Dissertation
INTEGRATING EXPERIMENTAL AND MOLECULAR MODELING APPROACHES FOR OPTIMIZED BIOCHAR PRODUCTION: ELUCIDATING PAH DISTRIBUTIONS, SECONDARY PYROLYSIS REACTIONS, SPECTRAL DATABASE DEVELOPMENT, AND SELECTIVE CARBONIZATION VIA ACID PRE-TREATMENTS AND PRESSURE
Washington State University
Doctor of Philosophy (PhD), Washington State University
05/2025
DOI:
https://doi.org/10.7273/000007469
Abstract
This thesis explored atomistic modeling, spectroscopic prediction, optimized carbonization methods, and secondary reaction mechanisms of cellulose to deepen our understanding of biochar's structural transformations and functionality. The study began by evaluating the effectiveness of large-scale atomistic models of lignocellulosic and carbonaceous materials, aiming to unravel the connections between production parameters, biochar behavior, molecular transformations, and pyrolysis kinetics, beyond conventional levoglucosan-based methodologies.
A computational framework was developed to generate realistic, large-scale (>10,000 atoms) atomistic representations of biochar. These models integrated experimental data and chemical information derived from computational methods such as density functional theory (DFT) and reactive molecular dynamics (MD) simulations. The resulting models accurately replicated structural and chemical characteristics, facilitating predictive biochar macroscopic properties and behavior simulations.
Further enhancing biochar characterization, the research combined DFT calculations with machine learning techniques to predict spectroscopic signatures, creating a comprehensive spectral database encompassing X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, infrared (IR), and nuclear magnetic resonance (NMR). The theoretical spectra obtained exhibited remarkable agreement with experimental data, significantly enhancing the reliability of molecular-level interpretations and spectroscopic predictions.
In addition, optimized carbonization strategies were investigated by assessing the effects of pressure and acid pretreatments on carbon yield and chemical properties. Both experimental and computational analyses revealed pathways to precisely control biochar composition, porosity, and chemical functionality, highlighting biochar’s potential for carbon storage and environmental remediation applications. These selective carbonization methods enhanced carbon retention by up to 78%.
Lastly, the thesis examined secondary reaction mechanisms underlying cellulose fast pyrolysis through reactive MD simulations. By identifying critical intermediates and reaction networks, this study provided novel insights into biochar formation, corroborated by experimental mass spectrometry and molecular characterization. Integrating computational and experimental approaches throughout the research provided a comprehensive understanding of biochar science, enabling rational design and enhanced performance in sustainable applications.
Metrics
13 File views/ downloads
38 Record Views
Details
- Title
- INTEGRATING EXPERIMENTAL AND MOLECULAR MODELING APPROACHES FOR OPTIMIZED BIOCHAR PRODUCTION
- Creators
- Valentina Sierra-Jimenez
- Contributors
- Manuel Garcia-Perez (Co-Chair)Farid Chejne (Co-Chair)Jonathan P. Mathews (Committee Member)Jonathan Male (Committee Member)Hanwui Lei (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Biological Systems Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 410
- Identifiers
- 99901221252501842
- Language
- English
- Resource Type
- Dissertation