimately, we design novel nanostructures with increased, molecular-level precision and tailored multifunctionality. 

Most Cited Publications: 
  1. "SiC Nanotubes:  A Novel Material for Hydrogen Storage," Giannis Mpourmpakis and George E. Froudakis, George P. Lithoxoos and Jannis Samios, Nano Lett. 6, 1581 (2006)
  2. "Carbon Nanoscrolls:  A Promising Material for Hydrogen Storage," Giannis Mpourmpakis, Emmanuel Tylianakis, and George E. Froudakis, Nano Lett. 7, 1893 (2007)
  3. "Correlating Particle Size and Shape of Supported Ru/γ-Al2O3 Catalysts with NH3 Decomposition Activity," Ayman M. Karim, Vinay Prasad, Giannis Mpourmpakis, William W. Lonergan, Anatoly I. Frenkel, Jingguang G. Chen and Dionisios G. Vlachos, J. Am. Chem. Soc.131, 12230 (2009)
  4. "Stabilization of Si-based cage clusters and nanotubes by encapsulation of transition metal atoms," Antonis N Andriotis, Giannis Mpourmpakis, George E Froudakis2 and Madhu Menon, New J. Phys. 4, 78 (2002)
  5. "Why boron nitride nanotubes are preferable to carbon nanotubes for hydrogen storage?: An ab initio theoretical study," Giannis Mpourmpakis, George E. Froudakis, Catalysis Today 120, 341 (2007)
Recent Publications: 
  1. "CO2 activation on bimetallic CuNi nanoparticles," Natalie Austin, Brandon Butina, Giannis MpourmpakisProgress in Natural Science: Materials International 26, 487 (2016)
  2. "From Biomass-Derived Furans to Aromatics with Ethanol over Zeolite," Ivo F. Teixeira, Benedict T. W. Lo, Pavlo Kostetskyy, Michail Stamatakis, Lin Ye, Chiu C. Tang, Giannis Mpourmpakis, Shik Chi Edman Tsang, Angew. Chem. Int. Ed. 55, 13061 (2016)
  3. "Molecular modifiers reveal a mechanism of pathological crystal growth inhibition," Jihae Chung, Ignacio Granja, Michael G. Taylor, Giannis Mpourmpakis, John R. Asplin & Jeffrey D. Rimer, Nature 536, 446 (2016)
  4. "Description and Role of Bimetallic Prenucleation Species in the Formation of Small Nanoparticle Alloys," Lauren E. Marbella, Daniel M. Chevrier, Peter D. Tancini, Olabobola Shobayo, Ashley M. Smith, Kathryn A. Johnston, Christopher M. Andolina, Peng Zhang, Giannis Mpourmpakis, and Jill E. Millstone, J. Am. Chem. Soc. 137, 15852 (2015)
  5. "Catalyst Design Based on Morphology- and Environment-Dependent Adsorption on Metal Nanoparticles," Michael G. Taylor, Natalie Austin, Chrysanthos E. Gounaris, and Giannis MpourmpakisACS Catal. 5, 6296 (2015)

Oxide-metal Interfaces as Active Sites for Acid-base Catalysis: Oxidation State of Nanocatalyst Change with Decreasing Size, Conversion of Heterogeneous to Homogeneous Catalysis, Hybrid Systems

Speaker(s): 
Gábor A. Somorjai
Dates: 
Friday, May 6, 2016 -
9:30am to 10:30am

When metal nanoparticles are placed on different mezoporous or microporous oxide supports the catalytic turnover rates and selectivities markedly change.  The charge flow between the metal and the oxide ionizes the adsorbed molecules at the oxide-metal interfaces and alters the catalytic chemistry (acid-base catalysis). 

The oxidation state of metal nanoparticles becomes less metallic and assume higher oxidation states with decreasing size.  The...

Metal Nanocatalysts, Their Synthesis and Size Dependent Covalent Bond Catalysis: Instrumentation for Characterization under Reaction Conditions

Speaker(s): 
Gábor A. Somorjai
Dates: 
Thursday, May 5, 2016 -
5:00pm to 7:00pm

Colloidal chemistry is used to control the size, shape and composition of metal nanoparticles usually in the 1-10 nm range.  In-situ methods are used to characterize the size, structure (electronic and atomic), bonding, composition and oxidation states under reaction conditions.  These methods include sum frequency generation nonlinear optical spectroscopy (SFG), ambient pressure X-ray photoelectron spectroscopy (APXPS) and high pressure scanning tunneling...

