Public Abstract

DE-SC0024448: Understanding earth-abundant single-site heterogeneous catalysts for energy and sustainability-critical transformations

Award Status: Active

Institution: Northwestern University, Chicago, IL
UEI: EXZVPWZBLUE8
DUNS: 160079455

Most Recent Award Date: 09/20/2023
Number of Support Periods: 1
PM: Bradley, Christopher

Current Budget Period: 09/01/2023 - 08/31/2024
Current Project Period: 09/01/2023 - 08/31/2026
PI: Marks, Tobin

Supplement Budget Period: N/A

Public Abstract

With the support of the DOE/BES Catalysis Science Program, Professors Tobin Marks and Michael Bedzyk of Northwestern University are discovering, characterizing, understanding, and optimizing for implementation, new catalytic reactions, and closely combining this research effort with educational outreach activities. Such catalytic processes are of great importance to the U.S. economy, and it is estimated that catalysis underlies approximately 35% of the U.S. GDP, producing coatings, fertilizers, fuels, plastics, pharmaceuticals, medical garments and equipment, and other chemicals on a vast scale. In the future, these important catalytic transformations must be more energy- and resource-efficient, non-toxic, non-polluting, and rely on low-cost, earth-abundant metals in more selective, sustainable, and economically competitive technologies. Tackling these important challenges will require a highly educated and diverse/inclusive National technical workforce, and US universities must play an essential role by broadly educating young scientists to attack global-scale problems, while carrying out forefront research across broad disciplinary fields. The projects funded by this award will involve a transdisciplinary, educationally rigorous mix of catalyst creation, catalyst evaluation, and understanding the pathways by which catalytic products are formed. These activities when combined with highly interactive research group environments will provide excellent training/mentoring for graduate, undergraduate, and postdoctoral students bound for industrial, national laboratory, or academic careers, with special programmatic emphasis on participation by women and underrepresented minorities. True understanding of a catalytic system, such as the active site structure and reaction mechanism, is crucial for developing new, more sustainable, and atom-efficient catalytic processes. While typical small-molecule homogeneous catalysts have well-defined active sites, they are limited by thermal instability and product-catalyst separation challenges. Therefore most (~85%) industrial processes utilize heterogeneous catalysts, reflecting superior stability, recyclability, and ease of product-catalyst separation. Nevertheless, there is frequently limited understanding of heterogeneous catalyst active site structure, fraction of catalytically significant sites, and therefore, uncertainties in mechanism and how to optimize it for efficiency and selectivity. Between these domains lie single-site heterogeneous catalysts (SSHCs), combining well-defined molecular precursors with functional solid surfaces, ideally yielding isolated catalytic centers, characterizable by advancing physical techniques and theory. Nevertheless, how the catalyst-surface interaction modulates activity and selectivity are poorly understood, as is the scope of catalytic transformations possible. Marks’ and Bedzyk’s SSHC research effort is configured around two integrated exploratory, hypothesis-driven themes focus on two closely related SSHC systems having in common: earth-abundant high oxidation state transition metals tightly bound to catalytically functional earth-abundant supports, unusual reactivity patterns, shared catalyst evaluation methodologies, high percentages of catalytically significant sites, collaborative characterization by both conventional and unique emerging physical techniques at Northwestern and at Argonne and Ames DOE National Laboratories, and closely interfaced high-level theoretical/computational analysis of both systems. The goal is to understand catalyst-support structure-function-mechanism relationships in systems lying between homogeneous and heterogeneous catalysis. These are: 1) Earth-abundant green, positively charged transition metal catalysts on highly acidic surfaces. How do these catalysts recycle polyolefin plastics at unprecedented rates under very mild conditions? What useful can we learn from other metals and supports? 2) Earth-abundant, green molybdenum-oxygen catalysts on simple carbon surfaces. How do these catalysts produce hydrogen from agricultural alcohols? Fuels from agricultural and waste oils? Deconstruct PET bottles under very mild conditions? What useful can we learn from other SSHC metals and supports?

With the support of the DOE/BES Catalysis Science Program, Professors Tobin Marks and Michael Bedzyk of Northwestern University are discovering, characterizing, understanding, and optimizing for implementation, new catalytic reactions, and closely combining this research effort with educational outreach activities. Such catalytic processes are of great importance to the U.S. economy, and it is estimated that catalysis underlies approximately 35% of the U.S. GDP, producing coatings, fertilizers, fuels, plastics, pharmaceuticals, medical garments and equipment, and other chemicals on a vast scale. In the future, these important catalytic transformations must be more energy- and resource-efficient, non-toxic, non-polluting, and rely on low-cost, earth-abundant metals in more selective, sustainable, and economically competitive technologies. Tackling these important challenges will require a highly educated and diverse/inclusive National technical workforce, and US universities must play an essential role by broadly educating young scientists to attack global-scale problems, while carrying out forefront research across broad disciplinary fields. The projects funded by this award will involve a transdisciplinary, educationally rigorous mix of catalyst creation, catalyst evaluation, and understanding the pathways by which catalytic products are formed. These activities when combined with highly interactive research group environments will provide excellent training/mentoring for graduate, undergraduate, and postdoctoral students bound for industrial, national laboratory, or academic careers, with special programmatic emphasis on participation by women and underrepresented minorities.

True understanding of a catalytic system, such as the active site structure and reaction mechanism, is crucial for developing new, more sustainable, and atom-efficient catalytic processes. While typical small-molecule homogeneous catalysts have well-defined active sites, they are limited by thermal instability and product-catalyst separation challenges. Therefore most (~85%) industrial processes utilize heterogeneous catalysts, reflecting superior stability, recyclability, and ease of product-catalyst separation. Nevertheless, there is frequently limited understanding of heterogeneous catalyst active site structure, fraction of catalytically significant sites, and therefore, uncertainties in mechanism and how to optimize it for efficiency and selectivity. Between these domains lie single-site heterogeneous catalysts (SSHCs), combining well-defined molecular precursors with functional solid surfaces, ideally yielding isolated catalytic centers, characterizable by advancing physical techniques and theory. Nevertheless, how the catalyst-surface interaction modulates activity and selectivity are poorly understood, as is the scope of catalytic transformations possible.

Marks’ and Bedzyk’s SSHC research effort is configured around two integrated exploratory, hypothesis-driven themes focus on two closely related SSHC systems having in common: earth-abundant high oxidation state transition metals tightly bound to catalytically functional earth-abundant supports, unusual reactivity patterns, shared catalyst evaluation methodologies, high percentages of catalytically significant sites, collaborative characterization by both conventional and unique emerging physical techniques at Northwestern and at Argonne and Ames DOE National Laboratories, and closely interfaced high-level theoretical/computational analysis of both systems. The goal is to understand catalyst-support structure-function-mechanism relationships in systems lying between homogeneous and heterogeneous catalysis. These are: 1) Earth-abundant green, positively charged transition metal catalysts on highly acidic surfaces. How do these catalysts recycle polyolefin plastics at unprecedented rates under very mild conditions? What useful can we learn from other metals and supports? 2) Earth-abundant, green molybdenum-oxygen catalysts on simple carbon surfaces. How do these catalysts produce hydrogen from agricultural alcohols? Fuels from agricultural and waste oils? Deconstruct PET bottles under very mild conditions? What useful can we learn from other SSHC metals and supports?