Aqueous-phase reforming: multiphase reaction engineering at the microscale

Renée Maria Ripken

    Research output: ThesisPhD Thesis - Research UT, graduation UT

    101 Downloads (Pure)

    Abstract

    Hydrogen has been identified as an interesting alternative for fossil fuels. Conventionally,
    hydrogen is produced from natural gas or oil, using high temperature and pressure methods such
    as steam reforming. In 2002, Aqueous-Phase Reforming (APR) was introduced to reform
    oxygenated carbohydrates into hydrogen at more environmental friendly reaction conditions.
    In this dissertation, various thermodynamic aspects related to Aqueous-Phase Reforming, as well
    as various reactor designs have been discussed. Here, process technological aspects have been
    investigated at the microscale using both theoretical and experimental methods, mainly focusing
    on the thermodynamics and transport phenomena involved in APR.
    The reaction thermodynamics have been evaluated in terms of the enthalpy and Gibbs free energy
    of reaction. In addition, the phase state of the reaction mixture at APR reaction conditions has been
    studied. To experimentally validate the phase transitions, a high-pressure high-temperature
    microfluidic platform has been developed, in which also the boiling mechanisms and the gas/liquid
    flow patterns were observed.
    Depending on the characteristics, gaseous APR products that form as bubbles on the catalytic
    surface may affect transport phenomena. In addition to 2D and 3D-numerical models to investigate
    these properties, a transparent microreactor containing hydrophobic micropits has been developed
    to aid bubble nucleation and controlling transport phenomena in catalytic multiphase microreactors
    in the future.
    Introducing a heterogeneous catalyst is essential for APR microreactors. Both spark discharge and
    washcoating techniques have been studied for the controlled deposition of catalytic materials in
    microreactors. After reaction, the resulting gas/liquid product streams have to be separated, for
    which a modular gas/liquid microseparator has been developed. The required low dead volume
    and the in- and outlet design have received special attention.
    Although APR is already a great improvement over conventional hydrogen production methods,
    it is still dependent on a substantial amount of externally supplied heat. In contrast, photocatalytic
    reforming (PhCR) of biomass, where biomass is reformed into hydrogen and CO2 using only
    sunlight, is an attractive alternative. In parallel, first steps towards studying these aspects with a
    microfluidic device were successfully taken.
    Finally, the possible commercialization of APR for hydrogen production has been discussed in the
    outlook of the thesis.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Awarding Institution
    • University of Twente
    Supervisors/Advisors
    • Gardeniers, J.G.E., Supervisor
    • le Gac, Severine , Co-Supervisor
    Award date28 Jun 2019
    Place of PublicationEnschede
    Publisher
    Print ISBNs978-90-365-4784-0
    DOIs
    Publication statusPublished - 28 Jun 2019

    Fingerprint

    Reforming reactions
    Hydrogen
    Gases
    Thermodynamics
    Hydrogen production
    Biomass
    Steam reforming
    Liquids
    Electric sparks
    Fossil fuels
    Boiling liquids
    Numerical models
    Enthalpy
    Natural gas
    Oils
    Nucleation
    Phase transitions
    Carbohydrates
    Catalysts

    Cite this

    Ripken, Renée Maria. / Aqueous-phase reforming : multiphase reaction engineering at the microscale. Enschede : University of Twente, 2019. 202 p.
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    title = "Aqueous-phase reforming: multiphase reaction engineering at the microscale",
    abstract = "Hydrogen has been identified as an interesting alternative for fossil fuels. Conventionally,hydrogen is produced from natural gas or oil, using high temperature and pressure methods suchas steam reforming. In 2002, Aqueous-Phase Reforming (APR) was introduced to reformoxygenated carbohydrates into hydrogen at more environmental friendly reaction conditions.In this dissertation, various thermodynamic aspects related to Aqueous-Phase Reforming, as wellas various reactor designs have been discussed. Here, process technological aspects have beeninvestigated at the microscale using both theoretical and experimental methods, mainly focusingon the thermodynamics and transport phenomena involved in APR.The reaction thermodynamics have been evaluated in terms of the enthalpy and Gibbs free energyof reaction. In addition, the phase state of the reaction mixture at APR reaction conditions has beenstudied. To experimentally validate the phase transitions, a high-pressure high-temperaturemicrofluidic platform has been developed, in which also the boiling mechanisms and the gas/liquidflow patterns were observed.Depending on the characteristics, gaseous APR products that form as bubbles on the catalyticsurface may affect transport phenomena. In addition to 2D and 3D-numerical models to investigatethese properties, a transparent microreactor containing hydrophobic micropits has been developedto aid bubble nucleation and controlling transport phenomena in catalytic multiphase microreactorsin the future.Introducing a heterogeneous catalyst is essential for APR microreactors. Both spark discharge andwashcoating techniques have been studied for the controlled deposition of catalytic materials inmicroreactors. After reaction, the resulting gas/liquid product streams have to be separated, forwhich a modular gas/liquid microseparator has been developed. The required low dead volumeand the in- and outlet design have received special attention.Although APR is already a great improvement over conventional hydrogen production methods,it is still dependent on a substantial amount of externally supplied heat. In contrast, photocatalyticreforming (PhCR) of biomass, where biomass is reformed into hydrogen and CO2 using onlysunlight, is an attractive alternative. In parallel, first steps towards studying these aspects with amicrofluidic device were successfully taken.Finally, the possible commercialization of APR for hydrogen production has been discussed in theoutlook of the thesis.",
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    Aqueous-phase reforming : multiphase reaction engineering at the microscale. / Ripken, Renée Maria.

