Bio-oil production via catalytic fast pyrolysis of woody biomass

Dissertation

Ville Paasikallio

    Research output: ThesisDissertationCollection of Articles

    Abstract

    Fast pyrolysis of biomass is a thermochemical conversion process where solid biomass such as wood is thermally converted under a non-oxidative atmosphere at a temperature of approximately 500°C. The main product from this process is bio-oil, a highly oxygenated liquid with very challenging fuel properties. The quality of the bio-oil can be improved using a variety of catalytic processes. One such technology is catalytic fast pyrolysis (CFP), which integrates a catalytic vapor-phase upgrading step directly into a fast pyrolysis process itself. The overall purpose of this is to improve the quality of the bio-oil that is produced in the fast pyrolysis process. This, in turn, can facilitate easier utilization of the bio-oil in demanding applications such as upgrading to transportation fuels. CFP is most often carried out using acidic zeolite catalysts, which are capable of removing oxygen from the pyrolysis vapors in the form of carbon oxides and water. Because both carbon and hydrogen are lost together with the oxygen, the quality of bio-oil improves at the expense of the yield. Acidic catalysts and highly oxygenated pyrolysis vapors are a combination which results in rapid catalyst deactivation due to coke formation. In order to maintain an adequate level of catalyst activity, the catalyst must be regenerated on a frequent basis. From the perspective of continuous operation, this sets certain requirements on the reactor technology for CFP. The results of this thesis show that bubbling fluidized bed reactors, which are commonly used for research purposes and do not normally include the possibility of continuous catalyst addition and removal, have clear operational limitations for CFP. Such reactors can, nevertheless, be used for catalyst testing and parametric studies as long as the effect of short-term catalyst deactivation is taken into account. Circulating fluidized bed reactors with continuous catalyst regeneration provide a much more convenient technological platform for CFP. The effect of coke-induced reversible deactivation is effectively negated, and the focus can be shifted to process performance and catalyst longterm stability. The latter factor is considered to be one of the key questions for CFP. It was shown in this thesis that the combination of biomass-derived inorganic contaminants and severe reaction/regeneration conditions cause irreversible changes in the catalyst structure and properties, which in turn reflects in the quality of the bio-oil. The results of this thesis also highlight the diverse overall character of the CFP products. The partially upgraded bio-oil product is accompanied by a separate aqueous liquid with varying amounts of dissolved organics. Thus, efficient utilization of the CFP products would very likely entail more than one valorization approach.
    Original languageEnglish
    QualificationDoctor Degree
    Awarding Institution
    • Aalto University
    Supervisors/Advisors
    • Seppälä, Jukka, Supervisor, External person
    • Lehto, Jani, Advisor
    • Lehtonen, Juha, Advisor
    Award date11 Nov 2016
    Place of PublicationEspoo
    Publisher
    Print ISBNs978-952-60-7104-6, 978-951-38-8466-6
    Electronic ISBNs978-952-60-7103-9, 978-951-38-8465-9
    Publication statusPublished - 2016
    MoE publication typeG5 Doctoral dissertation (article)

    Fingerprint

    Biomass
    Pyrolysis
    Catalysts
    Catalyst deactivation
    Vapors
    Coke
    Oils
    Fluidized beds
    Catalyst regeneration
    Bioconversion
    Carbon
    Oxygen
    Liquids
    Catalyst activity
    Wood
    Impurities
    Hydrogen
    Oxides
    Testing

