Author ORCID Identifier

https://orcid.org/0000-0002-3635-9934

Semester

Spring

Date of Graduation

2023

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Chemical and Biomedical Engineering

Committee Chair

Jianli Hu

Committee Member

Debangsu Battacharyya

Committee Member

Charter Stinespring

Committee Member

Xueyan Song

Committee Member

Christina Wildfire

Abstract

Ammonia is critical to supporting human life on earth because of its use as fertilizer. The Haber-Bosch process to produce ammonia has been practiced for over 100 years. This process operates at high pressure and temperature to overcome the thermodynamic and kinetic limitations of the ammonia synthesis reaction thus researchers have tried to overcome it for decades. At present this process represents 1% of global energy usage and 2.5% of global CO2 emissions. The proposed chemical looping ammonia synthesis approach seeks to reduce the environmental impact of this critical process and to elucidate microwave-catalytic principles.

This research aims to reduce the operating conditions of ammonia synthesis and, critically, to avoid the thermodynamic limitation on ammonia synthesis by operating in a cyclical manner. The cyclical nature of this process also lends itself to use with intermittent and geographically distant renewable energy sources. Ammonia is a promising energy storage vector for the hydrogen economy and the decentralized production of ammonia for agriculture and energy storage is an attractive prospect. Special materials must be developed and characterized to operate under these conditions and fundamentals of these systems are established.

Nitrogen storage materials were considered in model chemical looping cycles to study their productivity and deactivation. These materials included earth abundant transition metals such as Fe, CoMo, and Mn. Rapid thermal cycling achieved using microwave-active catalysts, and microwave-plasma is used to pre-activate the stable N2 molecule. Microwave-matter interactions were analyzed to develop better catalysts, and well-established materials were characterized by kinetic and time on stream results are reported.

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