Department of Chemistry, University of Pittsburgh
Ph.D., Computational Organic Chemistry, University of California, 2010
Summary:

Reactivity and Selectivity Rules in Organic and Organometallic Reactions
We are developing computational models to quantitatively describe the origins of reactivity and selectivity in organocatalytic and transition metal-catalyzed reactions. We perform quantum mechanical calculations to explore the reaction mechanism, followed by thorough analysis on various stereoelectronic effects to predict how changes of the catalyst structure, substituents, and solvent affect rate and selectivity. We use quantitative energy decomposition methods to dissect the key interactions in the transition state and provide chemically meaningful interpretation to the computed reactivity and selectivity. We apply these computational studies to a broad range of organic and organometallic reactions, such as C–H and C–C bond activations, coupling reactions, olefin metathesis, and polymerization reactions. 

Catalyst Screening and Prediction
We are developing a multi-scale computational screening protocol which could efficiently rank the catalysts based on ligand-substrate interaction energies in the transition state. 

Applications of Computational Chemistry in Understanding Organic Chemistry
We are collaborating with experimental groups at Pitt and many other institutions to solve problems in organic chemistry using computational methods and programs. Our goal is to establish the most effective strategy to use modern computational methods and hardware to help address the grand challenges in synthetic chemistry. 

 

Most Cited Publications: 
  1. "Computational Studies of Ruthenium-Catalyzed Olefin Metathesis," Peng Liu, Buck LH Taylor, Jesus Garcia-Lopez, Kendall N Houk, Handbook of Metathesis, 2nd Edition, Volume 1: Catalyst Development and Mechanism (2015)
  2. "Computational Explorations of Mechanisms and Ligand-Directed Selectivities of Copper-Catalyzed Ullmann-Type Reactions," Gavin O. Jones, Peng Liu, K. N. Houk and Stephen L. Buchwald, J. Am. Chem. Soc. 132, 6205 (2010)
  3. "Suzuki−Miyaura Cross-Coupling of Aryl Carbamates and Sulfamates: Experimental and Computational Studies," Kyle W. Quasdorf, Aurora Antoft-Finch, Peng Liu, Amanda L. Silberstein, Anna Komaromi, Tom Blackburn, Stephen D. Ramgren, K. N. Houk, Victor Snieckus, and Neil K. Garg, J. Am. Chem. Soc. 133, 6352 (2011)
  4. "Z-Selectivity in Olefin Metathesis with Chelated Ru Catalysts: Computational Studies of Mechanism and Selectivity," Peng Liu, Xiufang Xu, Xiaofei Dong, Benjamin K. Keitz, Myles B. Herbert, Robert H. Grubbs, and K. N. Houk, J. Am. Chem. Soc. 134, 1464 (2012)
  5. "Palladium-Catalyzed Meta-Selective C–H Bond Activation with a Nitrile-Containing Template: Computational Study on Mechanism and Origins of Selectivity," Yun-Fang Yang, Gui-Juan Cheng, Peng Liu, Dasheng Leow, Tian-Yu Sun, Ping Chen, Xinhao Zhang, Jin-Quan Yu, Yun-Dong Wu, and K. N. Houk, J. Am. Chem. Soc. 136, 344 (2014)
Recent Publications: 
  1. "Benzazetidine synthesis via palladium-catalysed intramolecular C−H amination," Gang He, Gang Lu, Zhengwei Guo, Peng Liu & Gong Chen, Nature Chemistry 8, 1131 (2016)
  2. "Catalytic activation of carbon–carbon bonds in cyclopentanones," Ying Xia, Gang Lu, Peng Liu & Guangbin Dong, Nature 539, 546 (2016)
  3. "Photoredox-mediated Minisci C–H alkylation of N-heteroarenes using boronic acids and hypervalent iodine," Guo-Xing Li, Christian A. Morales-Rivera, Yaxin Wang, Fang Gao, Gang He, Peng Liu and Gong Chen, Chem. Sci. 7, 6407 (2016)
  4. "Copper-catalyzed asymmetric addition of olefin-derived nucleophiles to ketones," Yang Yang, Ian B. Perry, Gang Lu, Peng Liu, Stephen L. Buchwald, Science 353, 144 (2016)
  5. "Rhodium-Catalyzed Intramolecular [5+2] Cycloaddition of Inverted 3-Acyloxy-1,4-enyne and Alkyne: Experimental and Theoretical Studies," Xiaoxun Li, Wangze Song, Xiaona Ke, Xiufang Xu, Peng Liu, K. N. Houk, Xian-liang Zhao, Weiping Tang, Chem. Eur. J. 22, 7079 (2016)
Department of Chemical and Petroleum Engineering, University of Pittsburgh
Ph.D., Chemistry, California Institute of Technology, 2007
Summary:

The Keith group applies and develops computational chemistry to study and discover solutions to problems at the interface of engineering and basic science.  They are currently focused on modeling chemical reaction mechanisms and the atomic scale of materials to help develop renewable energy and sustainability technologies.

