David W. Flaherty

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• Research Synopsis
• Research Group Website

Education

• Postdoctorate, University of California at Berkeley, 2010-2012
• Ph.D. Chemical Engineering, University of Texas at Austin, 2010
• B.S. Chemical Engineering, University of California at Berkeley, 2004

Biography

Professor David W. Flaherty focuses on the overlapping topics of catalysis, surface science, and materials synthesis. He has received numerous awards including the Eastman Foundation Distinguished Lecturer in Catalysis from the University of California, Berkeley, and the Department of Energy Early Career Award. He also has been recognized for his excellence in advising and teaching students and received the SCS Excellence in Teaching Award in 2015. Flaherty joined the department in 2012. He earned his B.S. from the University of California, Berkeley in 2004 and his Ph.D. from the University of Texas at Austin in 2010. His post-doctoral work was completed at the University of California, Berkeley.

Research Statement

Production and Use of Selective Oxidants

Hydrogen peroxide (H2O2) is a selective oxidant for epoxidation reactions and an environmentally friendly alternative to chlorine-based oxidizers. Direct synthesis of H2O2 (DS) from H2 and O2 is an appealing reaction which could reduce the cost or H2O2 production and allow it to be produced on-site or in situ. Pd-Au alloys give high selectivities and rates, however, few mechanistic studies have been performed and computational hypotheses on the origin of the selectivity of these materials have yet to be confirmed. We are studying the mechanism of DS to determine how the addition of Au to Pd improves H2O2 selectivity. We use our findings to synthesize new catalytic structures (clusters and organometallic complexes) for DS that may replace Pd and Au with more selective and earth-abundant materials. 

Acid-Base Cooperativity in C-C Bond Formation Reaction

Chemical catalysis can be used to transform oxygenated organic molecules into platform chemicals that can replace their analogs derived from petroleum. Metal oxides form C-C bonds by aldol additions (AA) of ethanol from biomass fermentation, to produce longer chain alcohols that can be converted into valuable chemicals.  Amphoteric metal oxides with vicinal acidic and basic sites of moderate strength promote these reactions at rates much greater than expected based on the strength of their basic and acidic sites alone, which suggests that these systems operate by cooperative catalytic mechanisms that simultaneously stabilize reactive species. We are working to determine the mechanistic and kinetic differences between AA on amphoteric and basic metal oxides in order to quantify the cooperative interactions and how they influence reaction rates and product selectivities. These results are used to tailor the acid-base properties of surfaces in order to control the degree of branching within AA product distributions.

Thermodynamic and Kinetic Relationships in Solid Acids 

Solid acid catalysts are widely used to refine petrochemicals, often as microporous zeolites. Rates and selectivities of acid-catalyzed reactions depend on the acid strength of the solid material, however, established scales of acid strength (e.g., pKa or proton affinities) are not applicable to solids. Moreover, common experimental approaches to measure acid strength are misleading, because they do not differentiate between stabilizing contributions from protonation energies and van der Waal’s solvation. We are working to quantify how the acid-strength depends on the location and identity of acid moieties including isomorphous substituent atoms (ISA) in microporous silicates. Our synthetic and analytical approach enables us to independently measure the stabilization energy associated with acid strength and van der Waal’s forces.  Thermodynamic acid-strengths will be correlated to kinetics that determine reaction rates and selectivities for probe reactions to show how “acidity” influences catalysis. These results are needed to inform the design of technical materials that increase yields of desirable products from petroleum or biomass.

Removal of Heteroatoms from Organic Molecules by Hydrogenolysis

Catalytic hydrogenolysis of C-O, C-S, and C-N bonds while preserving C-C bonds can produce valuable platform chemicals. Bimetallic clusters that contain a noble metal (NM; e.g., Ir) and an oxophilic metal (OM; e.g., Re) catalyze hydrogenolysis of oxygenates with higher turnover rates and greater selectivities towards hindered C-O bonds than pure NM clusters or isolated Brønsted acid (BA) sites. The unique reactivity of these bimetallic clusters is thought to be due to a small subset of all the surface sites, NM-BA site pairs, that form in the presence of moisture. However, it is not clear how the presence of NM-BA site pairs change the reaction network, rate constants, and activation barriers. The dearth of fundamental understanding currently prevents systematic development of new processes and catalysts that take advantage of this phenomenon. We aim to develop an atomic-scale description of how NM-BA site pairs cooperate to selectively cleave C-O, C-S, and C-N bonds. These results will increase fundamental understanding of cooperative catalysis and will impact development of catalysts and processes for biomass upgrading and heteratom removal from fossil feed streams. 

