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Fuel Reforming for Hydrogen Production in Heavy-Duty Vehicle Applications
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.ORCID iD: 0000-0001-9601-1959
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The depletion of fossil fuels together with growing environmental concerns have created incitement for developing a more energy-efficient and environmentally-friendly vehicle fleet. The development towards cleaner heavy-duty vehicles started already in the 80’s with the introduction of emission legislations. Initially, engine optimization was enough for reaching the legislated levels of emissions. However, at present engine optimization is not enough but exhaust aftertreatment has become an essential part of heavy-duty vehicles, in order to meet the emission standards. Today, the total emissions are targeted which means that there is an interest in decreasing the idling emissions as well as the emissions during operation. To reduce the overall emissions several states in the USA have introduced idling legislations. Due to the limitations in idling time alternative solutions for power generation during rests are requested. A possible alternative is a fuel cell auxiliary power unit, combining a fuel cell with a fuel reformer (FC-APU). 

The focus of this thesis is the development of the fuel reformer for an FC-APU, in which the hydrogen to the fuel cell is generated from diesel in a high-temperature catalytic process. The produced hydrogen can also be used in other heavy-duty vehicle applications i.e. selective catalytic reduction of NOx (HC-SCR), where addition of hydrogen is essential for reaching high conversion at low temperatures. The effect of using hydrogen from a fuel reformer in HC-SCR is included in this work. The catalytic material development is focused on developing promoted materials with lower rhodium content but with catalytic activity comparable to that of materials with higher rhodium content. This includes evaluation and extensive characterization of both fresh and aged promoted materials. The work also includes reactor design where a micro reactor with multiple air inlets is evaluated.

This work has contributed to increased knowledge of catalytic materials suitable for reforming of diesel. By changing the support material from the traditionally used alumina to ceria-zirconia, increased H2 yield was achieved. In addition, the ceria-zirconia supported material was less prone to coke. By promoting the material with cobalt or lanthanum it was possible to decrease the rhodium content by 2/3 with enhanced catalytic performance. It was also discovered that promotion with lanthanum decreased the tendency for coking even further. Additionally, the lanthanum-promoted material had higher thermal stability as well as a stable highly dispersed rhodium phase.

Furthermore, the work has contributed to an increased knowledge concerning the fuel reformer’s effect on HC-SCR. The work displays clear evidence of benefits with using hydrogen-rich gas from a fuel reformer instead of pure hydrogen. The benefits are derived from the content of low molecular weight hydrocarbons present in the hydrogen-rich gas, which are strong reducing agents increasing the NOx reduction. This finding proves that fuel reforming in combination with HC-SCR is a viable option for NOx abatement.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , xi, 66 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:6
Keyword [en]
aging · autothermal fuel reforming · CeO2-ZrO2 · characterization · diesel · H2-assisted HC-SCR · micro reactor · monolith
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-159423ISBN: 978-91-7595-412-7 (print)OAI: oai:DiVA.org:kth-159423DiVA: diva2:784896
Public defence
2015-02-27, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Mistra - The Swedish Foundation for Strategic Environmental Research
Note

QC 20150202

Available from: 2015-02-02 Created: 2015-01-29 Last updated: 2015-02-02Bibliographically approved
List of papers
1. Comparison between ceria-zirconia and alumina as supports for oxidative steam reforming of biodiesel
Open this publication in new window or tab >>Comparison between ceria-zirconia and alumina as supports for oxidative steam reforming of biodiesel
2015 (English)In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 58, no 14-17, 933-938 p.Article in journal (Other academic) Published
Abstract [en]

The objective of the study is to illustrate the advantages with using ceria–zirconia instead of promoted alumina as support for rhodium-based catalysts in oxidative steam reforming of biodiesel. The evaluation is based on long-term oxidative steam reforming experiments where the stability and durability of the catalysts are evaluated. The durability and fuel conversion of the two catalysts were comparable. However, the H2 yield of the ceria–zirconia supported catalyst was 10 % higher than for the catalyst supported on promoted alumina after 65 h on stream. Included are also measurements of the acidity of the catalysts, where it was concluded that the promoted alumina catalyst was significantly more acidic. The acidity of the materials could then be related to the amount of coke deposited, where the amount of coke on the alumina catalyst was almost five times higher after 50 h of operation compared to the ceria–zirconia catalyst.

