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Cited by 10Catalysis and Hydrodesulfurization StudiesCatalysts for Methane ReformingBiodiesel Production and Applications

Catalytic Hydroprocessing of Single-Cell Oils to Hydrocarbon Fuels: Converting microbial lipids to fuels is a promising approach to replace fossil fuels

Open access
Kruger, Jacob S., Knoshaug, Eric P., Dong, Tao, Hull, Tobias C., Pienkos, Philip T.·2021·Johnson Matthey Technology Review
DOI 10.1595/205651321x16024905831259
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Abstract

Microbial lipids hold great promise as biofuel precursors, and research efforts to convert such lipids to renewable diesel fuels have been increasing in recent years. In contrast to the numerous literature reviews on growing, characterising and extracting lipids from oleaginous microbes, and on converting vegetable oils to hydrocarbon fuels, this review aims to provide insight into aspects that are specific to hydroprocessing microbial lipids. While standard hydrotreating catalysts generally perform well with terrestrial oils, differences in lipid speciation and the presence of co-extracted compounds, such as chlorophyll and sterols, introduce additional complexities into the process for microbial lipids. Lipid cleanup steps can be introduced to produce suitable feedstocks for catalytic upgrading.

AI snapshot

Written from the paper’s full text.

TL;DR

This review examines catalytic hydroprocessing of single-cell oils (SCOs) to hydrocarbon fuels, focusing on how microbial lipids differ from terrestrial oils in recovery, composition, cleanup, and catalyst performance. It concludes that SCOs are promising but require tailored cleanup and integrated process design, while catalyst stability data remain limited.

Key findings

  • SCOs share major fatty acids with plant oils but contain broader lipid classes; glycolipids and phospholipids can account for 17–90% of total lipids in autotrophically grown algae versus ~2% in soybean oil, and co-extracted chlorophyll, sterols, terpenes, carotenoids, and free fatty acids can poison catalysts or worsen cold flow.
  • Cleanup matters: phosphoric-acid-catalysed dealkylation removed 99.7% of chlorophyll from algae oil; in a direct comparison, acid bleaching removed 92% of oil nitrogen with no detectable chlorophyll UV-vis signal, while silica adsorption removed 85% nitrogen and still showed detectable chlorophyll. Adsorbents can cause yield losses—bleaching earth can retain up to one-third of its mass in oil, and K10 montmorillonite and activated carbon recovered only 58 wt% and 46 wt% of the original extract mass, respectively.
  • Hydroprocessing performance: noble metal catalysts generally outperformed base metals, and refined algae oils gave the longest stable performance. NiMo/Al₂O₃ and Pt/Al₂O₃ achieved >60 wt% hydrocarbon yields without significant deactivation within 7 h time on stream (TOS), whereas Ni-based catalysts with algae oils deactivated within 4 h TOS even at 1.3 wt% oil in dodecane. NREL’s Pd/C deoxygenation required 450°C and 1300 psig with hexane dilution, but subsequent Pt/SAPO-11 hydroisomerisation produced renewable diesel blendstocks with cloud points below −10°C.
  • Outlook: no cleanup strategy is universal; hydrolysis to free fatty acids followed by distillation is robust for high-polar-lipid feeds but energy intensive, and integrated process design plus selective extraction solvents are needed.

Methods

  • Narrative review of published literature on SCO lipid recovery, composition, cleanup, and catalytic hydroprocessing; no new experimental data are reported.
  • Compiles lipid content and speciation in Table I and hydroprocessing studies in Table III, covering algae, yeast, bacteria, and terrestrial oils.
  • Qualitative synthesis of catalyst performance, cleanup efficacy, and process tradeoffs across the reviewed studies.

Limitations

  • The paper states that lipid content data should be taken with a grain of salt because analytical methods vary greatly across references, and that TOS in the reviewed literature—less than 200 h—is typically too short to make a meaningful assessment of catalyst tolerance to heteroatoms.
  • The paper notes that all cleanup techniques have drawbacks, few can be expected to apply universally across microbial lipids, many oils are not fully characterised, and extraction protocols can confound downstream performance.
  • Evident from the text: as a narrative review, it lacks a systematic search or meta-analysis, and many tabulated results are reported as N/A or unquantified.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1595/205651321x16024905831259

Cites

103 of 103 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 160 cited sources checked · 0 supported · 0 flagged

  • Premisecitation
    § Lipid Recovery · p. 2

    All these cell wall lysis methods can be scaled up to industrial application.

    “Moreover, all these methods can be scaled up to industrial application (32).”
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    • cites [32] Kruger, 2018, ACS Sustain. Chem. Eng., source

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  • Premisecitation
    § Lipid Recovery · p. 2

    Dilute acid pretreatment is an effective, low cost, energy efficient and scalable means to recover lipids from wet microbial biomass.

    “Researchers at the National Renewable Energy Laboratory (NREL) have shown that dilute acid pretreatment is an effective, low cost, energy efficient and scalable means to recover lipids from wet microbial biomass (31-34).”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [31] Dong, 2016, Appl. Energy, source

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    • cites [32] Kruger, 2018, ACS Sustain. Chem. Eng., source

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    • cites [33] Dong, 2016, Algal Res., source

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    • cites [34] Dong, 2017, Energy Convers. Manag., source

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  • Premisecitation
    § Lipid Recovery · p. 2

    Combinations of hexane with alcohols such as ethanol and isopropanol have the potential to more selectively extract hydrophobic lipids while maintaining high extraction yields.