Post-Doctoral Research Opportunities

Currently, we do not have funding to support post-doctoral fellows. However, researchers with independent support are encouraged to contact us to inquire about possible projects. Please include a cover letter stating research interests, a current CV, and a list of three references with email addresses and phone numbers.

Graduate Research Opportunities

In Fall 2012, 2-4 positions are available for ambitious researchers who have been admitted into the Department of Chemical and Biomolecular Engineering at UIUC. Our research is very "hands-on." All students will build and operate experimental systems (catalysis units, vacuum systems, and characterization equipment). Previous experience using a wrench, programming in LabView, or with synthesizing materials is helpful.

Research Interests

• Catalysis, surface science and materials synthesis

Selected Articles in Journals

• Jason S. Adams, Ashwin Chemburkar, Pranjali Priyadarshini, Tomas Ricciardulli, Yubing Lu, Ayman M. Karim, Stuart Winikoff, Matthew Neurock, and David W. Flaherty, “Solvent Molecules Form Surface Redox Mediators In Situ and Cocatalyze O2 Reduction on Pd” Science 2021, 371, 626-632.
• Jason Adams, Matthew Kromer, Joaquín Rodríguez-López, David Flaherty, “Unifying Concepts in Electro- and Thermocatalysis towards Hydrogen Peroxide Production“, J. Am. Chem. Soc. 2021, 143, 7940-7957.
• Tomas Ricciardulli, Sahithi Gorthy, Jason Adams, Coogan Thompson, Ayman Karim, Matthew Neurock, David Flaherty, “Effect of Pd Coordination and Isolation on the Catalytic Reduction of O2 to H2O2 over PdAu Bimetallic Nanoparticles”, J. Am. Chem. Soc. 2021, 143, 5445-5464.
• Gina Noh, Erwin Lam, Daniel T. Bregante, Jordan Meyet, Petr Sot, David W. Flaherty, Christophe Copéret, “Lewis Acid Strength of Interfacial Metal Sites Drives CH3OH Selectivity and Formation Rates on Cu-based Hydrogenation Catalysts”, Angew. Chem. Int. Ed., 2021, 60, 9650-9659.
• Anda Sulce, David Flaherty, Sebastian Kunz, “Kinetic Analysis of the Asymmetric Hydrogenation of ß-Keto Esters over a-Amino Acid-Functionalized Pt Nanoparticles”, J. Catal., (2019), 374, 82-92.
• D. T. Bregante, Alayna M. Johnson, Ami Y. Patel, E. Zeynep Ayla, Michael J. Cordon, Brandon C. Bukowski, Jeffrey Greeley, Rajamani Gounder, David W. Flaherty, “Cooperative Effects between Hydrophilic Pores and Solvents: Catalytic Consequences of Hydrogen Bonding on Alkene Epoxidation in Zeolites" J. Am. Chem. Soc., 2019, 141, 7302-7319.
• A. Sampath, S. A. Chang, D. W. Flaherty, “Catalytic Hydrogen Transfer and Decarbonylation of Aromatic Aldehydes on Ruthenium Phosphide,” J. Phys. Chem. C 122 (2018) 23600-23609.
• M. J. Cordon, J. W. Harris, J. C. Vega-Vila, J. S. Bates, M. Gupta, S. Kaur, M. E. Witzke, E. C. Wegener, J. T. Miller, D. W. Flaherty, D. D. Hibbitts, R. Gounder, “The Dominant Role of Entropy in Stabilizing Sugar Isomerization Transition States within Hydrophobic Zeolite Pores,” J. Am. Chem. Soc. 140 (2018) 14244-14266.
• N. M. Wilson, J. M. Schröder, P. Pranjali, D. T. Bregante, S. Kunz, D. W. Flaherty, “Direct Synthesis of H2O2 on PdZn Nanoparticles: The Impact of Electronic Modifications and Heterogeneity of Active Sites,” J. Catal. 368 (2018) 261-274.
• M. E. Witzke, A. Almithin, C. L. Coonrod, D. D. Hibbitts, D. W. Flaherty, “Mechanism and Site Requirements for C-O Bond Rupture on Ni and Ni-Phosphide Surfaces,” ACS Catal. 8 (2018) 7141-7157.
• D. T. Bregante, A. Y. Patel, A. M. Johnson, D. W. Flaherty, “Catalytic Thiophene Oxidation by Groups 4 and 5 Framework-Substituted Zeolites with Hydrogen Peroxide: Mechanistic and Spectroscopic Evidence for the Effects of Metal Lewis Acidity and Solvent Lewis Basicity,” J. Catal. 364 (2018) 415-425.
• H.-B. Zhang, M. Y. S. Ibrahim, D. W. Flaherty, “Mechanisms of C-C Bond Formation and Influence of Thermal Treatments for Aldol Addition on TiO2 Catalysts,” J. Catal. 361 (2018) 290-302.
• N. M. Wilson, Y.-T. Pan, Y.-T. Shao, J.-M. Zuo, H. Yang, D. W. Flaherty, “Direct Synthesis of H2O2 on AgPt Intermetallic Octahedrons: Importance of Pt-Ag Interactions for High H2O2 Selectivities,” ACS Catal. 8 (2018) 2880-2889.
• D. T. Bregante, N. E. Thornburg, J. M. Notestein, D. W. Flaherty, “Consequences of Confinement for Alkene Epoxidation with Hydrogen Peroxide on Highly Dispersed Group IV and V Metal Oxide Catalysts,” ACS Catal. 8 (2018) 2995-3010. Featured on the cover of ACS Catalysis.
