SUBJECT: Ph.D. Proposal Presentation
BY: Nhu Nguyen
TIME: Wednesday, May 17, 2023, 3:30 p.m.
PLACE: Boggs, 3-47
TITLE: Renewable solar thermochemical NH3 production: Materials characterization and reactor modeling
COMMITTEE: Dr. Peter G. Loutzenhiser, Chair (ME)
Dr. Marta Hatzell (ME)
Mark D. Losego (MSE)
Dr. Satish Kumar (ME)
Dr. Andrea Ambrosini (Sandia National Lab)


Concentrated solar power is an effective and carbon-neutral energy source. Investigation of utilizing concentrated solar thermal energy to produce chemical commodities and examining effective ways to transfer and store thermal energy are crucial to the effort to decarbonize industry. NH3 production from air and H2 via a two-stage solar thermochemical cycle without CO2 emission is considered: (1) air separation to produce N2 and (2) NH3 synthesis from H2 and N2. A and B-site substituted and unsubstituted SrFeO3 samples used for air separation are screened via thermogravimetry to characterize oxygen capacity and chemical stability under elevated temperatures up to 1300 °C, under various oxygen partial pressure and in the presence of common impurities such as CO2 and H2O(v). Rate limiting mechanisms are investigated for reduction/oxidation reactions using a combination of isothermal and non-isothermal thermogravimetry. Fe-substituted and unsubstituted Co3Mo3N to facilitate NH3 synthesis are characterized to develop a model predicting material reduction/nitridation extents under various nitrogen partial pressure. Produced NH3 is quantified using in-situ liquid conductivity measurements coupled with mass spectrometry. Material characterization results for perovskites oxides are used as inputs for investigation of a packed particle bed reactor design for CSP air separation applications at intermediate temperature below 800 °C. Additional mechanical properties of particles used as heat transfer and storage media are measured at temperatures from 600 to 800 °C for application in concentrated solar thermal energy transfer and storage. These mechanical properties are utilized to investigate pseudo-viscous fluid properties of dense granular flow at various elevated temperatures.