CaltechTHESIS
  A Caltech Library Service

From Quantum Mechanics to Experimental Observables: Computational Investigations of Energy-Related Heterogeneous Catalysts

Citation

Qian, Jin (2019) From Quantum Mechanics to Experimental Observables: Computational Investigations of Energy-Related Heterogeneous Catalysts. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/SPEJ-5X35. http://resolver.caltech.edu/CaltechTHESIS:12072018-215548214

Abstract

One of the most severe challenges in this decade is assuring more secure, more efficient, cleaner, and more sustainable energy to power our world. This work takes a catalytic approach to help overcome this challenge.

The Haber Bosch process is one of the towering achievements of industrial chemistry. It consumes a huge amount of energy due to the high temperature and high pressure reaction condition, and in turn, has enabled us to produce enough nitrogen fertilizer to feed the current world population. An essential goal of present research is therefore to dramatically reduce Haber Bosch energy cost by improving the catalytic performance of the presently used Fe-based heterogeneous catalysts. We use quantum mechanics (QM) and kinetic Monte Carlo (kMC) to predict reaction mechanisms and kinetics for NH3 synthesis on Fe(111) – the best Fe single crystal surface for NH3 synthesis. We find excellent agreement with a predicted turnover frequency (TOF) of 17.7 sec-1 per 2x2 site (5.3 x 10-9 moles/cm2/sec) compared to TOF=10 sec-1 per site from experiment, and we further predict that top-layer Co doping leads to an acceleration by a factor of 2.3 in reaction rates of ammonia synthesis.

Compared to the industrialized Haber Bosch reaction, renewable energy technologies are still in their infancy with a great deal of questions unanswered, as well as a lot of barriers to overcome. Here we report our atomistic understanding of how CO2 and H2O molecules adsorb on the catalyst surface and interact to initiate CO2 dissociation and subsequent product formation. Using synergistic experimental and theoretical analyses, we show that Cu and Ag operate entirely differently for the first step of activating CO2. We develop a method of predicting the ambient pressure XPS spectrum in an ab-initio multiscale fashion: from electronic structure, to atomic picture, to chemical reaction network (CRN), and eventually to the experimental observable. We bridge both the qualitative and quantitative gap from quantum mechanics to XPS, and demonstrate our approach by decoding the initial H2O adsorption and complex formation on Ag(111) surface, which we encourage to be the new standard protocol in this field.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Heterogeneous Catalysis; Quantum Mechanics; Kinetics; Haber Bosch; CO2 reduction
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Materials Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Goddard, William A., III
Thesis Committee:
  • Fultz, Brent T. (chair)
  • Atwater, Harry Albert
  • Soriaga, Manuel P.
  • Goddard, William A., III
Defense Date:8 January 2019
Record Number:CaltechTHESIS:03142019-171751551
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:12072018-215548214
DOI:10.7907/SPEJ-5X35
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/jacs.7b13409DOIArticle adapted for ch.2
https://doi.org/10.1016/j.jcat.2019.01.001DOIArticle adapted for ch.3
ORCID:
AuthorORCID
Qian, Jin0000-0002-0162-0477
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11429
Collection:CaltechTHESIS
Deposited By: Jin Qian
Deposited On:20 Mar 2019 21:06
Last Modified:27 Mar 2019 16:18

Thesis Files

[img]
Preview
PDF - Final Version
See Usage Policy.

6Mb

Repository Staff Only: item control page