Place, publisher, year, edition, pages
New York: Springer, 2015
Keyword
acidity · alumina · biodiesel · ceria-zircona coking · oxidative steam reforming
National Category
Chemical Process Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-159469 (URN)10.1007/s11244-015-0461-2 (DOI)000362581900013 ()
Note

QC 20151103

Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2017-12-05Bibliographically approved
2. Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel
Open this publication in new window or tab >>Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel
Show others...
2014 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 154, 386-394 p.Article in journal (Refereed) Published
Abstract [en]

The objective of this paper was to study the influence three promoters (Co, La, Mn) had on the catalytic activity of Rh-based catalysts for autothermal reforming of diesel. The catalysts were supported on CeO2ZrO2 and the loading was 1 wt.% Rh and 6 wt.% promoter. The catalytic activity was evaluated in a monolith bench scale reactor with Swedish Environmental diesel, MK1. The process parameters employed at the ATR experiments were; O-2/C similar to 0.45, H2O/C similar to 2.5 and GHSV similar to 50,000h(-1), meanwhile the reactor temperature was ramped from 700 degrees C to 950 degrees C. The catalysts were compared based on their fuel conversion, H-2 yield and the selectivity of different short-chain hydrocarbons. The results showed that all three catalysts had both high fuel conversion and H-2 yield in the optimal ATR operation temperatures. The H-2 yield and fuel conversion were increasing in the order Rh/Mn, Rh/La, Rh/Co. To get further insight in the difference between the materials the fresh and aged catalytic materials were characterized. The characterization methods used were H-2-temperature programmed reduction (H-2-TPR), powder X-ray diffraction (XRD), and BET surface measurements. The BET surface measurements showed that promotion with La gave improved thermal stability of the material. The XRD showed a high dispersion of all metals except Co, which was present as crystals in the size range of the particles of the support.

Keyword
Autothermal reforming, Rhodium, Bimetallic, Diesel, Monolith
National Category
Chemical Process Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-145711 (URN)10.1016/j.apcatb.2014.02.043 (DOI)000335098800045 ()2-s2.0-84896119618 (Scopus ID)
Funder
Mistra - The Swedish Foundation for Strategic Environmental Research
Note

QC 20150623

Available from: 2014-05-27 Created: 2014-05-27 Last updated: 2017-12-05Bibliographically approved
3. Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel: Aging and characterization
Open this publication in new window or tab >>Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel: Aging and characterization
Show others...
2015 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 172, 145-153 p.Article in journal (Refereed) Published
Abstract [en]

In this study three bimetallic catalysts are evaluated for autothermal reforming (ATR) of fuels (1 wt.% Rh and 6 wt.% X (X = Co, La or Mn) supported on high-surface area CeO2-ZrO2). The catalysts are aged for approximately 35 h and carefully characterized both as fresh and aged materials. The objective is to illuminate the changes in material properties after time on stream as well as the differences among the materials. The changes in material properties are evaluated by H2-TPR, BET surface area analysis, TEM, SEM and STEM. The material’s tendency to coke is investigated by TPO analysis.

The three materials exhibit promising initial activity. However, the Co-promoted sample decreases sharply in activity after 25 h of operation. Meanwhile, the other two materials display a more stable activity throughout the evaluated time. The deactivation of the Co-promoted material could be linked to the high amount of coke deposited during operation. Based on the results from the activity evaluation and characterization, the material promoted with lanthanum displays the most promising results. The addition of lanthanum resulted in a catalyst that was both stable and had high activity, even though a low rhodium loading is used. The material also shows superior thermal resistance compared to the other two materials. In addition, the tendency to coke is significantly lower compered to the other materials, which is especially beneficial when dealing with ATR of complex fuels. 