    Enschede : University of Twente, 2019. 202 p.

    Research output: ThesisPhD Thesis - Research UT, graduation UT

    TY - THES

    T1 - Aqueous-phase reforming

    T2 - multiphase reaction engineering at the microscale

    AU - Ripken, Renée Maria

    PY - 2019/6/28

    Y1 - 2019/6/28

    N2 - Hydrogen has been identified as an interesting alternative for fossil fuels. Conventionally,hydrogen is produced from natural gas or oil, using high temperature and pressure methods suchas steam reforming. In 2002, Aqueous-Phase Reforming (APR) was introduced to reformoxygenated carbohydrates into hydrogen at more environmental friendly reaction conditions.In this dissertation, various thermodynamic aspects related to Aqueous-Phase Reforming, as wellas various reactor designs have been discussed. Here, process technological aspects have beeninvestigated at the microscale using both theoretical and experimental methods, mainly focusingon the thermodynamics and transport phenomena involved in APR.The reaction thermodynamics have been evaluated in terms of the enthalpy and Gibbs free energyof reaction. In addition, the phase state of the reaction mixture at APR reaction conditions has beenstudied. To experimentally validate the phase transitions, a high-pressure high-temperaturemicrofluidic platform has been developed, in which also the boiling mechanisms and the gas/liquidflow patterns were observed.Depending on the characteristics, gaseous APR products that form as bubbles on the catalyticsurface may affect transport phenomena. In addition to 2D and 3D-numerical models to investigatethese properties, a transparent microreactor containing hydrophobic micropits has been developedto aid bubble nucleation and controlling transport phenomena in catalytic multiphase microreactorsin the future.Introducing a heterogeneous catalyst is essential for APR microreactors. Both spark discharge andwashcoating techniques have been studied for the controlled deposition of catalytic materials inmicroreactors. After reaction, the resulting gas/liquid product streams have to be separated, forwhich a modular gas/liquid microseparator has been developed. The required low dead volumeand the in- and outlet design have received special attention.Although APR is already a great improvement over conventional hydrogen production methods,it is still dependent on a substantial amount of externally supplied heat. In contrast, photocatalyticreforming (PhCR) of biomass, where biomass is reformed into hydrogen and CO2 using onlysunlight, is an attractive alternative. In parallel, first steps towards studying these aspects with amicrofluidic device were successfully taken.Finally, the possible commercialization of APR for hydrogen production has been discussed in theoutlook of the thesis.

    AB - Hydrogen has been identified as an interesting alternative for fossil fuels. Conventionally,hydrogen is produced from natural gas or oil, using high temperature and pressure methods suchas steam reforming. In 2002, Aqueous-Phase Reforming (APR) was introduced to reformoxygenated carbohydrates into hydrogen at more environmental friendly reaction conditions.In this dissertation, various thermodynamic aspects related to Aqueous-Phase Reforming, as wellas various reactor designs have been discussed. Here, process technological aspects have beeninvestigated at the microscale using both theoretical and experimental methods, mainly focusingon the thermodynamics and transport phenomena involved in APR.The reaction thermodynamics have been evaluated in terms of the enthalpy and Gibbs free energyof reaction. In addition, the phase state of the reaction mixture at APR reaction conditions has beenstudied. To experimentally validate the phase transitions, a high-pressure high-temperaturemicrofluidic platform has been developed, in which also the boiling mechanisms and the gas/liquidflow patterns were observed.Depending on the characteristics, gaseous APR products that form as bubbles on the catalyticsurface may affect transport phenomena. In addition to 2D and 3D-numerical models to investigatethese properties, a transparent microreactor containing hydrophobic micropits has been developedto aid bubble nucleation and controlling transport phenomena in catalytic multiphase microreactorsin the future.Introducing a heterogeneous catalyst is essential for APR microreactors. Both spark discharge andwashcoating techniques have been studied for the controlled deposition of catalytic materials inmicroreactors. After reaction, the resulting gas/liquid product streams have to be separated, forwhich a modular gas/liquid microseparator has been developed. The required low dead volumeand the in- and outlet design have received special attention.Although APR is already a great improvement over conventional hydrogen production methods,it is still dependent on a substantial amount of externally supplied heat. In contrast, photocatalyticreforming (PhCR) of biomass, where biomass is reformed into hydrogen and CO2 using onlysunlight, is an attractive alternative. In parallel, first steps towards studying these aspects with amicrofluidic device were successfully taken.Finally, the possible commercialization of APR for hydrogen production has been discussed in theoutlook of the thesis.

    U2 - 10.3990/1.9789036547840

    DO - 10.3990/1.9789036547840

    M3 - PhD Thesis - Research UT, graduation UT

    SN - 978-90-365-4784-0

    PB - University of Twente

    CY - Enschede

    ER -