Heterogeneous catalysis is an integral component of many technologies that drive our chemical and energy industries. We are an experimental research group that studies the fundamentals and applications of heterogeneous catalysis and the targeted synthesis of inorganic solids and molecular sieves. We combine approaches in materials synthesis, characterization, and kinetic and mechanistic studies to probe the site requirements, reactive intermediates and elementary steps that constitute reaction mechanisms. We aim to develop structure-function relations that predict how reactant and catalyst structures influence reactivity and selectivity, in order to inform catalyst design and selection for new and existing catalytic processes.

Our current research interests fall within the following areas:
(i) catalytic routes and materials that enable the conversion of petroleum- and natural gas-derived hydrocarbons to transportation fuels and chemicals
(ii) catalyst design for selective reactions of multifunctional and polyfunctional molecules, such as those derived from renewable biomass, in liquid and gaseous phases
(iii) selective catalytic reduction of NOx (x = 1, 2) compounds with ammonia for pollution abatement in lean-burn engine emissions

We also focus on investigating microporous and mesoporous materials, zeolites, and molecular sieves, which are prevalent in the petrochemical refining and chemical industries. These crystalline oxides contain catalytically active sites confined within ordered void spaces (channels, cages, pockets) of molecular dimension (typically <2 nm). The properties of both the active sites and the confining environments can strongly influence catalytic rates and selectivities. In certain contexts, synthetic molecular sieves show catalytic reactivity and specificity reminiscent of that displayed by biological enzymes. One long-term goal of our research program is to understand fundamentally why and when synthetic materials exhibit such remarkable catalytic behavior.

We are a part of the Purdue Catalysis Center, which fosters interaction among faculty and students in catalysis research groups by collaborating on research projects, sharing resources and facilities, and holding weekly joint group meetings.

"Mechanistic Origins of the High-Pressure Inhibition of Methanol Dehydration Rates in Small-Pore Acidic Zeolites", J. R. Di Iorio, A. J. Hoffman, C. T. Nimlos, S. Nystrom, D. Hibbitts, R. Gounder. Journal of Catalysis, 380, 161-177 (2019).

"Influence of Tetrapropylammonium and Ethylenediamine Structure-Directing Agents on the Framework Al Distribution in B-Al-MFI Zeolites", Y. G. Hur, P. M. Kester, C. T. Nimlos, Y. Cho, J. T. Miller, R. Gounder, Industrial & Engineering Chemistry Research, 58, 11849-11860 (2019).

"Distinct Catalytic Reactivity of Sn Substituted in Framework Locations and at Defect Grain Boundaries in Sn-Zeolites" J. S. Bates, B. C. Bukowski, J. W. Harris, J. Greeley, R. Gounder. ACS Catalysis, 9, 6146-6168 (2019).

"Evidence for the Coordination-Insertion Mechanism of Ethene Dimerization at Nickel Cations Exchanged onto Beta Molecular Sieves" R. Joshi, G. Zhang, J. T. Miller, R. Gounder. ACS Catalysis, 8, 11407-11422, (2018).

"Dominant Role of Entropy in Stabilizing Sugar Isomerization Transition States within Hydrophobic Zeolite Pores" M. J. Cordon, J. W. Harris, J. C. Vega-Vila, J. S. Bates, S. Kaur, M. Gupta, M. E. Witzke, E. C. Wegener, J. T. Miller, D. W. Flaherty, D. D. Hibbitts, R. Gounder. Journal of the American Chemical Society, 140, 14244-14266, (2018).

"Influence of Confining Environment Polarity on Ethanol Dehydration Catalysis by Lewis Acid Zeolites" J. S. Bates, R. Gounder. Journal of Catalysis, 365, 213-226, (2018).

"Ammonia Titration Methods to Quantify Bronsted Acid Sites in Zeolites Substituted with Aluminum and Boron Heteroatoms" P. M. Kester, J. T. Miller, R. Gounder. Industrial & Engineering Chemistry Research, 57, 6673-6683, (2018).

"Consideration of the Aluminum Distribution in Zeolites in Theoretical and Experimental Catalysis Research" B. C. Knott, C. T. Nimlos, D. J. Robichaud, M. R. Nimlos, S. Kim, R. Gounder. ACS Catalysis, 8, 770-784, (2018).

"Dynamic Multinuclear Sites Formed by Mobilized Copper Ions in NOx Selective Catalytic Reduction" C. Paolucci, I. Khurana, A. A. Parekh, S. Li, A. J. Shih, H. Li, J. R. Di Iorio, J. D. Albarracin-Caballero, A. Yezerets, J. T. Miller, W. N. Delgass, F. H. Ribeiro, W. F. Schneider, R. Gounder, Science, 357, 898-903, (2017).

"Introducing Catalytic Diversity into Single-Site Chabazite Zeolites of Fixed Composition via Synthetic Control of Active Site Proximity" J. R. Di Iorio, C. T. Nimlos, R. Gounder, ACS Catalysis, 7, 6663-6674, (2017).

"Controlled Insertion of Tin Atoms into Zeolite Framework Vacancies and Consequences for Glucose Isomerization Catalysis" J. C. Vega-Vila, J. W. Harris, R. Gounder, Journal of Catalysis, 344, 108-120, (2016).

"Controlling the Isolation and Pairing of Aluminum in Chabazite Zeolites Using Mixtures of Organic and Inorganic Structure-Directing Agents" J. R. Di Iorio, R. Gounder, Chemistry of Materials, 28, 2236-2247, (2016).

"Titration and Quantification of Open and Closed Lewis Acid Sites in Sn-Beta Zeolites that Catalyze Glucose Isomerization", J. W. Harris, M. J. Cordon, J. R. Di Iorio, J. C. Vega-Vila, F. H. Ribeiro, R. Gounder, Journal of Catalysis, 335, 141-154, (2016).