Faculty Profile

David W. Flaherty

Chemical and Biomolecular Engineering
David W. Flaherty
David W. Flaherty
Assistant Professor, Dow Chemical Company Faculty Scholar
125 Roger Adams Laboratory MC 712
600 S. Mathews
Urbana Illinois 61801
(217) 244-2816

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

David W. Flaherty is an Assistant Professor and Dow Chemical Faculty in the Department of Chemical and Biomolecular Engineering. Research in the Flaherty Lab focuses on the overlapping topics of catalysis, surface science, and materials synthesis. Dr. Flaherty has received a number of notable awards in recent years, including the National Science Foundation CAREER Award and the New Investigator Award from the American Chemical Society. He also has been recognized for his excellence in advising and teaching students and received the SCS Excellence in Teaching Award in 2015. Dr. 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.

Academic Positions

  • Assistant Professor, Department of Chemical and Biomolecular Engineering

For more information

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

Honors

  • National Science Foundation CAREER Award (2016)
  • ACS PRF Doctoral New Investigator Award (2013)
  • Named to the College of Engineering "Outstanding Advisors List" (2014, 2015)
  • Four times included on the "List of Teachers Ranked as Excellent by Their Students" (2013-2015)

Teaching Honors

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

Research Honors

  • ACS PRF Doctoral New Investigator Award (2013)