    “Combinations of hexane with alcohols, such as ethanol and isopropanol, have the potential to more selectively extract hydrophobic lipids while maintaining high extraction yields of these components (31, 39, 40).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [31] Dong, 2016, Appl. Energy, source

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    • cites [39] Wendt, 2020, ACS Sustain. Chem. Eng., source

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    • cites [40] Ryckebosch, 2013, J. Appl. Phycol.,

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  • Interpretationnone given
    § Introduction · p. 2

    Hydroprocessing of single-cell oils requires considerations unique to their differing composition compared to terrestrial oils.

    “hydroprocessing of these oils requires some considerations that are unique to the differing composition of SCOs.”
    Quote in the paperSubstantial claim
  • Interpretationnone given
    § Philip T. Pienkos · p. 1

    Differences in lipid speciation and the presence of co-extracted compounds such as chlorophyll and sterols introduce additional complexities into hydroprocessing of microbial lipids compared to terrestrial oils.

    “While standard hydrotreating catalysts generally perform well with terrestrial oils, differences in lipid speciation and the presence of co-extracted compounds, such as chlorophyll and sterols, introduce additional complexities into the process for microbial lipids.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 49
  • May combine two claims. 42
  • The quote only partly states this claim. 1

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    Interpretationnone given
    § Introduction · p. 2

    Lipid recovery, lipid cleanup, and catalyst selection all appear to play a key role in hydroprocessing performance of single-cell oils.

    “In particular, lipid recovery, lipid cleanup and catalyst selection all appear to play a key role in hydroprocessing performance”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Lipid Recovery · p. 2

    Various cell wall lysis methods have been applied to rupture microbial cells for lipid recovery, including high-pressure homogenisation, bead milling, ultrasound, pulsed electric field, osmotic shock, microwave, subcritical water hydrolysis, enzymatic hydrolysis, autolysis, and chemical hydrolysis.

    “Various cell wall lysis methods have been applied for this application, such as highpressure homogenisation (HPH), bead milling, ultrasound, pulsed electric field (PEF), osmotic shock, microwave, subcritical water hydrolysis, enzymatic hydrolysis, autolysis and chemical hydrolysis (31).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [31] Dong, 2016, Appl. Energy, source

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    Premisecitation
    § Introduction · p. 1

    Oils derived from oleaginous microbes (single-cell oils) have high lipid content (>20%), high growth rate, and can be cultivated on feedstocks or in areas that do not compete for terrestrial food production.

    “Oils derived from oleaginous microbes, such as algae, yeast and bacteria (so-called single-cell oils (SCOs)) have long held promise as a biofuel precursor due to the high lipid content (>20%), high growth rate and the ability of these microbes to be cultivated on feedstocks or in areas that do not compete for terrestrial food production (1).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Martínez, 2015, Int. J. Mol. Sci., source

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    Interpretationreasoning
    § Philip T. Pienkos · p. 1

    Lipid cleanup steps can be introduced to produce suitable feedstocks for catalytic upgrading of single-cell oils.

    “Lipid cleanup steps can be introduced to produce suitable feedstocks for catalytic upgrading.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationnone given
    § Introduction · p. 2

    Production of hydrocarbon fuels from single-cell oils is a growing area of research.

    “However, production of hydrocarbon fuels from SCOs is a growing area of research”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Bleaching · p. 8

    Sathish developed a multi-step process to remove chlorophyll from microalgal crude oil, involving sequential aqueous acid, base and acid treatments to lyse cells, saponify lipids and precipitate chlorophyll, respectively.

    “Sathish developed a multi-step process to remove chlorophyll from microalgal crude oil, involving sequential aqueous acid, base and acid treatments to lyse cells, saponify lipids and precipitate chlorophyll, respectively (73).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73] Sathish, 2012, Bioresour. Technol., source

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    Interpretationreasoning
    § Bleaching · p. 7

    Phosphoric acid bleaching may suffer from yield losses and poor bleaching performance in oils with high levels of phospholipids.

    “However, for the same reason and also because the acid must be washed out of the oil by adding water, phosphoric acid bleaching may suffer from yield losses and poor bleaching performance in oils with high levels of phospholipids.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Degumming · p. 8

    Phosphoric acid is routinely used in algae oil degumming because it also reduces chlorophyll.

    “Phosphoric acid is routinely used in algae oil degumming given the co-benefit of chlorophyll reduction (32, 54, 60).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [32] Kruger, 2018, ACS Sustain. Chem. Eng., source

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    • cites [54] Vamvakaki, 2010, Eng. Life Sci., source

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    • cites [60] Chen, 2012, Bioresour. Technol., source

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    Premisecitation
    § Bleaching · p. 6

    Adsorbents are commonly pretreated with mineral acids to increase the number of exchangeable protons.

    “Adsorbents are commonly pretreated with mineral acids to increase the number of exchangeable protons (66).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [66] Hussin, 2011, Chem. Eng. J., source

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  • May combine two claims.

    Interpretationreasoning
    § Bleaching · p. 7

    The precipitable form of pheophorbide can be easily separated from the oil by filtration while the hydrophobic phytol is preserved.

    “Thus, this precipitable form of pheophorbide can be easily separated from the oil by filtration while the hydrophobic phytol is preserved.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § Lipid Cleanup · p. 6

    When refining single-cell oils for hydrotreating, some modifications to standard vegetable oil refining may be necessary.

    “When refining SCOs for hydrotreating, some modifications may be necessary.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation
    § Degumming · p. 8

    In some SCOs, degumming may be appropriate.

    “Nevertheless, in some SCOs degumming may be appropriate, and examples of both dilute acid and solvent degumming exist in the patent literature (78-80).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Bleaching · p. 7

    Bleaching earths can retain up to a third of their mass in oil, though even higher retentions have been claimed.

