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Catalytic partial oxidation of methane over nickel and ruthenium based catalysts for GTL applications
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.ORCID iD: 0000-0002-3793-1197
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The Gas to Liquids (GTL) process is an important alternative for monetizing natural gas through the production of long-chain liquid hydrocarbons, e.g. diesel fuel. The GTL process involves three main steps: synthesis gas production to obtain H2 and CO, Fischer-Tropsch synthesis to obtain a synthetic crude oil, and upgrading/refining to obtain final products. Since the synthesis gas production is the most expensive step, there is great interest in optimizing and exploring new routes for syngas production.

This thesis focuses on the conversion of methane, the main component of natural gas, into synthesis gas by catalytic partial oxidation (CPO). Several aspects of the CPO reaction in the context of the GTL technology are discussed. The work contributes to an increased knowledge concerning utilizing a CPO reactor as pre-reformer in the synthesis gas production process as well as the influence of catalyst properties and composition on the catalytic behavior when using nickel and ruthenium-based catalysts in the CPO reaction.

The thesis is a summary of five publications. The first two publications (Papers I and II) review the current status of both the GTL technology and the catalytic partial oxidation of methane. Paper III analyzes a process configuration comprising of a CPO pre-reformer followed by an autothermal reforming (ATR) reactor using a thermodynamic equilibrium approach. It was found that a proper manipulation of the process conditions is needed to obtain a suitable synthesis gas for GTL applications simultaneously of minimizing the risk of carbon formation in the CPO reactor; the operation of the CPO reactor demanded low O2/CH4 and H2O/CH4 feed molar ratios. Accordingly, in paper IV, the partial oxidation of methane at low O2/CH4 and H2O/CH4 ratios is investigated over nickel and ruthenium catalysts supported on MgO/MgAl2O4 and compared with a commercial nickel-based catalyst. The extent or impact of the combustion and reforming reactions along the catalytic bed are substantially influenced by catalyst properties and composition. Deactivation by carbon formation is also discussed; ruthenium-containing catalysts might positively overcome carbon formation. To gain greater insight concerning the influence of the catalyst composition and properties on carbon formation, a set of nickel and bimetallic nickel-ruthenium catalysts, supported on α-Al2O3, γ-Al2O3 and MgO/MgAl2O4, is tested in the CH4 decomposition reaction in Paper V. For these catalysts, the resistance towards carbon formation is mainly correlated with the nickel particle size. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , xi, 83 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:63
Keyword [en]
Catalytic partial oxidation, carbon formation, GTL, nickel, ruthenium, synthesis gas, thermodynamic equilibrium.
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-176424ISBN: 978-91-7595-753-1 (print)OAI: oai:DiVA.org:kth-176424DiVA: diva2:866844
Public defence
2015-11-27, K1, Teknikringen 56, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20151105

Available from: 2015-11-04 Created: 2015-11-03 Last updated: 2015-11-04Bibliographically approved
List of papers
1. Gas to liquids: A technology for natural gas industrialization in Bolivia
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2010 (English)In: Journal of Natural Gas Science and Engineering, ISSN 1875-5100, E-ISSN 2212-3865, Vol. 2, no 5, 222-228 p.Article in journal (Refereed) Published
Abstract [en]

Gas-to-Liquids (GTL) technology converts natural gas, through Fischer-Tropsch synthesis, into liquid and ultra-clean hydrocarbons such as light oils, kerosene, naphtha, diesel, and wax. Bolivia has natural gas reserves that reach 48.7 trillion cubic feet and produces nearly 40.0 million cubic meters per day, from which, around 88% are exported to Brazil and Argentina. In spite of these considerable amounts of natural gas reserves and production, the country experiences a shortage of diesel which cannot be solved using conventional refining processes due the light nature of its crude oil. Thus, the GTL process seems to be a promising solution for Bolivia's diesel problems, at the same time that its natural gas reserves could be monetized. Although GTL can be considered as a well proven and developed technology, there are several aspects along the main processing steps (synthesis gas generation, Fischer-Tropsch synthesis, and product upgrading) to be considered at the time of implementing a GTL plant. The aim of this paper is to give an overall view of some relevant issues related to Gas-to-Liquids technology as an option for natural gas industrialization in Bolivia, and also to provide a landscape of Bolivian natural gas industry.

