(7ej) Enabling New Reaction Pathways through Creation of Tailored Molecular Sieve Catalysts

Research
Interests:

New catalysts enabled the creation of
many important technologies in the 20^th century. For example,
processes such as ammonia synthesis for fertilizer, fluidized catalytic
cracking for high-octane gasoline, olefin polymerization for plastics and
elastomers, and three-way catalytic converters for automotive emissions control
all have made very large, positive impacts on society. Effective use of
heterogeneous catalysts in future applications for key areas of interest, such
as energy, consumer goods, and infrastructure, requires both rational design of
these nanomaterials at the molecular level and development of new, alternative
routes to produce high-value chemicals from carbon-containing resources.

The increased accessibility of
unconventional gas sources in shale formations throughout the world presents an
unprecedented opportunity to devise new reaction pathways to transform lower
alkanes, such as methane (CH₄), into a diverse range of suitable
chemical precursors with enhanced selectivity and reduced environmental impact.
One possible strategy for harnessing CH₄ as a chemical
feedstock in the near-term is through formaldehyde (CH₂O): the
simplest alkanal derived from CH₄ via methanol (CH₃OH)
and synthesis gas (CO/CO₂/H₂) that can serve as a primary
building block molecule (Scheme 1, blue path). Drawing from the concept of the
formose reaction for sugar synthesis in prebiotic chemistry, I propose to
combine CH₂O with biomass-derived glycolaldehyde (diose) through a
series of intermolecular C-C coupling reactions over molecular sieve catalysts
to produce a variety of useful oxygenated intermediates (e.g., alpha-hydroxy
carboxylic acids, esters, ketones) and simple carbohydrates (e.g., trioses) in
alcoholic and aqueous media. In addition to its viability for terrestrial
chemicals production, CH₂O may also hold long-term promise for
synthesis of edible, chiral sugars (e.g., D-glucose) from CO₂ and
H₂ during extended missions in space and on Mars (Scheme 1, red
path).

For this approach, I will use the
catalytic functionalization of CH₂O, a model chemical building block,
as a core research theme (Scheme 1, outlined region) to support the development
of short- and long-term projects in areas such as:

1) Design, synthesis, and
application of tailored molecular sieves

By combining a priori prediction
of energetically favorable organic structure directing agents (OSDAs) and
knowledge of organic-inorganic guest-host interactions, I will selectively
produce targeted molecular sieves - the beginning elements of such a
methodology have been successfully demonstrated in academia by the Davis
research group at Caltech in combination with the Deem research group at Rice
University. I plan to capitalize on their early successes and further develop
this methodology using the reaction pathways outlined above as the initial
system for implementation.

Additional research focuses will include:

• Experimentally deriving structure-property relationships to guide computationally-driven design and synthesis of new molecular sieve frameworks and compositions
• Examining effects of OSDAs and synthesis conditions on framework topology, intra-crystalline acid and metal site functionality, and enantioselectivity
• Investigating molecular sieve performance for adsorption and separation of oxygenates and carbohydrates
• Exploring catalytic functionality for chiral assembly of small molecules

2) Assessment of catalytic active
site function, tunability, and mechanistic implications

Once the new structures are developed, I
will utilize existing characterization methods to investigate the ability of
acid and metal centers in these molecular sieves to manipulate CH₂O
carbonyl functionality and catalyze reactions involving C-C and C-O bond
formation as well as intramolecular carbon and hydrogen shift reactions.

Furthermore, I aim to:

• Understand the influences of molecular sieve pore structure, active site confinement, and local geometric and electronic structure on product selectivities and turnover frequencies for the reaction pathways outlined above
• Elucidate key reaction pathways and determine the relevant kinetic parameters for these systems by combining in situ and operando spectroscopic techniques with isotopic labeling experiments

Teaching
Interests:

A student-focused teaching approach that
values and facilitates individual learning is essential for more effective
chemical engineering instruction. Students must not only become proficient at
problem solving, but must learn to think for themselves, cultivate a sense of
professionalism, and develop critical skills needed to succeed as practicing
engineers. Engineering coursework is especially conducive to this type of
multi-faceted learning approach because of the ability to integrate theory with
practical applications. However, the critical link between principles and
practice, which can be a powerful motivator for learning in many students, is
often missing from the college classroom. Thus, one of my primary objectives as
an instructor is to bridge this gap and help students organize theory and facts
and apply these concepts to solve new problems.

Students will be introduced to theory
through traditional, lecture-based instruction that will be supplemented with
real-world examples to model scenarios that the students could encounter as
practicing engineers. The appropriate mix of theory and application will be
dependent upon the exact nature of the course as well as the audience. For
instance, undergraduate students may be more interested and receptive to
examples that are industrially-relevant, whereas graduate students may
appreciate topics more closely tied to research and development in a laboratory
environment. Potential teaching methods include:

• Conducting break-out sessions and solving short problems in small teams
• Demonstrating the use of software tools to solve more complex problems
• Performing small-scale experiments (if possible) to supplement course concepts
• Evaluating case studies on relevant incidents in industry and academia
• Discussions with invited guest speakers

Throughout my instruction, I will
integrate themes of ethics, professionalism, and process safety into the
curriculum that align with the course objectives. Having early exposure to
these topics will help inform how students approach problem solving in their
future work by enabling them to consider the potential impacts of decisions
that engineers may face.

Core courses that I am most interested in
teaching include kinetics and reaction engineering, thermodynamics, mass and
energy balances, unit operations, and engineering materials. Additionally, I
would also like to design new upper-level undergraduate and graduate courses in
engineering ethics for safety and the environment, industrial catalysis and
chemical technology, catalysis and spectroscopic methods, and engineering
entrepreneurship.