    “This is particularly true of bleaching earths, which can retain up to a third of their mass in oil (69), though even higher retentions have been claimed (70).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [69] Kuuluvainen, 2015, J. Chem. Technol. Biotechnol., source

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    • cites [70] Diosady, 2005, Int. J. Appl. Sci. Eng.,

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    Premisecitation
    § Degumming · p. 8

    A drawback of acid degumming is that some decomposed phosphatic acid remains in the oil phase.

    “A drawback of acid degumming, however, is that some decomposed phosphatic acid will remain in the oil phase (76).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [76] Sharma, 2019, Biofuels, Bioprod. Biorefining, source

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    Premisecitation
    § Bleaching · p. 7

    In the comparison, adsorption on silica gel removed 85% of the oil nitrogen content and still showed a detectable chlorophyll signal in UV-vis analysis, while acid bleaching removed 92% of the oil nitrogen and did not show a detectable chlorophyll UV-vis signal.

    “In the comparison, adsorption on silica gel removed 85% of the oil nitrogen content and still showed a detectable chlorophyll signal in UV-vis analysis, while acid bleaching removed 92% of the oil nitrogen and did not show a detectable chlorophyll UV-vis signal.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [72] Kruger, 2017, Energy Fuels, source

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    Premisecitation
    § Degumming · p. 8

    Other degumming methods have been developed to remove these non-hydratable phospholipids.

    “Other degumming methods have been developed to remove these non-hydratable phospholipids (76).”
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    • cites [76] Sharma, 2019, Biofuels, Bioprod. Biorefining, source

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    Interpretationreasoning
    § Bleaching · p. 8

    The process is advantageous in that it does not require anhydrous conditions, but the sequential use of concentrated acids and bases is likely to be expensive and generate highly saline wastewater.

    “The process is advantageous in that it does not require anhydrous conditions, but the sequential use of concentrated acids and bases is likely to be expensive and generate highly saline wastewater.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Bleaching · p. 7

    GCMS analysis of the recovered materials indicated a high content of fatty acids, hydrocarbons and phytol isomers, while UV-vis spectroscopic and ICP analyses revealed complete chlorophyll, phosphorus and magnesium removal.

    “Gas chromatography-mass spectrometry (GCMS) analysis of the recovered materials indicated a high content of fatty acids, hydrocarbons and phytol isomers, while ultraviolet-visible (UV-vis) spectroscopic and inductively coupled plasma (ICP) analyses revealed complete chlorophyll, phosphorus and magnesium removal.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [71] Santillan-Jimenez, 2016, Fuel, source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Bleaching · p. 8

    Roughly 20% of the lipids remained with the biomass solids and another 20% with the precipitated chlorophyll.

    “Though the extraction process was not optimised, roughly 20% of the lipids remained with the biomass solids and another 20% with the precipitated chlorophyll.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73] Sathish, 2012, Bioresour. Technol., source

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    Interpretationreasoning
    § Table I Lipid Content and Speciation in Common Oleaginous Microbes and Terrestrial Plants · p. 5

    While some cleanup of single-cell oils is likely necessary, the most desirable cleanup strategy is not universal across SCOs, and tradeoffs between overall yields and catalyst longevity must be considered.

    “Thus, while some cleanup of the oils is likely necessary, the most desirable cleanup strategy is not universal across SCOs, and tradeoffs between overall yields and catalyst longevity must be considered.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning
    § Lipid Cleanup · p. 6

    Free fatty acids are one of the preferred feeds for hydrotreating, so deodorisation and distillation will not always be needed.

    “For example, FFAs are one of the preferred feeds for hydrotreating so deodorisation and distillation will not always be needed.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given
    § Bleaching · p. 7

    Retaining the phytol in the oil confers the additional benefit of improved biofuel yield and performance due to a high degree of branching.

    “Retaining the phytol in the oil confers the additional benefit of improved biofuel yield and performance due to a high degree of branching.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Degumming · p. 8

    Examples of both dilute acid and solvent degumming exist in the patent literature.

    “Nevertheless, in some SCOs degumming may be appropriate, and examples of both dilute acid and solvent degumming exist in the patent literature (78-80).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [78] Franklin, 2015, Renewable Fuels Produced from Oleaginous Microorganisms

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    • cites [79] Kale, 2012

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    • cites [80] Kale, 2013, Extraction of Polar Lipids by a Two Solvent Method

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    Interpretationreasoning
    § Table I Lipid Content and Speciation in Common Oleaginous Microbes and Terrestrial Plants · p. 5

    Hydrotreating of some contaminants can be beneficial because the high degree of branching (e.g., in terpenes and the phytol chain of chlorophyll) can potentially improve cold flow properties and increase the value of renewable diesel fuel.

    “On the other hand, hydrotreating of some of these contaminants can be beneficial in that the high degree of branching (for example in terpenes and the phytol chain of chlorophyll) can potentially improve cold flow properties and increase the value of the renewable diesel fuel.”
    Quote in the paperNot a substantial claim

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    Premisecitation
    § Bleaching · p. 8

    The purified lipids showed no chlorophyll signal in UV-vis analysis.

    “However, the purified lipids showed no chlorophyll signal in UV-vis analysis.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73] Sathish, 2012, Bioresour. Technol., source

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    Interpretationreasoning
    § Lipid Cleanup · p. 6

    In some cases it may be advantageous to hydrolyse the entire lipid stream to free fatty acids, distil these FFAs away from impurities, and route the distillate to hydrotreating.

    “However, in some cases it may be advantageous to hydrolyse the entire lipid stream to FFAs, distil these FFAs away from impurities, and route the distillate to hydrotreating.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisereasoning
    § Bleaching · p. 7

    The relative abundance of hydrocarbons in the activated carbon-bleached material was lower than in the K10-bleached material, likely due to the greater hydrophobicity of the activated carbon retaining more of the hydrocarbons.

