(2fn) Synthetic Strategies Toward Tailored Structural Properties of Advanced Inorganic Materials to Enable the Sustainable Circular Economy

Designing chemical transformation processes for sustainable production of fuels and chemicals, and for the removal of contaminants (e.g., CO₂ removal and sequestering), requires the control over the diversity of products to mitigate waste production and energy consumption. The selective adsorption of molecules and the formation of reactive intermediates that turnover to the desired product are sensitive to the structural characteristics of the heterogeneous inorganic material. Engineering the local structure of active sites and the surrounding environments (e.g., porous cavities) in inorganic solids, in turn, becomes vital to the design of heterogeneous catalysts and adsorption materials for the next generation of sustainable processes. My research group will focus on the development of synthetic protocols for the continuous preparation of inorganic materials with tailored structural features determined by the functionality of interest (e.g., heterogeneous catalysts, adsorbents, advanced cementitious materials). My group will combine synthesis strategies, detailed adsorption and spectroscopic characterization techniques, and kinetic studies to establish synthesis-structure-function guidelines for the preparation of inorganic, porous materials with judiciously defined structural characteristics.

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

Dissertation Title: “Synthetic Strategies to Tailor Active and Defect Site Structures in Lewis Acid Zeolites for Sugar Isomerization Catalysis“

The confinement of Lewis acid centers in zeolitic micropores generates reaction environments suitable to perform stereoselective reactions of oxygenated molecules containing carbonyl groups. Turnover rates of sugar isomerization vary with the local coordination of the Lewis acid centers and the polarity of the confining environment. My PhD studies focused on the development of synthesis protocols for the preparation of microporous, solid Lewis acids to tailor the density of Sn heteroatoms, their local coordination, and the intraporous hydroxyl density in stannosilicates.¹ I developed spectroscopic characterization techniques for the identification of hydrophilic binding sites and their location within the structure of zeolitic materials. My studies also described methods to quantify the density of silanol groups within the zeolitic micropores and at the external crystallite surface.² As a result, I described the density of hydrophilic binding sites that results in the stabilization of extended networks of polar molecules within the micropores, lowering turnover rates of sugar isomerization catalysis.² This thesis highlights the development of synthesis-structure-function relationships for the preparation and characterization of catalytic materials with active and defect sites of controlled structures and quantities, and the influence of such structures on rates of biomass conversion reactions.^3,4

Postdoctoral Research (University of California-Los Angeles; Advisors: Dante Simonetti and Gaurav Sant):

Project Title: “Continuous Synthesis of Architected Cementation Agents at Reduced Carbon Intensities”

Alkali metals in synthesis growth solutions perform Al counterbalancing and templating roles during crystallization processes that lead to zeolite and silicate hydrate formation in the absence of organic structure-directing agents (OSDA). At UCLA, I have developed the facilities within the Institute for Carbon Management (ICM) to prepare microporous and mesoporous silicate hydrates that act as advanced cementitious materials in cement and concrete. Particularly, I have developed synthetic methods to control the polymorphism of zeolitic materials (and silicate hydrates) via the identity and concentration of metal cations in synthesis growth solutions. Phillipsite and tobermorite, for instance, are of particular interest because of their desirable cementitious properties. My studies elucidated that the presence of sodium and potassium in synthesis gels result in the selective precipitation of phillipsite zeolites; yet, replacing the cationic charge imparted by sodium and potassium in synthesis gels with calcium results in the crystallization of tobermorite silicate hydrates (at the same total cationic content). My contributions at UCLA have been extended to the design, validation, and implementation of flow reactors to synthesize and characterize the crystallization kinetics of zeolites and other silicate hydrates. My work as a postdoctoral researcher highlights the ubiquitous roles of metal cations during hydrothermal treatments in the absence of OSDAs, and their relevance in crystallization mechanisms that dictate zeolite polymorphism.

Teaching interests:

Inspiring future generations of chemical engineers through education and mentorship, in a classroom or in research, has been the focal point of my passion for pursuing an academic career. My educational pathway and research experiences in heterogenous catalysis required a fundamental understanding of chemical kinetics, transport, and thermodynamics (e.g., core chemical engineering courses). Though I am prepared to teach any chemical engineering course, I am particularly interested in teaching kinetics/reaction engineering and thermodynamics. As a graduate student at Purdue, I received formal training on techniques to design effective course curriculums and objectives in Educational Methods in Engineering, all of which I intend to apply for the development of elective courses related to heterogeneous catalysis, synthesis of inorganic materials, and characterization of inorganic solids. My involvement as a teaching assistant in the undergraduate reaction engineering and thermodynamics courses at Purdue led to the development of recitation materials, a variety of assessments (e.g., homework and exam problems), and the opportunity to guest lectured on the undergraduate chemical reaction engineering course. Throughout my PhD studies and as a postdoctoral researcher, I have mentored one high school, three undergraduate, and several graduate students, particularly individuals from underrepresented communities, with a focus on developing their written and verbal scientific communication skills, and essential laboratory skills. These mentorship efforts led to a publication co-authored with one of my undergraduate students.⁵ My mentoring experiences exemplify my commitment to designing diverse and inclusive learning environments in a work that I plan to continue building upon by developing an inclusive culture in my research group and seeking opportunities to recruit graduate and undergraduate students from traditionally underrepresented communities.

References:

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

[2] Vega-Vila, J. C., Gounder, R., “Quantification of Intraporous Hydrophilic Binding Sites in Lewis Acid Zeolites and Consequences for Sugar Isomerization Catalysis.” ACS Catalysis, 10 (2020) 12197-12211.

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

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

[5] Cordon, M. J., Vega-Vila, J. C., LaRue, A., Huang, Z., Gounder, R., “Tighter Confinement Increases Selectivity of D-Glucose Isomerization Toward L-Sorbose in Titanium Zeolites.” Angewandte Chemie International Edition, 59 (2020) 19102-19107.