CAREER: Rational Design of Nanoporous Catalysts for Carbonylation Reactions

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Annually, millions of tons of alcohols and carboxylic acids (used to create polymers, food additives, solvents, and pharmaceuticals) are produced industrially via catalytic carbonylation. Because this process makes use of expensive rare-metal catalysts and requires corrosive chemical agents to promote the desired reactions, the result is stringent and costly reactor designs, complex catalyst recycling schemes, and environmentally unfriendly waste streams. This project aims to discover effective porous solid-acid catalysts as a technologically and environmentally appealing alternative. Designing an optimal solid acid, however, is a challenging task, as there are hundreds of potential structures to choose from, each with unique, molecular-scale cavities that can stabilize or prevent different reactions. This project will develop computer models that allow us to make accurate predictions of which chemical reactions will take place, enabling a computationally efficient approach to catalyst design. These developments will positively impact manufacturing processes based on carbonylation chemistry, and also many other large-scale industrial processes that create the chemical products for our modern society. The research efforts are closely integrated with educational and outreach activities to serve our overarching goals of improving computational competency in the training of the next-generation workforce and promoting diversity and broadening participation of underrepresented students in STEM fields.Recent experimental work has demonstrated that nanoporous zeolites with 8-membered rings can potentially catalyze the carbonylation reaction with high selectivity, providing a compelling alternative to traditional rare metal-based catalyst systems. Despite the tantalizing potential, fundamentally important questions remain, including: What are the structural motifs that will make possible effective carbonylation of small methoxy groups versus larger carbocations in different zeolite architectures? How can acid-catalyzed side reactions be controlled by selectively suppressing undesired reactions? What are the mechanisms that determine the function of promoters and poisoners in these nanoporous solid acids? This research program will address these questions by developing and applying computational tools that integrate quantum chemical and forcefield-based molecular-scale simulations. The project will generate fundamental insights into confinement effects in nanoporous catalysts and will make possible the rational design of catalysts that target reactions selectively. A successful outcome may not only lead to industrially feasible, environmentally friendly solid acids for the synthesis of ethanol and acetic acid, but also provide general strategies for using solid acids in other organic syntheses and for controlling side reactions in many existing, large-scale solid acid catalytic processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.