Keyword
Bolivian natural gas, Gas-to-Liquids (GTL), Synthesis Gas, Fischer-Tropsch, Hydrocracking
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-138474 (URN)10.1016/j.jngse.2010.10.001 (DOI)000208679200003 ()2-s2.0-78049504771 (Scopus ID)
Note

QC 20140109

Available from: 2014-01-09 Created: 2013-12-19 Last updated: 2017-12-06Bibliographically approved
2. Recent developments and achievements in partial oxidation of methane with and without addition of steam
Open this publication in new window or tab >>Recent developments and achievements in partial oxidation of methane with and without addition of steam
2011 (English)In: Catalysis / [ed] James J. Spivey, Royal Society of Chemistry, 2011, 23, 50-95 p.Chapter in book (Refereed)
Abstract [en]

The latest works on catalytic partial oxidation of methane (CPO) have beenconsidered and reviewed to give an updated frame of the state of the art inthis topic. Papers published since 2008 have been considered, dealing withthe process both without and with addition of steam. Particular attentionwas dedicated to Ni and Rh, that are the most used metals. The mechanismfollowed by the reaction was also considered as well as new and promisingtechnologies such as SOFCs, membrane reactors and plasma systems.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2011 Edition: 23
Series
Catalysis
Keyword
CPO, steam, syngas, ATR, methane, H2
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-88872 (URN)10.1039/9781849732772-00050 (DOI)2-s2.0-84860250151 (Scopus ID)978-1-84973-277-2 (ISBN)
Note
QC 20120222Available from: 2012-02-14 Created: 2012-02-14 Last updated: 2015-11-04Bibliographically approved
3. Synthesis gas production for GTL applications: Thermodynamic equilibrium approach and potential for carbon formation in a catalytic partial oxidation pre-reformer
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2014 (English)In: Journal of Natural Gas Science and Engineering, ISSN 1875-5100, E-ISSN 2212-3865, Vol. 20, 175-183 p.Article in journal (Refereed) Published
Abstract [en]

The present work is focused on synthesis gas production for Gas to Liquids (GTL.) applications. A thermodynamic equilibrium approach has been chosen in order to address the methane reforming processes in presence of steam and oxygen (i.e. autothermal reforming "ATR" and catalytic partial oxidation "CPO"). The effect of operational variables on the performance of the reforming units has been analyzed at conditions typical for GTL processes. Also, the performance of a synthesis gas generation unit (SGU) comprising a CPO pre-reformer followed by an ATR reactor has been investigated. The potential for carbon formation in the CPO pre-reformer has been evaluated by applying the "equilibrated gas principle". Our results show that synthesis gas production can be strongly influenced by changes in operating variables such as the steam-to-carbon (S/C) and the oxygen-to-carbon (O-2/C) ratios, recycled gas (tail gas) compositions, and operating pressures and temperatures; however, effective operation of the SGU (CPO + ATR) requires an correct combination of these variables in order to accomplish the synthesis gas requirements of the Fischer-Tropsch synthesis. Likewise, it is shown that the risk of carbon formation in the CPO reactor can be reduced or even eliminated by a proper manipulation and combination of such variables.

Place, publisher, year, edition, pages
Elsevier, 2014
Keyword
Catalytic partial oxidation, Equilibrated gas principle, GTL applications, Synthesis gas production, Thermodynamic equilibrium
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-154767 (URN)10.1016/j.jngse.2014.06.021 (DOI)000342258100021 ()2-s2.0-84904318902 (Scopus ID)
Funder
Sida - Swedish International Development Cooperation Agency
Note

QC 20141104

Available from: 2014-11-04 Created: 2014-10-27 Last updated: 2017-12-05Bibliographically approved
4. Catalytic partial oxidation of methane over nickel and ruthenium based catalysts under low O2/CH4 ratios and with addition of steam
Open this publication in new window or tab >>Catalytic partial oxidation of methane over nickel and ruthenium based catalysts under low O2/CH4 ratios and with addition of steam
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2015 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 153, 192-201 p.Article in journal (Refereed) Published
Abstract [en]