The group uses quantum chemistry-based multiscale modeling to predict and study the atomic scale of materials and chemical reactions. With electronic structure and atomistic methods, they can investigate fundamental reaction steps at different time- and length-scales that would otherwise be difficult or impossible to investigate with experiment. 

Notably, their studies are entirely carried out in silico (on a computer) and almost entirely free from artificial biases that are present when using experimental inputs. Whether doing so alone or in collaboration with experimentalists, the group provides deep perspective on the atomic-scale of catalytic environments to understand how they work and how to further improve them.

The 'ground-up' multiscale modeling approach uses appropriate levels of quantum chemistry (QC) theory (typically on up to ca. 200 atoms) to model reaction energiesbarrier heightspKas, and standard redox potentials. Using data obtained from QC theory, they can also develop analytic reactive forcefields, which are capable of modeling reaction dynamics on systems on the order of 100,000 atoms. Reactive forcefield data in turn can be used to generate rate constant libraries for kinetic Monte Carlo (kMC) simulations to model larger time-scale and length-scale phenomena such a nanoparticle/material growth and ripening.

Most Cited Publications: 
  1. "The Mechanism of the Wacker Reaction: A Tale of Two Hydroxypalladations," John A. Keith, Patrick M. Henry, Angew. Chem. Int. Ed. 48, 9038 (2009)
  2. "Water Oxidation on Pure and Doped Hematite (0001) Surfaces: Prediction of Co and Ni as Effective Dopants for Electrocatalysis," Peilin Liao, John A. Keith, and Emily A. Carter, J. Am. Chem. Soc. 134, 13296 (2012)
  3. "Theoretical Elucidation of the Competitive Electro-oxidation Mechanisms of Formic Acid on Pt(111)," Wang Gao, John A. Keith, Josef Anton, and Timo Jacob, J. Am. Chem. Soc. 132, 18377 (2010)
  4. "Theoretical Investigations of the Oxygen Reduction Reaction on Pt(111)," John A. Keith, Gregory Jerkiewicz, Timo Jacob, ChemPhysChem 11, 2779 (2010)
  5. "Theoretical Studies of Potential-Dependent and Competing Mechanisms of the Electrocatalytic Oxygen Reduction Reaction on Pt(111)," John A. Keith, Timo Jacob, Angew. Chem. Int. Ed. 49, 9521 (2010)
Recent Publications: 
  1. "Nitrogen-doped nanocarbon materials under electroreduction operating conditions and implications for electrocatalysis of CO2," Karthikeyan Saravanan, Eric Gottlieb, John A. KeithCarbon 111, 859 (2017)
  2. "Explicitly Unraveling the Roles of Counterions, Solvent Molecules, and Electron Correlation in Solution Phase Reaction Pathways," Mitchell C. Groenenboom and John A. KeithJ. Phys. Chem. B 120, 10797 (2016)
  3. "Structural and Substituent Group Effects on Multielectron Standard Reduction Potentials of Aromatic N-Heterocycles," Mitchell C. Groenenboom, Karthikeyan Saravanan, Yaqun Zhu, Jeffrey M. Carr, Aude Marjolin, Gabriel G. Faura, Eric C. Yu, Raymond N. Dominey, and John A. KeithJ. Phys. Chem. A 120, 6888 (2016)
  4. "Neural network and ReaxFF comparison for Au properties," Jacob R. Boes, Mitchell C. Groenenboom, John A. Keith, John R. Kitchin, International Journal of Quantum Chemistry 116, 979 (2016)
  5. "Standard redox potentials, pKas, and hydricities of inorganic complexes under electrochemical conditions and implications for CO2 reduction," K. Saravanan and J. A. KeithDalton Trans. 45, 15336 (2016)
Department of Chemical and Petroleum Engineering, University of Pittsburgh
Ph.D., Chemical Engineering, Cornell University, 1992
Summary:

The Johnson group tackles fundamental problems over a wide range of subject areas using state-of-the-art atomistic modeling methods. Current projects include CO2 capture through the following methods:

  • Selective adsorption in metal organic frameworks (MOFs).
  • Catalytic nanoparticles on amorphous supports.
  • Multiscale modeling proton-exchange membrane (PEM) based fuel cells.  
  • Hydrogen storage in metal hydrides.
  • Absorption into ionic liquids, including ionic liquids that react chemically with CO2.
  • Physical absorption of CO2 into liquid sorbents.
  • Chemical capture involving carbamate forming amines.
  • Solid-state reactions involving carbonates and bicarbonates.

Tools we use in our studies include Kohn-Sham density functional theory, first principles quantum mechanics methods, classical equilibrium and non-equilibrium molecular dynamics, and Monte Carlo simulation techniques.

