Candidate:

Mona Abdelgaid

Title:

Catalyst Design for Dehydrogenation of Light Alkanes to Olefins

Abstract:

Light olefins are versatile building blocks to produce petrochemicals, plastics, and polymers. Currently, there is a rapidly increasing gap between global demand and supply for olefins. The abundance of light alkanes from shale gas reserves offers an excellent opportunity for “on-purpose” production of light olefins through catalytic nonoxidative dehydrogenation (DH) of alkanes. The discovery of active catalysts plays a critical role in reducing the energy input required in DH processes. Heterogeneous catalysts, such as metal oxides and nitrides, can selectively activate the C–H bonds of alkanes due to their characteristic Lewis acidity (metal) and basicity (oxygen or nitrogen). However, discovering efficient DH catalysts has traditionally relied on trial-and-error experimentation. Alternatively, developing structure-activity relationships (SARs) based on first-principles calculations can accelerate the screening of active and selective catalysts for the production of olefins. 

This work developed and applied DH SARs for the discovery of active and selective DH catalysts. First, we provided mechanistic insights into alkane DH reactions on pristine and gallium-doped γ-Al₂O₃ using Density Functional Theory (DFT) and developed SARs based on fundamental properties of the catalyst and reacting hydrocarbons. Following an initial catalyst screening approach followed by detailed DFT calculations and microkinetic modeling, we revealed pristine aluminum nitride (AlN) as an efficient DH catalyst. Lastly, we employed heterometal doping as a strategy to enhance the DH performance of pristine AlN. We showcased that Zn-doped AlN exhibits high DH activity and olefin selectivity compared to pristine AlN and other oxides reported in literature. Importantly, we elucidated very complex hydrocarbon DH mechanisms on novel, previously untested AlN catalysts. Overall, this dissertation provides important insights into designing highly active DH catalysts for industrial applications, while revealing rich information on DH mechanisms.

Committee Chair:

Dr. Giannis Mpourmpakis

Department of Chemical and Petroleum Engineering

University of Pittsburgh

Committee Members:

Dr. Götz Veser

Department of Chemical and Petroleum Engineering

University of Pittsburgh

Dr. Mohammad Masnadi Shirazinejad

Department of Chemical and Petroleum Engineering

University of Pittsburgh

Dr. Peng Liu

Department of Chemistry

University of Pittsburgh