Catalytic partial oxidation (CPO) of methane to synthesis gas at low O2/CH4 ratios and in the presence of steam was investigated over nickel and ruthenium catalysts supported on hydrotalcite-derived materials. The influence of catalyst properties and composition on activity, temperature profile and deactivation by carbon formation was examined. All catalyst presented high methane conversions, close to the values predicted by thermodynamic equilibrium and such conversions increased in proportion to the metal surface of the catalyst tested. The temperature profiles at O2/CH4 = 0.2 and H2O/CH4 = 0.3 and a constant exit temperature of 700 °C varied depending on the catalyst type; it was possible to examine catalyst deactivation from the change in the shape of the profile of each catalyst. Since the O2/CH4 and H2O/CH4 ratios were low, the risk or potential for carbon formation was thermodynamically favorable along the entire catalytic bed; however, this potential was qualitatively higher when the temperature profile of the catalyst presented a pronounced maximum peak at the inlet of the reactor. During catalytic reaction tests and methane decomposition experiments, the ruthenium catalyst did not formed appreciable amounts of carbon while a bimetallic catalyst (Ni and Ru) form only small amounts (in comparison with the nickel catalysts). For the ruthenium catalyst, a higher O2/CH4 ratio favored conversions closer to the equilibrium value. The observations presented in this work indicate that during the CPO of methane, at low O2/CH4 ratios and in the presence of steam, the catalyst properties and composition will have a substantial influence on the extent of the combustion and reforming reactions along the catalytic bed. This will in turn define the temperature profile, and therefore the risk or potential for carbon formation; this risk might effectively be overcome by the use of ruthenium-containing catalysts.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Carbon formation, Nickel, Partial oxidation of methane, Ruthenium, Synthesis gas, Carbon, Catalysis, Catalyst activity, Catalyst deactivation, Catalytic oxidation, Catalytic reforming, Methane, Oxidation, Reforming reactions, Steam reforming, Synthesis (chemical), Temperature, Temperature control, Bimetallic catalysts, Catalytic partial oxidation, Catalytic partial oxidation of methane, Methane decomposition, Ruthenium based catalysts, Thermodynamic equilibria, Catalysts
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-167689 (URN)10.1016/j.fuel.2015.03.009 (DOI)000352800800024 ()2-s2.0-84925353352 (Scopus ID)
Funder
Sida - Swedish International Development Cooperation Agency
Note

QC 20150602

Available from: 2015-06-02 Created: 2015-05-22 Last updated: 2017-12-04Bibliographically approved
5. Methane partial oxidation and methane decomposition over Ni andNi-Ru supported catalysts for synthesis gas production
Open this publication in new window or tab >>Methane partial oxidation and methane decomposition over Ni andNi-Ru supported catalysts for synthesis gas production
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Nickel and nickel-ruthenium based catalysts were compared in the catalytic partial oxidation (CPO) of methane and in the equilibrium of the methane decomposition reaction. A hydrotalcite-derived material as well as α- Al2O3 and γ-Al2O3 were used as catalyst supports. The catalysts were characterized by H2 chemisorption, N2 physisorption, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO) and transmission electron microscopy (TEM). Catalyst properties and composition influenced the catalytic performance during partial oxidation (i.e. activity and temperature profiles). During methane decomposition equilibrium tests, all catalysts presented smaller equilibrium constants than those calculated on the basis of graphite; the deviation from graphite data was mainly associated with maximum nickel particle size (for both Ni and bimetallic Ni-Ru supported catalysts). Among all catalysts, the bimetallic Ni-Ru catalyst supported on hydrotalcite-derived material showed an interesting enhanced behavior; however, resistance towards catalyst deactivation, by mechanisms different than carbon formation, still needs to be improved. 

Keyword
carbon formation, methane decomposition, nickel, partial oxidation of methane, ruthenium, synthesis gas
National Category
Chemical Process Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-176409 (URN)
Note

QS 2015

Available from: 2015-11-03 Created: 2015-11-03 Last updated: 2015-11-04Bibliographically approved

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