Author ORCID Identifier

https://orcid.org/0000-0003-1971-9018

Semester

Fall

Date of Graduation

2022

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Chemical and Biomedical Engineering

Committee Chair

Debangsu Bhattacharyya

Committee Co-Chair

Fernando Lima

Committee Member

Fernando Lima

Committee Member

Jianli Hu

Committee Member

David Mebane

Committee Member

Benjamin Omell

Abstract

Post-combustion capture is one of the leading technologies for CO2 abatement from anthropogenic sources which have contributed significantly to the rise of atmospheric greenhouse gases. Specifically, solvent-based capture post-combustion processes are the industry standard but can suffer drawbacks such as high energy penalties and corrosion. In this work, two possible improvements are investigated which have been recently proposed in the literature. The first is aqueous ammonia as a capture solvent which has been shown to have several advantages including, but not limited to, a lower regeneration energy. The second is a novel solid sorbent, an amine-appended metal-organic framework (MOF). The MOF exhibits several promising attributes, namely, a step-shaped adsorption isotherm which leads to lower working capacities and lower regeneration energies when compared to traditional solid sorbents. The overall goal of this work is to develop rigorous mathematical models which can be used for process design and economic evaluation of these technologies.

First, an integrated mass transfer model is developed for the chilled ammonia process (CAP). This model is developed using a simultaneous regression approach that has been recently proposed in the literature with parameter estimation performed using data from a pilot plant source and wetted-wall column. The optimally estimated parameters are shown to have a lower prediction error to validation data than parameters found in literature. The integrated mass transfer model is then used to develop a model for a novel chilled ammonia process. The process includes a NH3 abatement system which utilizes a reverse osmosis membrane to aid in separation and reduce the energy penalty. Simulation of the process shows that the membrane can significantly reduce the energy requirement of the reboiler, condenser, and cooler in the abatement section. Uncertainty of the estimated mass transfer parameters is quantified using a fully Bayesian approach which is demonstrated to show a significant reduction in the prediction uncertainty of key process indicators.

Second, isotherm and kinetic models are developed for amine-appended MOFs, dmpn-Mg2(dobpdc) and Mg2(dobpdc)(3-4-3). The step-shaped adsorption isotherms exhibited by these MOFs present a modeling challenge since many of the traditional isotherm models are unable to capture step transitions. Three isotherm models are examined in this work, a weighted dual-site Langmuir model found in literature, a dual-site Sips model developed in this work, and an extended weighted Langmuir model also developed in this work. Parameter estimation is performed using available isotherm data and it is shown that the models are able to predict the CO2 adsorption data well. A kinetic model is then developed using a linear driving force for mass transfer which does an excellent job at predicting time dependent TGA data. An additional goal of this work is development of a chemistry-based model for functionalized solid sorbents that aims to capture the underlying adsorption reaction mechanisms which are not typically considered in solid sorbent modeling. As part of this model, optimal reaction set selection is performed since the reaction pathways for dmpn-Mg2(dobpdc) are still relatively unknown. Parameter estimation is performed, and it is found that the chemistry-based model significantly outperforms the Sips isotherm model with regards to prediction error and other model building criteria. To aid in the evaluation of the commercial feasibility of the MOF, equation-oriented mathematical models for a fixed bed contactor and moving bed contactor are developed. The contactors are then to simulate industrial scale CO2 capture process for coal based and NGCC based flue gas. Using developed cost models, techno-economic analysis and optimization of these processes is then performed and it is found that efficient thermal management can make these MOFs viable alternatives for CO2 capture processes.

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