    “Notably, the relative abundance of hydrocarbons in the activated carbon-bleached material was lower than in the K10-bleached material, likely due to the greater hydrophobicity of the activated carbon retaining more of the hydrocarbons.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [71] Santillan-Jimenez, 2016, Fuel, source

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  • May combine two claims.

    Premisecitation
    § Degumming · p. 8

    These species complex with metal cations and cannot be removed by conventional water degumming processes that precipitate hydratable phospholipids.

    “These species complex with metal cations and cannot be removed by conventional water degumming processes that precipitate hydratable phospholipids.”
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    • cites [75] Paisan, 2017, J. Environ. Chem. Eng., source

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    Interpretationcitation
    § Bleaching · p. 7

    Increasing adsorbent loading, while effective in reducing chlorophyll content, decreases yields due to co-adsorption of lipids.

    “Increasing adsorbent loading, while effective in reducing chlorophyll content, decreases yields due to co-adsorption of lipids.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Bleaching · p. 7

    Phosphoric acid-catalysed dealkylation was originally developed by Diosady to refine Canadian canola oil, which has anomalously high chlorophyll content for a terrestrial oil due to weather conditions in the region.

    “Phosphoric acid-catalysed dealkylation was originally developed by Diosady to refine Canadian canola oil, which has anomalously high chlorophyll content for a terrestrial oil due to weather conditions in the region (70).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [70] Diosady, 2005, Int. J. Appl. Sci. Eng.,

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    Interpretationreasoning
    § Lipid Cleanup · p. 6

    In these cases, bleaching and degumming may not be needed.

    “In these cases, bleaching and degumming may not be needed.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 9

    The thermochemical pretreatment reduced the amount of phosphorus and iron in the Chlorella oil by nearly 100%, while sulfur was only reduced by 30%.

    “Notably, this pretreatment reduced the amount of phosphorus and iron in the Chlorella oil by nearly 100%, while sulfur was only reduced by 30%.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [83] Lawal, 2015, “Pt-Based Bi-Metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil”

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    • cites [106] Czartoski

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    Premiseown data
    § Hydroprocessing of Single Cell Oils · p. 9

    Hydroprocessing approaches and cleanup approaches for use on algae oils have varied significantly.

    “Hydroprocessing approaches and cleanup approaches for use on algae oils have varied significantly, though many employed techniques to specifically remove chlorophyll.”
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    • cites Table III

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    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 9

    The N. salina oil had up to 0.8% chlorophyll, 0.5% carotenoids, 5% sterols, 1-5% mannitol and a large fraction of unidentified unsaponifiable matter.

    “Analysis showed that the oil had up to 0.8% chlorophyll, 0.5% carotenoids, 5% sterols, 1-5% mannitol and a large fraction of unsaponifiable matter that was not identified (83).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [83] Lawal, 2015, “Pt-Based Bi-Metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil”

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    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 9

    The oils used by Lawal and coworkers were obtained from Valicor, which employed a thermochemical pretreatment of algal biomass to render the lipids extractable.

    “The oils were obtained from Valicor, which employed a thermochemical pretreatment of the algal biomass to render the lipids extractable (83, 106).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [83] Lawal, 2015, “Pt-Based Bi-Metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil”

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    • cites [106] Czartoski

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    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 9

    Many hydroprocessing approaches for algae oils employed techniques to specifically remove chlorophyll.

    “Hydroprocessing approaches and cleanup approaches for use on algae oils have varied significantly, though many employed techniques to specifically remove chlorophyll.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Table III

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  • May combine two claims.

    Premisecitation
    § Hydrolysis and Distillation · p. 8

    Higher temperatures can significantly shorten the reaction time, for example to about 10 min, but also significantly increase the operating pressure, for example to about 2500 psig.

    “Higher temperatures can significantly shorten the reaction time (for example to ~10 min), but also significantly increase the operating pressure (for example to ~2500 psig) (82).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [82] Coppola, 2018, ‘Hydrothermal Cleanup Process’

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    Interpretationcitation
    § Degumming · p. 8

    For SCO streams containing large fractions of polar lipids, hydrolysis to a FFA stream is likely preferable for fuel production.

    “For SCO streams containing large fractions of polar lipids, hydrolysis to a FFA stream is likely preferable for fuel production (34).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Dong, 2017, Energy Convers. Manag., source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Hydrolysis and Distillation · p. 8

    Lawal et al. demonstrated the effectiveness of hydrolysing algal lipids to FFAs and distilling the hydrolysed FFAs away from impurities.

    “Lawal et al . demonstrated the effectiveness of hydrolysing algal lipids to FFAs and distilling the hydrolysed FFAs away from impurities (83).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [83] Lawal, 2015, “Pt-Based Bi-Metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil”

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 9

    Hydroprocessing of yeast oils has been reported by a few researchers.

    “Hydroprocessing of yeast oils, which do not contain chlorophyll but may contain sterols, has also been reported by a few researchers.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Table III

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    Premisenone given
    § Hydroprocessing of Single Cell Oils · p. 9

    Among other microbes, only lipids from the methanotrophic bacterium Methylomicrobium buryatense have been upgraded to hydrocarbons.

    “Among other microbes, to our knowledge only lipids from the methanotrophic bacterium Methylomicrobium buryatense have been upgraded to hydrocarbons.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Table III

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    Premisecitation
    § Hydrolysis and Distillation · p. 8

    Steam splitting via the Colgate-Emery process is the current industrial standard, employing temperatures of 250-330°C and reaction times of 2-3 h.

    “Steam splitting via the Colgate-Emery process is the current industrial standard, employing temperatures of 250-330°C and reaction times of 2-3 h (81).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [81] Barnebey, 1948, J. Am. Oil Chem. Soc., source

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    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 9

    The lipids used by Crocker and co-workers were purified by column chromatography using either K10 montmorillonite clay or activated carbon with silica gel.