Most Cited Publications: 
  1. "The Lennard-Jones equation of state revisited," J. Karl Johnson, John A. Zollweg & Keith E. Gubbins, Molecular Physics 78, 591 (1993)
  2. "Microporous Metal Organic Materials:  Promising Candidates as Sorbents for Hydrogen Storage," Long Pan, Michelle B. Sander, Xiaoying Huang, Jing Li, Milton Smith, Edward Bittner, Bradley Bockrath, and J. Karl JohnsonJ. Am. Chem. Soc. 126, 1308 (2004)
  3. "Molecular simulation of hydrogen adsorption in single-walled carbon nanotubes and idealized carbon slit pores," Qinyu Wang and J. Karl JohnsonJ. Chem. Phys. 110, 577 (1999)
  4. "Rapid Transport of Gases in Carbon Nanotubes," Anastasios I. Skoulidas, David M. Ackerman, J. Karl Johnson, and David S. Sholl, Phys. Rev. Lett. 89, 185901 (2002)
  5. "Adsorption of Gases in Metal Organic Materials:  Comparison of Simulations and Experiments," Giovanni Garberoglio, Anastasios I. Skoulidas, and J. Karl JohnsonJ. Phys. Chem. B 109, 13094 (2005)
Recent Publications: 
  1. "Impact of Support Interactions for Single-Atom Molybdenum Catalysts on Amorphous Silica," Christopher S. Ewing, Abhishek Bagusetty, Evan G. Patriarca, Daniel S. Lambrecht, Götz Veser, and J. Karl JohnsonInd. Eng. Chem. Res. 55, 12350 (2016)
  2. "Cavity correlation and bridge functions at high density and near the critical point: a test of second-order Percus–Yevick theory," Austin R. Saeger, J. Karl Johnson, Walter G. Chapman & Douglas Henderson, Molecular Physics 114, 2516 (2016)
  3. "Predicting catalyst-support interactions between metal nanoparticles and amorphous silica supports," Christopher S. Ewing, Götz Veser, Joseph J. McCarthy, Daniel S. Lambrecht, J. Karl JohnsonSurface Science 652, 278 (2016)
  4. "Catalytic hydrogenation of CO2 to methanol in a Lewis pair functionalized MOF," Jingyun Ye and J. Karl JohnsonCatal. Sci. Technol. 6, 8392 (2016)
  5. "Screening Lewis Pair Moieties for Catalytic Hydrogenation of CO2 in Functionalized UiO-66," Jingyun Ye and J. Karl JohnsonACS Catal 5, 6219 (2015)

Quantum-Engineered Catalysts that Turn Excess Atmospheric CO2 into Liquid Fuel

  • By Aude Marjolin
  • 8 December 2015

PQI faculty Karl Johnson and his team recently identified the two main factors for determining the optimal catalyst for turning atmospheric CO2 into liquid fuel. The results of the study, which appeared in the journal ACS Catalysis, will streamline the search for an inexpensive yet highly effective new catalyst.

Imagine a power plant that takes the excess carbon dioxide (CO2) put in the atmosphere by burning fossil fuels and converts it back into fuel. Now imagine that power plant uses only a little water and the energy in sunlight to operate. The power plant wouldn't burn fossil fuels and would actually reduce the amount of CO2 in the atmosphere during the manufacturing process. For millions of years, actual plants have been using water, sunlight, and CO2 to create sugars that allow them to grow. Scientists around the globe are now adopting their energy-producing behavior.

 

John Keith Receives ACS Petroleum Research Fund to Study CO2 Recycling Catalysts

  • By Aude Marjolin
  • 24 July 2015

To further his research in renewable energy catalysts, the American Chemical Society Petroleum Research Fund recently awarded a Doctoral New Investigator Award to PQI faculty John A. Keith. The two-year, $110,000 grant, "Unraveling Heterocycle-Promoted Hydride Transfer Mechanisms for Energetically Efficient Fuel and Petrochemical Production" will enable Dr. Keith to study design principles for renewable energy catalysts that efficiently convert CO2 into fuels and chemicals. 

Quantum Mechanics Identifies Link Between CO2 Recycling Catalysts and Bimolecular Enzymes

  • By Aude Marjolin
  • 22 January 2015

Researchers at PQI have identified a promising design principle for renewable energy catalysts. Utilizing advanced computational modeling, researchers found that chemicals commonly found in laboratories may play a similar role as biological catalysts that nature uses for efficient energy storage.

The article, "Thermodynamic Descriptors for Molecules That Catalyze Efficient CO  Electroreductions" published in the journal ACS Catalysis, was authored by PQI faculty John A. Keith, PhD, and Aude Marjolin, PhD, a postdoctoral fellow.