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Redox Materials and Cycling Methods ...

Hill, Caroline M.

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Redox Materials and Cycling Methods for the Improvement of Solar Chemical-Looping Reforming of Methane.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Redox Materials and Cycling Methods for the Improvement of Solar Chemical-Looping Reforming of Methane./
Author:	Hill, Caroline M.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2023,
Description:	141 p.
Notes:	Source: Dissertations Abstracts International, Volume: 85-08, Section: B.
Contained By:	Dissertations Abstracts International85-08B.
Subject:	Alternative energy. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30318736
ISBN:	9798381697995

Redox Materials and Cycling Methods for the Improvement of Solar Chemical-Looping Reforming of Methane.
Hill, Caroline M.

Redox Materials and Cycling Methods for the Improvement of Solar Chemical-Looping Reforming of Methane. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 141 p.

Source: Dissertations Abstracts International, Volume: 85-08, Section: B.

Thesis (Ph.D.)--University of Florida, 2023.

This item must not be sold to any third party vendors.

Utilizing solar thermal energy to drive the chemical looping reforming of methane (CLRM) to produce syngas, a precursor to many commercial fuels, is a promising route to incorporating renewable energy into the transportation sector. This looping process consists of two steps: 1) the partial oxidation of methane (POM) via reduction of a metal oxide followed by 2) reoxidation of the metal oxide combined with CO2 and/or H2O splitting. In this work, various candidate metal oxides, with and without Ni catalytic decoration of the surface, were investigated for viability as CLRM oxygen exchange materials at low operating temperatures of 700-1100 ◦C using a thermogravimetric analyzer. The combination of Ni promoted CeO2 (Ni-CeO2) was chosen for further study based on high syngas selectivity and fast reaction rates at all temperatures studied. Direct comparison of CLRM in a packed bed reactor confirm overall performance, including methane conversion and total syngas production, with Ni-CeO2 at 700 - 800 ◦C was comparable to CeO2 when operating at higher temperatures of 1000-1100 ◦C. The only notable difference observed for Ni-CeO2 was a significant increase in carbon deposition during POM; however, the deposited carbon was readily oxidized in the subsequent CO2 splitting reaction and did not affect the overall H2/CO ratio. These results indicate promise for using Ni-CeO2 to generate syngas at the same rate as unpromoted CeO2 but at notably lower operating temperatures, thus improving the economic viability of this process. Methods of CLRM operation to improve syngas selectivity and feed gas conversion were also studied. A 1D thermodynamic model of POM in a packed-bed reactor was first developed to explore the evolution of product species and the spatial δ profile. Various starting δ profiles were also investigated to simulate incomplete oxidation of the packed bed. Results indicate that syngas selectivity increases with δexit and is independent δavg. This observation was confirmed by experimental investigation of CLRM with controlled reaction times in a packed bed reactor system. A new cycling method was then proposed and demonstrated: intermittent extended POM reaction times were introduced to periodically reestablish high δexit and maintain high syngas selectivity.

ISBN: 9798381697995Subjects--Topical Terms:

3436775
Alternative energy.
Subjects--Index Terms:

Kinetics

Redox Materials and Cycling Methods for the Improvement of Solar Chemical-Looping Reforming of Methane.
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245 1 0 $a Redox Materials and Cycling Methods for the Improvement of Solar Chemical-Looping Reforming of Methane.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2023
300 $a 141 p.
500 $a Source: Dissertations Abstracts International, Volume: 85-08, Section: B.
500 $a Advisor: Scheffe, Jonathan R.
502 $a Thesis (Ph.D.)--University of Florida, 2023.
506 $a This item must not be sold to any third party vendors.
520 $a Utilizing solar thermal energy to drive the chemical looping reforming of methane (CLRM) to produce syngas, a precursor to many commercial fuels, is a promising route to incorporating renewable energy into the transportation sector. This looping process consists of two steps: 1) the partial oxidation of methane (POM) via reduction of a metal oxide followed by 2) reoxidation of the metal oxide combined with CO2 and/or H2O splitting. In this work, various candidate metal oxides, with and without Ni catalytic decoration of the surface, were investigated for viability as CLRM oxygen exchange materials at low operating temperatures of 700-1100 ◦C using a thermogravimetric analyzer. The combination of Ni promoted CeO2 (Ni-CeO2) was chosen for further study based on high syngas selectivity and fast reaction rates at all temperatures studied. Direct comparison of CLRM in a packed bed reactor confirm overall performance, including methane conversion and total syngas production, with Ni-CeO2 at 700 - 800 ◦C was comparable to CeO2 when operating at higher temperatures of 1000-1100 ◦C. The only notable difference observed for Ni-CeO2 was a significant increase in carbon deposition during POM; however, the deposited carbon was readily oxidized in the subsequent CO2 splitting reaction and did not affect the overall H2/CO ratio. These results indicate promise for using Ni-CeO2 to generate syngas at the same rate as unpromoted CeO2 but at notably lower operating temperatures, thus improving the economic viability of this process. Methods of CLRM operation to improve syngas selectivity and feed gas conversion were also studied. A 1D thermodynamic model of POM in a packed-bed reactor was first developed to explore the evolution of product species and the spatial δ profile. Various starting δ profiles were also investigated to simulate incomplete oxidation of the packed bed. Results indicate that syngas selectivity increases with δexit and is independent δavg. This observation was confirmed by experimental investigation of CLRM with controlled reaction times in a packed bed reactor system. A new cycling method was then proposed and demonstrated: intermittent extended POM reaction times were introduced to periodically reestablish high δexit and maintain high syngas selectivity.
590 $a School code: 0070.
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650 4 $a Chemistry. $3 516420
650 4 $a Engineering. $3 586835
650 4 $a Materials science. $3 543314
650 4 $a Thermodynamics. $3 517304
653 $a Kinetics
653 $a Methane reforming
653 $a Metal oxides
653 $a Solar energy
653 $a Syngas production
653 $a Chemical looping
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690 $a 0794
690 $a 0537
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690 $a 0485
710 2 $a University of Florida. $b Mechanical Engineering. $3 3350759
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