    “the lipids were purified by column chromatography using either K10 montmorillonite clay or activated carbon with silica gel, which was effective at removing chlorophyll and other pigments, magnesium and phosphorus.”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [71] Santillan-Jimenez, 2016, Fuel, source

      Not checked in the free run.

    • cites [89] Loe, 2016, Appl. Catal. B: Environ., source

      Not checked in the free run.

    • cites [90] Santillan-Jimenez, 2015, Catal. Today, source

      Not checked in the free run.

    • cites [91] Wilson, 2014, Appl. Petrochem. Res., source

      Not checked in the free run.

  • May combine two claims.

    Premisenone given
    § Hydroprocessing of Single Cell Oils · p. 9

    K10 montmorillonite appeared to be a more effective adsorbent than activated carbon, resulting in a greater fraction of products in the diesel range.

    “K10 montmorillonite appeared to be a more effective adsorbent than activated carbon, resulting in a greater fraction of products in the diesel range.”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [71] Santillan-Jimenez, 2016, Fuel, source

      Not checked in the free run.

    • cites [89] Loe, 2016, Appl. Catal. B: Environ., source

      Not checked in the free run.

    • cites [90] Santillan-Jimenez, 2015, Catal. Today, source

      Not checked in the free run.

    • cites [91] Wilson, 2014, Appl. Petrochem. Res., source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 9

    A more detailed analysis of impurities suggested that the oil cleanup quantitatively removed phosphorus and magnesium, though a small amount of nitrogen remained.

    “A more detailed analysis of impurities also suggested that the oil cleanup quantitatively removed phosphorus and magnesium, though a small amount of nitrogen remained (71).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [71] Santillan-Jimenez, 2016, Fuel, source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 13

    Molybdenum nitride catalysts had much lower initial activity than nickel-based catalysts but did not show as strong a deactivation as nickel catalysts.

    “while molybdenum nitride catalysts had much lower initial activity than nickel-based catalysts, the molybdenum nitride catalysts did not show as strong a deactivation as the nickel catalysts did (95)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [95] Nguyen, 2017, J. Chem. Technol. Biotechnol., source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 13

    Low conversion of FFA and acylglycerides was observed, and no conversion of sterols or steryl esters was found.

    “While low conversion of the FFA and acylglycerides was observed, no conversion of the sterols or steryl esters was found (96)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [96] Nguyen, 2016, Ind. Eng. Chem. Res., source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 9

    Residual extraction solvent, namely chloroform, was likely the source of chloride detected on the catalyst in post-reaction analysis.

    “Santillan-Jimenez et al . (71) also noted that the residual extraction solvent (namely chloroform) was likely the source of chloride detected on the catalyst in post-reaction analysis (71), underscoring the observation that the extraction protocol can impact downstream processes through routes other than influencing the types of lipids extracted.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [71] Santillan-Jimenez, 2016, Fuel, source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 13

    FFAs were the major product, with acylglycerides featured prominently, in deoxygenation of Chlorella algae oil over Ni and Mo catalysts.

    “FFAs were the major product, with acylglycerides featured prominently as well”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [95] Nguyen, 2017, J. Chem. Technol. Biotechnol., source

      Not checked in the free run.

    • cites [96] Nguyen, 2016, Ind. Eng. Chem. Res., source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 13

    The crude extracted lipids comprised only around 50% fatty acids and 3-4% sterols, with the remainder unidentified.

    “the crude extracted lipids comprised only around 50% fatty acids and 3-4% sterols, with the remainder unidentified (95)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [95] Nguyen, 2017, J. Chem. Technol. Biotechnol., source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 15

    The high degree of polar head group cleavage was confirmed by the presence of only 4 ppm phosphorus in the oil, though the oil contained sulfur, nitrogen, sodium and halogens in higher amounts.

    “The high degree of polar head group cleavage was confirmed by the presence of only 4 ppm phosphorus in the oil, though the oil contained sulfur, nitrogen, sodium and halogens in higher amounts”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Dong, 2017, Energy Convers. Manag., source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 15

    The yeast lipids contained a small amount of steryl esters and a significant amount of polar lipids.

    “The lipids were found to contain a small amount of steryl esters and a significant amount of polar lipids as well”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [10] Sànchez i Nogué, 2018, Green Chem., source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 15

    The catalytic cracking experiments with yeast lipid from Metschkownia pulcherrima included 9 wt% sterols.

    “the catalytic cracking experiments were performed with a yeast lipid from Metschkownia pulcherrima that included 9 wt% sterols”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [107] Wagner, 2014, Fuel, source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 14

    Poddar et al. achieved nearly complete conversion to alkanes and nearly 80% yield to liquid-phase products in 6 h at 375°C and 50 bar hydrogen over a phosphorus-promoted CoMo/Al2O3 catalyst.

    “achieving nearly complete conversion to alkanes and nearly 80% yield to liquid-phase products in 6 h at 375°C and 50 bar hydrogen (103)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [103] Poddar, 2018, Biomass Bioenergy, source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 14

    Dichloromethane:methanol was the highest yielding solvent on a weight basis for extracting Scenedesmus algae oil, but the primary components were sterols and tocopherols rather than acylglycerides and FFAs.

    “Dichloromethane:methanol was the highest yielding solvent on a weight basis, but the primary components were sterols and tocopherols rather than acylglycerides and FFAs”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [102] Tang, 2019, Green Chem., source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § Summary and Outlook · p. 15

    The variety of techniques and solvents used to extract lipids may co-extract different undesirable components.

