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Nanocomposite Catalytic Materials for Clean Energy Processes

Sanders, Thomas James (2008) Nanocomposite Catalytic Materials for Clean Energy Processes. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Nanomaterials have gained much attention as catalysts since the discovery of exceptional CO oxidation activity of nanoscale gold by Haruta. However, many studies avoid testing nanomaterials at the high-temperatures relevant to reactions of interest for the production of clean energy (T > 700°C). The generally poor thermal stability of catalytically active noble metals has thus far prevented significant progress in this area. We have recently overcome the poor thermal stability of nanoparticles by synthesizing a platinum barium-hexaaluminate (Pt-BHA) nanocomposite which combines the high activity of noble metal nanoparticles with the thermal stability of hexaaluminates. This Pt-BHA nanocomposite demonstrates excellent activity, selectivity, and long-term stability in CPOM. Pt-BHA is anchored onto a variety of support structures in order to improve the accessibility, safety, and reactivity of the nanocatalyst. Silica felts prove to be particularly amenable to this supporting procedure, with the resulting supported nanocatalyst proving to be as active and stable for CPOM as its unsupported counterpart. Various pre-treatment conditions are evaluated to determine their effectiveness in removing residual surfactant from the active nanoscale platinum particles. The size of these particles is measured across a wide temperature range, and the resulting "plateau" of stability from 600-900°C can be linked to a particle caging effect due to the structure of the supporting ceramic framework. The nanocomposites are used to catalyze the combustion of a dilute methane stream, and the results indicate enhanced activity for both Pt-BHA as well as ceria-doped BHA, as well as an absence of internal mass transfer limitations at the conditions tested. In water-gas shift reaction, nanocomposite Pt-BHA shows stability during prolonged WGS reaction and no signs of deactivation during start-up/shut-down of the reactor.The chemical and thermal stability, low molecular weight, and wealth of literature on the formation of mesoporous silica materials motivated investigations of nanocomposite silica catalysts. High surface area silicas are synthesized via sol-gel methods, and the addition of metal-salts lead to the formation of stable nanocomposite Ni- and Fe- silicates.The results of these investigations have increased the fundamental understanding and improved the applicability of nanocatalysts for clean energy applications.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Sanders, Thomas Jamestomsand@gmail.com
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairVeser, Goetzgveser@pitt.eduGVESER
Committee MemberMiller, James Bjbmiller@andrew.cmu.edu
Committee MemberEnick, Robertenick@engr.pitt.eduRME
Committee MemberLittle, Steven Rslittle@engr.pitt.eduSRLITTLE
Date: 8 September 2008
Date Type: Completion
Defense Date: 25 April 2008
Approval Date: 8 September 2008
Submission Date: 7 May 2008
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Chemical Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: heterogeneous catalysis; hexaaluminate; microemulsion-templated synthesis; partial oxidation of methane; reaction; sintering resistance; sol-gel
Other ID: http://etd.library.pitt.edu/ETD/available/etd-05072008-114720/, etd-05072008-114720
Date Deposited: 10 Nov 2011 19:44
Last Modified: 15 Nov 2016 13:43
URI: http://d-scholarship.pitt.edu/id/eprint/7821

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