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Hydrogen generation from n-tetradecane, low-sulfur and Fischer-Tropsch diesel over Rh supported on alumina doped with ceria/lanthana
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
Volvo Technology.
Volvo Technology.
Volvo Technology.
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2011 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 164, no 1, 190-197 p.Article in journal (Refereed) Published
Abstract [en]

The present study demonstrates the use of rhodium-based monolithic catalyst for onboard reforming of diesel fuels. Experimental results from hydrogen generation of n-tetradecane, low-sulfur and Fischer-Tropsch diesel, via autothermal reforming (ATR), were acquired with a catalyst consisting of 3 wt% Rh supported on alumina doped with Ce/La. The catalyst was prepared by impregnation using the incipient wetness technique, and deposited onto a 400 cpsi cordierite monolith. Furthermore, the catalyst was tested over ranges of oxygen-to-carbon and water-to-carbon feed ratios, both in a bench-scale and a full-scale reactor. Fresh powder samples of the catalyst were characterized by XRD, N(2)-BET, H(2) chemisorption, H(2)-TPR and XPS analyses. The activity results showed that high fuel conversions and hydrogen production could be achieved with 3 wt% Rh for all fuels. Furthermore, the highest formation of CO and C(2)H(4) was found in the product gas stream from the low-sulfur diesel. In addition, partial oxidation and steam reforming reactions were identified by closely studying the distribution of the analyzed product gas composition and the temperature measurements. The characterization results showed the presence of finely dispersed Rh particles in the support. Furthermore, bulk and surface rhodium oxides were detected, which have been suggested to be one of the major active phases for ATR of diesel. Bulk and surface cerium oxides (CeO(2)) and surface La in the dispersed phase were also found to be present in the catalyst composition. These promoters are believed to improve the catalyst activity and durability.

Place, publisher, year, edition, pages
2011. Vol. 164, no 1, 190-197 p.
Keyword [en]
Autothermal reforming, Ceria, Cordierite monolith, Diesel, Lanthana, Rhodium
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-32507DOI: 10.1016/j.cattod.2010.10.019ISI: 000289716300035Scopus ID: 2-s2.0-79955064483OAI: oai:DiVA.org:kth-32507DiVA: diva2:410916
Note
QC 20110415Available from: 2011-04-15 Created: 2011-04-15 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Rhodium diesel-reforming catalysts for fuel cell applications
Open this publication in new window or tab >>Rhodium diesel-reforming catalysts for fuel cell applications
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Heavy-duty diesel truck engines are routinely idled at standstill to provide cab heating or air conditioning, and in addition to supply electricity to comfort units such as radio and TV. Idling is an inefficient and unfavorable process resulting in increased fuel consumption, increased emissions, shortened engine life, impaired driver rest and health, and elevated noise. Hydrogen-fueled, polymer-electrolyte fuel-cell auxiliary power unit (PEFC-APU) as a silent external power supply, working independently of the main engine, is proposed as viable solution for better fuel economy and abatement of idling emissions. In a diesel PEFC-APU, the hydrogen storage problem is circumvented as hydrogen can be generated onboard from diesel by using a catalytic reformer. In order to make catalytic diesel PEFC-APU systems viable for commercialization research is still needed. Two key areas are the development of reforming catalyst and reformer design, which both are the scope of this thesis. For diesel-reforming catalysts, low loadings of Rh and RhPt alloys have proven to exhibit excellent reforming and hydrogen selectivity properties. For the development of a stable reforming catalyst, more studies have to be conducted in order to find suitable promoters and support materials to optimize and sustain the long-term performance of the Rh catalyst. The next step will be full-scale tests carried out at realistic operating conditions in order to fully comprehend the overall reforming process and to validate promising Rh catalysts. This thesis can be divided into two parts; the first part addresses the development of catalysts in the form of washcoated cordierite monoliths for autothermal reforming (ATR) of diesel. A variety of catalyst compositions were developed containing Rh or RhPt as active metals, CeO2, La2O3, MgO, Y2O3 as promoters and Al2O3, CeO2-ZrO2, SiO2 and TiO2 as support materials. The catalysts were tested in a bench-scale reactor and characterized by using N2-BET, XRD, H2 chemisorption, H2-TPR, O2-TPO, XPS and TEM analyses. The second part addresses the development and testing of full-scale reformers at various realistic operating conditions using promising Rh catalysts.

The thesis shows that a variety of Rh on alumina catalysts was successfully tested for ATR of diesel (Papers I-IV). Also, zone-coating, meaning adding two washcoats on specific parts of the monolith, was found to have beneficial effects on the ATR catalyst performance (Paper II). In addition, RhPt supported on CeO2-ZrO2 was found to be one of the most active and promising catalyst candidates for ATR of diesel. The superior performance may be attributed to higher reducibility of RhiOx species and greater dispersion of Rh and Pt on the support (Paper IV). Finally, two full-scale diesel reformers were successfully developed and proven capable of providing high fuel conversion and hydrogen production from commercial diesel over selected Rh catalysts (Papers II-III, V-VI).

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. x, 81 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2011:28
Keyword
Autothermal reforming, auxiliary power unit, BET, chemisorption, diesel, fuel cell, hydrogen, monolith, reforming catalyst, reformer design, Rh, RhPt alloy, TEM, TPO, TPR, XRD, XPS, zone coating
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-32647 (URN)978-91-7415-945-5 (ISBN)
Public defence
2011-04-29, KTH - Sal F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20110418Available from: 2011-04-18 Created: 2011-04-18 Last updated: 2011-04-18Bibliographically approved

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