    Keywords

    • biomass
    • biofuels
    • bio-oil
    • pyrolysis
    • catalysis

    Cite this

    Paasikallio, Ville. / Bio-oil production via catalytic fast pyrolysis of woody biomass : Dissertation. Espoo : Aalto University, 2016. 166 p.
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    abstract = "Fast pyrolysis of biomass is a thermochemical conversion process where solid biomass such as wood is thermally converted under a non-oxidative atmosphere at a temperature of approximately 500°C. The main product from this process is bio-oil, a highly oxygenated liquid with very challenging fuel properties. The quality of the bio-oil can be improved using a variety of catalytic processes. One such technology is catalytic fast pyrolysis (CFP), which integrates a catalytic vapor-phase upgrading step directly into a fast pyrolysis process itself. The overall purpose of this is to improve the quality of the bio-oil that is produced in the fast pyrolysis process. This, in turn, can facilitate easier utilization of the bio-oil in demanding applications such as upgrading to transportation fuels. CFP is most often carried out using acidic zeolite catalysts, which are capable of removing oxygen from the pyrolysis vapors in the form of carbon oxides and water. Because both carbon and hydrogen are lost together with the oxygen, the quality of bio-oil improves at the expense of the yield. Acidic catalysts and highly oxygenated pyrolysis vapors are a combination which results in rapid catalyst deactivation due to coke formation. In order to maintain an adequate level of catalyst activity, the catalyst must be regenerated on a frequent basis. From the perspective of continuous operation, this sets certain requirements on the reactor technology for CFP. The results of this thesis show that bubbling fluidized bed reactors, which are commonly used for research purposes and do not normally include the possibility of continuous catalyst addition and removal, have clear operational limitations for CFP. Such reactors can, nevertheless, be used for catalyst testing and parametric studies as long as the effect of short-term catalyst deactivation is taken into account. Circulating fluidized bed reactors with continuous catalyst regeneration provide a much more convenient technological platform for CFP. The effect of coke-induced reversible deactivation is effectively negated, and the focus can be shifted to process performance and catalyst longterm stability. The latter factor is considered to be one of the key questions for CFP. It was shown in this thesis that the combination of biomass-derived inorganic contaminants and severe reaction/regeneration conditions cause irreversible changes in the catalyst structure and properties, which in turn reflects in the quality of the bio-oil. The results of this thesis also highlight the diverse overall character of the CFP products. The partially upgraded bio-oil product is accompanied by a separate aqueous liquid with varying amounts of dissolved organics. Thus, efficient utilization of the CFP products would very likely entail more than one valorization approach.",
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    Paasikallio, V 2016, 'Bio-oil production via catalytic fast pyrolysis of woody biomass: Dissertation', Doctor Degree, Aalto University, Espoo.

    Bio-oil production via catalytic fast pyrolysis of woody biomass : Dissertation. / Paasikallio, Ville.

    Espoo : Aalto University, 2016. 166 p.

    Research output: ThesisDissertationCollection of Articles

    TY - THES

    T1 - Bio-oil production via catalytic fast pyrolysis of woody biomass

    T2 - Dissertation

    AU - Paasikallio, Ville

    N1 - BA3114

    PY - 2016

    Y1 - 2016

    N2 - Fast pyrolysis of biomass is a thermochemical conversion process where solid biomass such as wood is thermally converted under a non-oxidative atmosphere at a temperature of approximately 500°C. The main product from this process is bio-oil, a highly oxygenated liquid with very challenging fuel properties. The quality of the bio-oil can be improved using a variety of catalytic processes. One such technology is catalytic fast pyrolysis (CFP), which integrates a catalytic vapor-phase upgrading step directly into a fast pyrolysis process itself. The overall purpose of this is to improve the quality of the bio-oil that is produced in the fast pyrolysis process. This, in turn, can facilitate easier utilization of the bio-oil in demanding applications such as upgrading to transportation fuels. CFP is most often carried out using acidic zeolite catalysts, which are capable of removing oxygen from the pyrolysis vapors in the form of carbon oxides and water. Because both carbon and hydrogen are lost together with the oxygen, the quality of bio-oil improves at the expense of the yield. Acidic catalysts and highly oxygenated pyrolysis vapors are a combination which results in rapid catalyst deactivation due to coke formation. In order to maintain an adequate level of catalyst activity, the catalyst must be regenerated on a frequent basis. From the perspective of continuous operation, this sets certain requirements on the reactor technology for CFP. The results of this thesis show that bubbling fluidized bed reactors, which are commonly used for research purposes and do not normally include the possibility of continuous catalyst addition and removal, have clear operational limitations for CFP. Such reactors can, nevertheless, be used for catalyst testing and parametric studies as long as the effect of short-term catalyst deactivation is taken into account. Circulating fluidized bed reactors with continuous catalyst regeneration provide a much more convenient technological platform for CFP. The effect of coke-induced reversible deactivation is effectively negated, and the focus can be shifted to process performance and catalyst longterm stability. The latter factor is considered to be one of the key questions for CFP. It was shown in this thesis that the combination of biomass-derived inorganic contaminants and severe reaction/regeneration conditions cause irreversible changes in the catalyst structure and properties, which in turn reflects in the quality of the bio-oil. The results of this thesis also highlight the diverse overall character of the CFP products. The partially upgraded bio-oil product is accompanied by a separate aqueous liquid with varying amounts of dissolved organics. Thus, efficient utilization of the CFP products would very likely entail more than one valorization approach.

