(3bs) Engineering Porous Catalytic Materials for Responsible Production and Use of Fuels and Chemicals

Solid catalytic materials have long been a cornerstone for the production and consumption of fuels and chemicals, and the continued design and understanding of such materials is critical for the development of new processes and technologies that minimize their environmental impact. Heterogeneous catalysts can be engineered over a range of length scales, from larger than a micron to sub-nanometer, to influence transport phenomena that regulate molecular traffic to and from catalytic active sites. The diversity of catalytic solids arises from the complex interplay of chemical interactions that modify active sites due to variation in the secondary environment that solvates reactive intermediates, the presence of spectator molecules that may promote or inhibit catalysis, and dynamic processes that take place during catalysis. My group will utilize synthetic methods to prepare catalytic materials with well-defined diffusion pathlengths and active site structure, detailed kinetic and isotopic studies to probe mechanistic aspects of surface-catalyzed reactions, and spectroscopic methods that interrogate active sites in operando. Specific research themes will focus on: (1) developing synthetic methods to manipulate the placement of non-catalytic moieties near catalytic active sites that modify reaction rates and selectivities, (2) bridging fundamental kinetic studies with spectroscopic methods that elucidate how changes to the secondary solvating environment alter the energetics of adsorbed intermediates and transition states, and (3) furthering the understanding of how hydrogen-bonding networks influence adsorption and catalysis within porous materials.

PhD Research (Purdue University; Advisor: Rajamani Gounder):

Dissertation Title: “Synthetic Methods to Control Aluminum Proximity in Chabazite Zeolites and Consequences for Acid and Redox Catalysis”

The ability to predictably alter the structure and proximity of active sites in solid catalysts enables designing materials with tailored catalytic and adsorption properties. During my graduate studies, I developed synthetic methods to control the proximity of framework Al atoms in aluminosilicate zeolites crystallized using mixtures of different organic and inorganic structure-directing agent (SDA) cations. This effort required developing new experimental methods to precisely quantify such proximal active sites. The occlusion of cationic SDAs of different size and charge density leads to either cooperative or competitive electrostatic interactions that bias the placement of framework Al atoms in different arrangements, in a manner that systematically depends on the inorganic-to-organic SDA ratio used in crystallization media.^1,2 Different Al-Al arrangements lead to order-of-magnitude differences in alcohol dehydration rate constants^3,4 and to different structures of mono- or divalent Cu cations and oxo-complexes that are active sites for the selective catalytic reduction of NOx with NH₃, which is a commercial technology used in diesel exhaust aftertreatment.^5-7

Postdoctoral Research (Massachusetts Institute of Technology; Advisor: Yuriy Román-Leshkov):

Project Title: “Influence of Confined Solvent Structure on Catalysis in Liquid Media”

The complexation of reactant molecules within enzyme catalysts often results in substantial disruption and displacement of ordered water molecules originally positioned within hydrophobic reaction pockets that surround the active metal center. The evolutionary ability of enzymes to enhance rates of reaction by controlling the structure of confined solvent molecules has spurred interest in the development of zeolite catalysts as artificial analogues. My postdoctoral research focuses on understanding how solvent polarity influences catalysis in liquid media when active sites and solvent molecules are confined within the sub-nanometer pores of hydrophobic or hydrophilic zeolite catalysts. Spectroscopic investigation of adsorbed solvent molecules reveal that the polarity of the zeolite pore regulates the structure of the confined solvent, causing rates of transfer hydrogenation to become 5-10x larger in hydrophobic than in hydrophilic zeolite pores. Detailed kinetic studies show that diverse solvent environments alter the thermodynamics of reactant adsorption and that the polarity of the zeolite framework selectively partitions reactant and solvent molecules between the bulk and adsorbed phases. These findings resemble observations in biological catalysis and provide mechanistic insight into how the structure of confined solvent molecules and the energetics of adsorbed intermediates depend on the polarity of the confining reaction environment provided by zeolite micropores.

Teaching Interests:

I am comfortable teaching any core Chemical Engineering course, and am particularly interested in teaching Chemical Reaction Engineering and Thermodynamics courses at the undergraduate and graduate levels. I envision developing elective courses focused on heterogeneous catalysis and on materials and catalyst characterization. As a graduate student, I had the opportunity to be a teaching assistant for undergraduate chemical reaction engineering where, in addition to leading recitation sections and designing problem sets, I served as a guest lecturer and laboratory instructor. During my time as a teaching assistant, I was awarded a campus-wide Purdue Teaching Academy Graduate Teaching Award. I have also mentored undergraduate researchers and graduate students where I focused on developing foundational laboratory skills, including the measurement and interpretation of chemical kinetics and synthesis of catalytic materials, and communication skills, including effective presentation strategies and scientific manuscript writing. As a teacher and a mentor, it is my responsibility to be aware of and speak out against biases and discrimination in the classroom and laboratory environments. I am committed to taking action to support and promote diversity and inclusivity in science by being a mentor to and supporting those who come from traditionally under-represented backgrounds, educating myself and others about the systemic biases present in the scientific community, and encouraging the recruitment of a diverse team of students and fellow faculty.

(1) Di Iorio, J. R.; Gounder, R. Chemistry of Materials 2016, 28, 2236-2247.

(2) Di Iorio, J. R.; Li, S.; Jones, C. B.; Nimlos, C. T.; Wang, Y.; Kunkes, E.; Vattipalli, V.; Prasad, S.; Moini, A.; Schneider, W. F.; Gounder, R. Journal of the American Chemical Society 2020, 142, 4807-4819.

(3) Di Iorio, J. R.; Hoffman, A. J.; Nimlos, C. T.; Nystrom, S.; Hibbitts, D.; Gounder, R. Journal of Catalysis 2019, 380, 161-177.

(4) Di Iorio, J. R.; Nimlos, C. T.; Gounder, R. ACS Catalysis 2017, 7, 6663-6674.

(5) Di Iorio, J. R.; Bates, S. A.; Verma, A. A.; Delgass, W. N.; Ribeiro, F. H.; Miller, J. T.; Gounder, R. Topics in Catalysis 2015, 58, 424-434.

(6) Paolucci, C.; Khurana, I.; Parekh, A. A.; Li, S.; Shih, A. J.; Li, H.; Di Iorio, J. R.; Albarracin-Caballero, J. D.; Yezerets, A.; Miller, J. T.; Delgass, W. N.; Ribeiro, F. H.; Schneider, W. F.; Gounder, R. Science 2017, 357, 898.

(7) Paolucci, C.; Parekh, A. A.; Khurana, I.; Di Iorio, J. R.; Li, H.; Albarracin Caballero, J. D.; Shih, A. J.; Anggara, T.; Delgass, W. N.; Miller, J. T.; Ribeiro, F. H.; Gounder, R.; Schneider, W. F. Journal of the American Chemical Society 2016, 138, 6028-6048.