• D. W. Flaherty, “Direct Synthesis of H2O2 from H2 and O2 on Pd Catalysts: Current Understanding, Outstanding Questions, and Research Needs,” ACS Catal. 8 (2018) 1520-1527. Invited Viewpoint for ACS Catalysis.
• N. M. Wilson, P. Priyadarshini, S. Kunz, D. W. Flaherty, “Direct Synthesis of H2O2 on Pd and AuPd Clusters: Understanding the Effects of Alloying Pd with Au,” J. Catal. 357 (2018) 163-175.
• S. A. Chang, V. Vermani, D. W. Flaherty, "Effects of Phosphorus on Bond Rupture in Acetic Acid Decomposition over Ru (0001) and Px-Ru(0001)," J. Catal. 353 (2017) 181-191.
• S. A. Chang, V. Vermani, D. W. Flaherty, "Effects of Phosphorus and Alkyl Substituents on C-H, C-C, and C-O Bond Rupture within Carboxylic Acids on Ru(0001)," J. Vac. Sci. Tech. A. 35 (2017) 05C309.
• D. T. Bregante, D. W. Flaherty, “Periodic Trends in Olefin Epoxidation over Group IV and Group V Framework Substituted Zeolite Catalysts: A Kinetic and Spectroscopic Study,” J. Am. Chem. Soc. 139 (2017) 6888-6898. This article was featured by the Illinois News Bureau, Phys.org, EurekaAlert!m ChemEurope, and other sources.
• T. Moteki, A. T. Rowley, D. T. Bregante, D. W. Flaherty, “Pathways toward 2- and 4-Methylbenzaldehyde via Sequential Reactions from Acetaldehyde over Hydroxyapatite Catalysts,” ChemCatChem 9 (2017) 1921-1929.
• D. T. Bregante, P. Priyadarshini, D. W. Flaherty, “Kinetic and Spectroscopic Evidence for Reaction Pathways and Intermediates for Olefin Epoxidation on Nb in *BEA,” J. Catal. 348 (2017) 75-89.
• M. E. Witzke, P. J. Dietrich, M. Y. S. Ibrahim, K. Al-Bardan, M. Triezenberg, D. W. Flaherty, “Spectroscopic Evidence for Origins of Size and Support Effects on Selectivity of Cu Nanoparticle Dehydrogenation Catalysts,” Chem. Comm. 53 (2017) 597-600.
• N. M. Wilson, D. T. Bregante, P. Priyadarshini, D. W. Flaherty, “Production and Use of H2O2 for Atom-Efficient Functionalization of Hydrocarbons and Small Molecules,” Catalysis 29 (2017) 122-212.
• S. A. Chang, D. W. Flaherty, “Mechanistic Study of Formic Acid Decomposition over Ru(0001) and Px-Ru(0001): Effects of Phosphorous on C-H and C-O Bond Rupture,” J. Phys. Chem. C 120 (2016) 25425-25435.
• T. Moteki, D. W. Flaherty, “Self-Terminated Reaction Pathways that Produce C8 Aromatics from Bioethanol,” ACS Catal. 6 (2016) 7278-7282.
• Lipeng Wu, Takahiko Moteki, Amit A. Gokhale, David W. Flaherty, F. Dean Toste, “Production of Fuels and Chemicals from Biomass: Condensation Reactions and Beyond” Chem 1 (2016) 32-58.
• Takahiko Moteki, David W. Flaherty, “Mechanistic Insight to C-C Bond Formation and Predictive Models for Cascade Reactions among Alcohols on Ca- and Sr-Hydroxyapatites” ACS Catal. 6 (2016) 4170-4183. This article was selected as an “ACS Editor’s Choice” and a “Most Read Article” of ACS Catalysis, Spring 2016.
• Neil Wilson, David W. Flaherty, “Mechanism for the Direct Synthesis of H2O2 on Pd Clusters: Heterolytic Reaction Pathways at the Liquid-Solid Interface,” J. Am. Chem. Soc. 138 (2016) 574-586. Featured on the cover of J. Am. Chem. Soc. This article was selected as an “ACS Editor’s Choice” and was highlighted in Chemical & Engineering News (December, 7th, 2015), EurekAlert!, ChemEurope, etc.
• David D. Hibbitts, David W. Flaherty, Enrique Iglesia, “ Effects of Chain Length and van der Waals nteractions on the Mechanism and Rates of Metal-Catalyzed Hydrogenolysis of n-Alkanes,” J. Phys. Chem. C 120 (2016) 8125-8138.
• David W. Flaherty, Alper Uzun, Enrique Iglesia, “Catalytic Ring Opening of Cycloalkanes on Ir Clusters: Alkyl Substitution Effects on the Structure and Stability of C-C Bond Cleavage Transition States,” J. Phys. Chem. C 119 (2015) 2597-2613.
• Wen-Yueh Yu, Gregory M. Mullen, David W. Flaherty, and C. Buddie Mullins, "Selective Hydrogen Production from Formic Acid Decomposition on Pd-Au Bimetallic Surfaces," J. Am. Chem. Soc. 136 (2014) 11070-11078.
• David W. Flaherty, David D. Hibbitts, Enrique Iglesia, “Metal-Catalyzed C-C Bond Cleavage in Alkanes: Effects of Methyl Substitution on Transition State Structures and Stability,” J. Am. Chem. Soc. 136 (2014) 9664-9676.
• David W. Flaherty, David D. Hibbitts, Elif Gurbuz, Enrique Iglesia, “Theoretical and Kinetic Assessment of the Mechanism of Ethane Hydrogenolysis on Metal Surfaces Saturated with Chemisorbed Hydrogen,” J. Catal. 311 (2014) 350-356.
• David W. Flaherty, Enrique Iglesia, “Enthalpic and Entropic Contributions that Determine Rates and Positions of C-C Bond Cleavage in n-Alkanes,” J. Am. Chem. Soc. 135 (2013) 18586-18599.