    “The situation is additionally confounded by the variety of techniques and solvents used to extract the lipids, which may co-extract different undesirable components”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Summary and Outlook · p. 15

    Industrial processes producing green diesel fuels from vegetable oils employ nickel-molybdenum or cobalt-molybdenum sulfide catalysts similar to those used in petroleum refining.

    “industrial processes producing green diesel fuels from vegetable oils, such as HoneywellUOP's Ecofining, Neste's NExBTL, Axens' Vegan and Renewable Energy Group's Bio-Synfining processes employ nickel-molybdenum or cobalt-molybdenum sulfide catalysts similar to those used in petroleum refining (111)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [111] Zhang, 2018, BioEnergy Res., source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 14

    With the large-pore Pt/USY zeolite catalyst, isomerisation and cracking were competitive, resulting in a 40% or more mass loss to naphtha-range hydrocarbons.

    “With the large-pore Pt/USY zeolite catalyst, isomerisation and cracking were competitive, resulting in a 40% or more mass loss to naphtha-range hydrocarbons”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [98] Robota, 2013, Energy Fuels, source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationnone given
    § Summary and Outlook · p. 15

    Times on stream in the literature reviewed here, less than 200 h TOS, have typically been too short to make a meaningful assessment of noble metal tolerance.

    “times on stream in the literature reviewed here, less than 200 h TOS, have typically been too short to make a meaningful assessment”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 14

    After 6 h at 290°C and 440 psig hydrogen, 67% of the algae oil was converted to both saturated and unsaturated alcohols and hydrocarbons over a nanoparticle iron catalyst.

    “After 6 h at 290°C and 440 psig hydrogen, 67% of the algae oil had been converted to both saturated and unsaturated alcohols and hydrocarbons”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [101] Kandel, 2014, J. Catal., source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 14

    Hydrogen-free decarboxylation of Chlorella oil at 330-370°C for 2 h increased the heating value and carbon content of the organic phase and produced significantly isomerised compounds.

    “The heating value and carbon content of the organic phase both increased and the organic product contained significantly isomerised compounds”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [100] Fu, 2015, Fuel, source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 14

    The two most promising streams gave relatively low conversion but high isomerisation selectivity over the Pt/CaY catalyst.

    “The two most promising streams gave relatively low conversion, but high isomerisation selectivity over the Pt/CaY catalyst”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [105] Schulz, 2018, Sustain. Energy Fuels, source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 15

    Preliminary catalyst screening with nickel- and copper-based catalysts confirmed that these catalysts would be rapidly deactivated in the presence of phosphorus-containing feeds, while noble metals performed better.

    “a preliminary catalyst screening with nickel- and copper-based catalysts confirmed the hypothesis that these catalysts would be rapidly deactivated in the presence of phosphorus-containing feeds, while noble metals performed better”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Dong, 2017, Energy Convers. Manag., source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation
    § Summary and Outlook · p. 15

    Noble metals may have environmental advantages (at least for ruthenium and platinum), and some of the cost can be recouped by regeneration and recycling of spent catalysts.

    “there may be environmental advantages (at least for metals such as ruthenium and platinum) (109), and some of the cost can be recouped by regeneration and recycling of the spent catalysts (110)”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [109] Bystrzanowska, 2019, ACS Sustain. Chem. Eng., source

      Not checked in the free run.

    • cites [110] Marafi, 2017, Energy Fuels, source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § Summary and Outlook · p. 15

    Supported noble metals may be able to tolerate some degree of phosphorus, nitrogen and sulfur in the feedstock.

    “it is tempting to infer that supported noble metals may even be able to tolerate some degree of phosphorus, nitrogen and sulfur in the feedstock”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Hydroprocessing of Single Cell Oils · p. 14

    Other solvents were lower yielding for extracting Scenedesmus algae oil.

    “Other solvents were lower yielding”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [102] Tang, 2019, Green Chem., source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationreasoning
    § Summary and Outlook · p. 16

    In lipid streams with high polar lipid content, hydrolysis to FFAs may prove more economical.

    “In lipid streams with high polar lipid content, hydrolysis to FFAs may prove more economical”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § Summary and Outlook · p. 16

    Degumming and phosphoric acid bleaching can work well for lipid streams low in polar lipids, but would suffer significant yield losses otherwise, and phosphoric acid must be thoroughly washed out.

    “Degumming (precipitation of phospholipids) and phosphoric acid bleaching can work well for lipid streams that are low in polar lipids, but would suffer from significant yield losses otherwise, and the phosphoric acid must be thoroughly washed out of the cleaned lipid stream to avoid contamination from the bleaching agent”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Summary and Outlook · p. 15

    Nickel-molybdenum catalysts tend to leach sulfur into the product, which may inhibit their ability to meet increasingly stringent sulfur limits in fuels.

    “these catalysts tend to leach sulfur into the product (21), which may inhibit the ability of these catalysts to meet increasingly stringent sulfur limits in fuels”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] Kubička, 2011, Appl. Catal. A: Gen., source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning
    § Summary and Outlook · p. 16

    SCOs are poised to make a significant impact in sustainable fuel production.

    “SCOs are poised to make a significant impact in sustainable fuel production”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Interpretationnone given
    § Summary and Outlook · p. 16

    The advent of third generation cellulosic sugars may spur further development of heterotrophic oleaginous microbes.

    “the advent of third generation cellulosic sugars may spur further development of heterotrophic oleaginous microbes as well”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given
    § Summary and Outlook · p. 16

    The lipid hydrolysis step can be integrated with the biomass pretreatment or cell wall rupture step to simultaneously rupture cell walls for bulk oil extraction and liberate FFA from polar lipids.

