Alexandria Digital Research Library

Understanding and Controlling Light Alkane Reactivity on Metal Oxides : Optimization Through Doping

Author:
Derk, Alan Richard
Degree Grantor:
University of California, Santa Barbara. Chemical Engineering
Degree Supervisor:
Eric W. McFarland and Horia Metiu
Place of Publication:
[Santa Barbara, Calif.]
Publisher:
University of California, Santa Barbara
Creation Date:
2015
Issued Date:
2015
Topics:
Chemical engineering
Genres:
Dissertations, Academic and Online resources
Dissertation:
Ph.D.--University of California, Santa Barbara, 2015
Description:

Metal oxide catalysts have numerous industrial applications and have garnered research attention. Although oxides catalyze many important reactions, their yields to products are too low to be of economic value due to low conversion and/or low selectivity. For example, some oxides can catalyze the conversion of methane to intermediates or products that are liquefiable at yields no higher than 30%. With improved yield, such a process could help reduce the trillions of cubic feet of natural gas flared every year, saving billions of dollars and millions of tonnes of greenhouse gases. To this end, one goal of this work is to understand and improve the catalytic activity of oxides by substituting a small fraction of the cations of a "host oxide" with a different cation, a "dopant." This substitution disrupts chemical bonding at the surface of the host oxide, which can improve reactant and lattice oxygen activation where the reaction takes place. Another goal of this work is to combine catalysts with metal oxides reactants to improve thermodynamic limitations. Outstanding challenges for the study of doped metal oxide catalysts include (1) selection of dopants to ix synthesize within a host oxide and (2) understanding the nature of the surface of the doped oxide during reaction.

Herein, strongly coupled theoretical calculations and experimental techniques are employed to design, synthesize, characterize, and catalytically analyze doped oxide catalysts for the optimization of light alkane conversion processes. Density Functional Theory calculations are used to predict different energies believed to be involved in the reaction mechanism. These parameters offer valuable suggestions on which dopants may perform with highest yield and activity and why. Synthesis is accomplished using a combination of wet chemical techniques, suited specifically for the preparation of doped (rather than supported or mixed) metal oxide catalysts of high surface area and high reactivity. Characterization is paramount in any doped-oxide investigation to determine if the catalyst under reaction conditions is truly doped or merely small clusters of supported catalyst. With that goal, diffraction, X-ray, electron microscopies, infrared spectroscopy, and chemical probes are used to determine the nanoscopic nature of the catalysts. Additional novel measurement techniques, such as transient oxidation reaction spectroscopy, determined the nature of the active site's oxidation state.

Physical Description:
1 online resource (181 pages)
Format:
Text
Collection(s):
UCSB electronic theses and dissertations
ARK:
ark:/48907/f3k935qs
ISBN:
9781339084046
Catalog System Number:
990045715540203776
Rights:
Inc.icon only.dark In Copyright
Copyright Holder:
Alan Derk
File Description
Access: Public access
Derk_ucsb_0035D_12559.pdf pdf (Portable Document Format)