Honors

• Eastman Foundation Distinguished Lecturer in Catalysis, University of California, Berkeley (2021)
• Department of Energy, Early Career Award (2019)
• Early Career Advisory Board, ACS Catalysis (2019)
• Dean’s Award for Research Excellence, College of Engineering, University of Illinois (2018)
• Early Career Research Award, American Vacuum Society, Prairie Chapter (2018)
• National Science Foundation CAREER Award (2016)
• School of Chemical Sciences, Excellence in Teaching (2015)
• Named to the College of Engineering "Outstanding Advisors List" (2014, 2015)
• ACS PRF Doctoral New Investigator Award (2014)
• Seven times included on the "List of Teachers Ranked as Excellent by Their Students" (2013-2021)
• Dow Chemical Company Faculty Scholar (2012-2017)

Teaching Honors

• Seven times included on the "List of Teachers Ranked as Excellent by Their Students" (2013-2015)
• Named to the College of Engineering "Outstanding Advisors List" (2014, 2015)

Research Honors

• ACS PRF Doctoral New Investigator Award (2013)
• Dean’s Award for Research Excellence, College of Engineering, University of Illinois (2018)
• Early Career Research Award, American Vacuum Society, Prairie Chapter (2018)
• Department of Energy, Early Career Award (2019)
• Eastman Foundation Distinguished Lecturer in Catalysis, University of California, Berkeley (2021)

Recent Courses Taught

• CHBE 422 - Mass Transfer Operations
• CHBE 424 - Chemical Reaction Engineering
• CHBE 551 (CHEM 582) - Chemical Kinetics & Catalysis