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Characterization and optimization of an autothermal diesel and jet fuel reformer for 5 kW(e) mobile fuel cell applications
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
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2010 (English)In: Chemical Engineering Journal, ISSN 1385-8947, Vol. 156, no 2, 366-379 p.Article in journal (Refereed) Published
Abstract [en]

The present paper describes the characterization of an autothermal reformer designed to generate hydrogen by autothermal reforming (ATR) from commercial diesel fuel (similar to 10 ppm S) and jet fuel (similar to 200 ppm S) for a 5 kW(e) polymer electrolyte fuel cell (PEFC). Commercial noble metal-based catalysts supported on 900 cpsi cordierite monoliths substrates were used for ATR with reproducible results. Parameters investigated in this study were the variation of the fuel inlet temperature, fuel flow and the H2O/C and O-2/C ratios. Temperature profiles were studied both in the axial and radial directions of the reformer. Product gas composition was analyzed using gas chromatography. It was concluded from the experiments that an elevated fuel inlet temperature (>= 60 degrees C) and a higher degree of fuel dispersion, generated via a single-fluid pressurized-swirl nozzle at high fuel flow, significantly improved the performance of the reformer. Complete fuel conversion, a reforming efficiency of 81% and an H-2 selectivity of 96% were established for ATR of diesel at P=5kW(e), H2O/C = 2.5, O-2/C = 0.49 and a fuel inlet temperature of 60 degrees C. No hot-spot formation and negligible coke formation were observed in the reactor at these operating conditions. The reforming of jet fuel resulted in a reforming efficiency of only 42%. A plausible cause is the coke deposition, originating from the aromatics present in the fuel, and the adsorption of S-compounds on the active sites of the reforming catalyst. Our results indicate possibilities for the developed catalytic reformer to be used in mobile fuel cell applications for energy-efficient hydrogen production from diesel fuel.

Place, publisher, year, edition, pages
2010. Vol. 156, no 2, 366-379 p.
Keyword [en]
Autothermal reformer, Diesel, Fuel flow, Fuel preheating, Jet fuel, Monolithic catalyst, catalytic partial oxidation, auxiliary power units, liquid, hydrocarbons, hydrogen, sulfur, performance, scale, technologies
National Category
Chemical Engineering Other Environmental Engineering
URN: urn:nbn:se:kth:diva-19239DOI: 10.1016/j.cej.2009.10.039ISI: 000274771400018ScopusID: 2-s2.0-73249135810OAI: diva2:337286
QC 20110210Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2011-04-18Bibliographically 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.
Trita-CHE-Report, ISSN 1654-1081 ; 2011:28
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
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)
QC 20110418Available from: 2011-04-18 Created: 2011-04-18 Last updated: 2011-04-18Bibliographically approved

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