    AB - Fast pyrolysis of biomass is a thermochemical conversion process where solid biomass such as wood is thermally converted under a non-oxidative atmosphere at a temperature of approximately 500°C. The main product from this process is bio-oil, a highly oxygenated liquid with very challenging fuel properties. The quality of the bio-oil can be improved using a variety of catalytic processes. One such technology is catalytic fast pyrolysis (CFP), which integrates a catalytic vapor-phase upgrading step directly into a fast pyrolysis process itself. The overall purpose of this is to improve the quality of the bio-oil that is produced in the fast pyrolysis process. This, in turn, can facilitate easier utilization of the bio-oil in demanding applications such as upgrading to transportation fuels. CFP is most often carried out using acidic zeolite catalysts, which are capable of removing oxygen from the pyrolysis vapors in the form of carbon oxides and water. Because both carbon and hydrogen are lost together with the oxygen, the quality of bio-oil improves at the expense of the yield. Acidic catalysts and highly oxygenated pyrolysis vapors are a combination which results in rapid catalyst deactivation due to coke formation. In order to maintain an adequate level of catalyst activity, the catalyst must be regenerated on a frequent basis. From the perspective of continuous operation, this sets certain requirements on the reactor technology for CFP. The results of this thesis show that bubbling fluidized bed reactors, which are commonly used for research purposes and do not normally include the possibility of continuous catalyst addition and removal, have clear operational limitations for CFP. Such reactors can, nevertheless, be used for catalyst testing and parametric studies as long as the effect of short-term catalyst deactivation is taken into account. Circulating fluidized bed reactors with continuous catalyst regeneration provide a much more convenient technological platform for CFP. The effect of coke-induced reversible deactivation is effectively negated, and the focus can be shifted to process performance and catalyst longterm stability. The latter factor is considered to be one of the key questions for CFP. It was shown in this thesis that the combination of biomass-derived inorganic contaminants and severe reaction/regeneration conditions cause irreversible changes in the catalyst structure and properties, which in turn reflects in the quality of the bio-oil. The results of this thesis also highlight the diverse overall character of the CFP products. The partially upgraded bio-oil product is accompanied by a separate aqueous liquid with varying amounts of dissolved organics. Thus, efficient utilization of the CFP products would very likely entail more than one valorization approach.

    KW - biomass

    KW - biofuels

    KW - bio-oil

    KW - pyrolysis

    KW - catalysis

    M3 - Dissertation

    SN - 978-952-60-7104-6

    SN - 978-951-38-8466-6

    T3 - VTT Science

    PB - Aalto University

    CY - Espoo

    ER -

    Paasikallio V. Bio-oil production via catalytic fast pyrolysis of woody biomass: Dissertation. Espoo: Aalto University, 2016. 166 p.