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
autothermal reforming, characterization, diesel, deactivation, morphology
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-159470 (URN)10.1016/j.apcatb.2015.02.018 (DOI)000352170400018 ()2-s2.0-84924213317 (Scopus ID)
Funder
Mistra - The Swedish Foundation for Strategic Environmental ResearchKnut and Alice Wallenberg Foundation
Note

QC 20150519

Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2017-12-05Bibliographically approved
4. Comparison between a micro reactor with multiple air inlets and a monolith reactor for oxidative steam reforming of diesel
Open this publication in new window or tab >>Comparison between a micro reactor with multiple air inlets and a monolith reactor for oxidative steam reforming of diesel
2014 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 31, 18037-18045 p.Article in journal (Refereed) Published
Abstract [en]

Abstract In order to lower the emission from idling heavy-duty trucks auxiliary power units can be implemented. Due to limited space available on-board the truck the units needs to be both efficient and compact. One alternative for these units is a fuel cell supplied with hydrogen from a fuel reformer. Today, mostly monolithic reactors are used in the field of oxidative steam reforming of fuels, which has some challenges that need to be addressed before a possible breakthrough occurs on the market. One is the temperature gradient developed over the length of the monolith as a consequence of the sequential reactions. This could be improved by using a metallic micro reactor with better heat integration between the reaction zones and further improving the integration with multiple air inlets along the catalytic bed. The aim with this study was to compare a conventional monolith reactor for oxidative steam reforming of fuel with a novel micro reactor design where air was dosed at four different positions along the reactor channels. The experiments were not necessarily conducted autothermal, i.e. a heating jacket was applied for operation.

Keyword
Oxidative steam reforming, Diesel, Micro reactor, Monolith reactor, Multiple air inlets
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-149331 (URN)10.1016/j.ijhydene.2014.06.096 (DOI)000343781100052 ()2-s2.0-84914168559 (Scopus ID)
Note

QC 20141128

Available from: 2014-08-20 Created: 2014-08-20 Last updated: 2017-12-05Bibliographically approved
5. Combining HC-SCR over Ag/Al2O3 and hydrogen generation over Rh/CeO2-ZrO2 using biofuels: An integrated system approach for real applications
Open this publication in new window or tab >>Combining HC-SCR over Ag/Al2O3 and hydrogen generation over Rh/CeO2-ZrO2 using biofuels: An integrated system approach for real applications
Show others...
2015 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 162, 583-592 p.Article in journal (Refereed) Published
Abstract [en]

Abstract We report on a high NOx reduction activity over Ag/Al2O3 catalysts, using hydrogen produced in a fuel reformer. The focus of the study is to evaluate the performance of a hydrocarbon selective catalytic reduction (HC-SCR) catalyst in real conditions. Initially, the catalytic materials for the fuel reformer (Rh/CeO2-ZrO2) and the HC-SCR (Ag/Al2O3) were evaluated in separate bench-scale reactor setups. These two setups were subsequently joined into an integrated bench-scale reactor setup with the aim to evaluate the influence of the reformate on the HC-SCR activity in a controlled environment. In the final phase of the study a 4 wt.% Ag/Al2O3 catalyst doped with 100 ppm(w) Pt was scaled up and tested in a pilot-scale reactor setup. The pilot-scale reactor setup enabled evaluation of the HC-SCR activity in real exhaust gases generated by a single cylinder engine (genset) together with a hydrogen-rich gas supplied from a fuel reformer. Commercial biodiesel (NExBTL) was used as reducing agent for the HC-SCR as well as fuel in the fuel reformer for both the bench-scale and pilot-scale experiments. This study gives an excellent link between evaluations of the catalytic materials, controlled bench-scale experiments and applied engine experiments, proving a viable concept for lean NOx reduction together with onboard hydrogen production. A NOx conversion of above 70% was reached at temperatures below 250 °C, in bench-scale experiments when hydrogen produced in the fuel reformer is added.

Keyword
HC-SCR fuel reformer integrated system, Ag/Al2O3, Rh/CeO2-ZrO2, Biofuels, Diesel engine
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-149332 (URN)10.1016/j.apcatb.2014.07.036 (DOI)000343686900067 ()2-s2.0-84905367908 (Scopus ID)
Funder
Mistra - The Swedish Foundation for Strategic Environmental ResearchSwedish Energy AgencyKnut and Alice Wallenberg Foundation, Dnr KAW 2005.0055
Note

QC 20140902

Available from: 2014-08-20 Created: 2014-08-20 Last updated: 2017-12-05Bibliographically approved

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  • harvard1
  • ieee
  • modern-language-association-8th-edition
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