    “the lipid hydrolysis step can be integrated with the biomass pretreatment or cell wall rupture step to simultaneously rupture the cell walls for bulk oil extraction and liberate FFA from polar lipids”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationnone given
    § Summary and Outlook · p. 16

    Methyl esterification and distillation should be similarly effective, but methanol would need to be recovered for high material and economic efficiency, or else recovered as methane after hydrotreating.

    “Methyl esterification and distillation should be similarly effective, but the methanol would need to be recovered for high material and economic efficiency, or else recovered as methane after hydrotreating”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § Summary and Outlook · p. 16

    Saponification of the lipid stream to FFA followed by distillation is perhaps the most robust as it should be effective even with lipid feeds containing high levels of polar lipids, sterols, chlorophyll and metals.

    “Saponification of the lipid stream to FFA followed by distillation is perhaps the most robust as it should be effective even with lipid feeds containing high levels of polar lipids, sterols, chlorophyll and metals”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Summary and Outlook · p. 15

    At least one evaluation concluded that decarboxylation would be economically favourable, provided that hydrogen consumption through subsequent methanation and reverse water-gas shift reactions is not significant.

    “At least one evaluation of the tradeoffs between carbon yield and hydrogen consumption concluded that decarboxylation would be economically favourable, provided that hydrogen consumption through subsequent methanation and reverse water-gas shift reactions is not significant (112)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [112] Donnis, 2009, Top. Catal., source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Summary and Outlook · p. 15

    These catalysts tend to favour hydrodeoxygenation over decarbonylation or decarboxylation, which preserves carbon in the product but also consumes more hydrogen.

    “These catalysts tend to favour hydrodeoxygenation over decarbonylation or decarboxylation, which preserves carbon in the product, but also consumes more hydrogen in the process”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [111] Zhang, 2018, BioEnergy Res., source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § Summary and Outlook · p. 15

    Nickel-molybdenum catalysts are frequently employed for hydrodesulfurisation and hydrodenitrogenation, which may indicate a higher level of robustness to heteroatoms than other types of catalysts.

    “Nickel-molybdenum catalysts are also frequently employed for hydrodesulfurisation and hydrodenitrogenation, which may indicate a higher level of robustness to heteroatoms than other types of catalysts”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationnone given
    § Summary and Outlook · p. 16

    The distillation step is energy intensive compared to most other bleaching methods and the cost of the alkali is high.

    “the distillation step is energy intensive compared to most of the other bleaching methods and the cost of the alkali is high”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning
    § Summary and Outlook · p. 16

    Converting microbial lipids to fuels is a promising approach to displace conventional fossil fuels, especially for diesel and jet fuels which share the same carbon number range as the microbial lipids.

    “converting microbial lipids to fuels is a promising approach to displace conventional fossil fuels, especially for diesel and jet fuels which share the same carbon number range as the microbial lipids”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § Summary and Outlook · p. 16

    Lipid stream cleanup by a number of approaches appears promising, but all techniques have drawbacks and only a few can be reasonably expected to apply universally across microbial lipids.

    “lipid stream cleanup by a number of approaches appears promising, but all of the techniques have some drawbacks and only a few can be reasonably expected to apply universally across microbial lipids”
    Quote in the paperNot a substantial claim
80 of 80

  • The paper relies on this without support.

    Standard hydrotreating catalysts generally perform well with terrestrial oils.

    “While standard hydrotreating catalysts generally perform well with terrestrial oils”

  • The paper relies on this without support.

    In most cases, single-cell oils are produced intracellularly, necessitating separation from other cell components prior to upgrading.

    “In most cases, SCOs are produced intracellularly, and thus necessitate separation from the other cell components prior to upgrading.”

  • The paper relies on this without support.

    Microbial biomass is typically recovered with a very high water content (≥80%) relative to terrestrial biomass.

    “Additionally, the microbial biomass is typically recovered with a very high water content ( ≥ 80%) relative to terrestrial biomass.”

  • The paper relies on this without support.

    While vegetable oils can be effectively extracted by pressing, solvent extraction or a combination thereof, these operations are usually not effective when applied directly to microbial biomass.

    “Thus, while vegetable oils can be effectively extracted by pressing, solvent extraction or a combination thereof, these operations are usually not effective when applied directly to microbial biomass.”

  • The paper relies on this without support.

    It is energy intensive to dehydrate microbial biomass.

    “Furthermore, it is energy intensive to dehydrate microbial biomass”

  • The paper relies on this without support.

    The first step in lipid recovery is commonly to rupture the microbial cell wall to allow access to the lipids.

    “The first step is commonly to rupture the microbial cell wall which allows access to the lipids.”

  • The paper relies on this without support.

    Hexane is a commonly employed extraction solvent, but does not always maximise extraction yields.

    “For example, hexane is a commonly employed extraction solvent, but does not always maximise extraction yields.”

  • The paper relies on this without support.

    Incorporation of a polar solvent often leads to more prevalent co-extraction of other polar materials, such as polar lipids, pigments, proteins and sterols, that require more severe cleanup of the lipid phase.

    “However, incorporation of a polar solvent also often leads to more prevalent co-extraction of other polar materials, such as polar lipids, pigments, proteins and sterols, that require more severe cleanup of the lipid phase.”

  • The paper relies on this without support.

    Other components are often detrimental in catalytic hydroprocessing as they either increase hydrogen consumption due to a high degree of unsaturation, contain heteroatoms that can poison metal or acid catalysts, or contribute to poor cold flow properties.

    “Other components are often detrimental in catalytic hydroprocessing as they either increase hydrogen consumption due to a high degree of unsaturation (for example terpenes, carotenoids and chlorophyll), contain heteroatoms that can poison metal or acid catalysts (for example polar lipids and chlorophyll) or contribute to poor cold flow properties (for example sterol-derived cycloparaffins).”

  • The paper relies on this without support.

    Cleanup of single-cell oils targets many of the same impurities that are removed in refining of vegetable oils for human consumption, and thus cleanup approaches can be broadly categorised into the same four operations: bleaching, degumming, deodorisation and distillation.

    “Cleanup of SCOs targets many of the same impurities that are removed in refining of vegetable oils for human consumption, and thus cleanup approaches can be broadly categorised into the same four operations: bleaching to remove pigments and polar compounds, degumming to precipitate phospholipids, deodorisation to remove FFAs and distillation to remove additional FFAs and other volatile matter.”

  • The paper relies on this without support.

    Crude extracted oils from autotrophically-grown microbes are often high in chlorophyll content.

    “Crude extracted oils from autotrophically-grown microbes are often high in chlorophyll content.”

  • The paper relies on this without support.

    The two most common approaches to remove chlorophyll are adsorption on a solid material and dealkylation via acid treatment.

    “The two most common approaches to remove chlorophyll are adsorption on a solid material and dealkylation via acid treatment.”

  • The paper relies on this without support.

    Bleaching earths, activated carbon and silica are common adsorbents for oil refining.

    “Bleaching earths, activated carbon and silica are common adsorbents for oil refining.”

  • The paper relies on this without support.

    The acid bleaching approach employs anhydrous acids, such as phosphoric acid or sulfuric acid, to cleave the phytol side chain from the porphyrin structure, the latter of which is not soluble in oil.

    “The acid bleaching approach employs anhydrous acids, such as phosphoric acid or sulfuric acid to cleave the phytol side chain from the porphyrin structure, the latter of which is not soluble in oil.”

  • The paper relies on this without support.

    Single-cell oils can have higher phospholipid content than most terrestrial oils, and removal of these polar lipids is necessary to prevent catalyst fouling in downstream processes.

    “Analogous to chlorophyll, SCOs can have higher phospholipid content than most terrestrial oils, and removal of these polar lipids is necessary to prevent catalyst fouling in downstream processes.”

  • The paper relies on this without support.

    Drying microbial biomass is much more energy intensive than drying terrestrial crops.

    “Drying of microbial biomass is much more energy intensive than drying terrestrial crops, and may be economically untenable for fuel production.”

  • The paper relies on this without support.

    The transesterification approach requires a dry feedstock.

    “However, this approach suffers from two significant drawbacks, namely that it requires a dry feedstock and that it consumes methanol stoichiometrically.”

  • The paper relies on this without support.

    The transesterification approach consumes methanol stoichiometrically.

    “However, this approach suffers from two significant drawbacks, namely that it requires a dry feedstock and that it consumes methanol stoichiometrically.”

  • The paper relies on this without support.

    Base metals such as nickel, molybdenum and copper are more prone to coking, oxidation by feedstock oxygen and poisoning by feedstock heteroatom impurities than noble metals.

    “base metals such as nickel, molybdenum and copper are more prone to coking, oxidation by feedstock oxygen and poisoning by feedstock heteroatom impurities”

  • The paper relies on this without support.

    Nickel-molybdenum catalysts typically require a co-fed source of sulfur, often hydrogen sulfide or dimethyl disulfide, to mitigate conversion of the active sulfide phase to a less-active oxide.

    “nickel-molybdenum catalysts typically require a co-fed source of sulfur, often hydrogen sulfide or dimethyl disulfide, to mitigate conversion of the active sulfide phase to a less-active oxide”

  • The paper relies on this without support.

    The deployment of large-scale wind and solar power can produce excess low-cost electricity for water electrolysis to produce inexpensive hydrogen.

    “the deployment of largescale wind and solar power has at times resulted in excess power production and low-cost electricity that can be used for water electrolysis to produce inexpensive hydrogen”

  • The paper relies on this without support.

    Hexane extraction can result in low extraction yields and form emulsions with wet biomass.

    “Hexane is the simplest solvent employed, but can result in low extraction yields and form emulsions with wet biomass”

  • The paper relies on this without support.

    Alcohols such as methanol and ethanol can increase extraction yields and minimise emulsions, but can also increase coextraction of impurities.

    “Alcohols, such as methanol and ethanol can be added to increase the extraction yields and minimise emulsions, but can also increase coextraction of impurities”
23 of 23

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Technologies around hydrotreatment have been developed which aim to reduce the number of double bonds in the starting material and remove the O atoms in the carboxyl end of the molecule through decarboxylation/decarbonylation.

    “In order to decrease the oxygen content in natural fatty acids and their derivatives technologies around hydrotreatment have been developed which aim to reduce the number of double bonds in the starting material and remove the O atoms in the carboxyl end of the molecule through decarboxylation/decarbonylation [118] (Figure 11).”

    From Key Targets for Improving Algal Biofuel Production (2021) · cites this paper as [118]

    The paper describes decarboxylation of free fatty acids during deoxygenation (Hydroprocessing of Single Cell Oils, p. 14) and treats decarbonylation as another deoxygenation pathway (Summary and Outlook, p. 15). It also links unsaturated products to possibly insufficient hydrogen (p. 14), but does not explicitly state that these technologies aim to reduce double bonds in the starting material. The claim also omits hydrodeoxygenation, which the paper identifies as an alternative to decarboxylation and decarbonylation. (LLM, conf=0.82)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Minimum alkane yield differs between text and table

    Minor

    For the Synechocystis study, the text gives a minimum alkane yield of 33%, while Table III gives 32%.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 5

  1. Ryckebosch, 2013, J. Appl. Phycol.,, 26, 1501
  2. Gema, 2002, Appl. Microbiol. Biotechnol.,, 58, 303
  3. Ahmed, 2006, Food Technol. Biotechnol.,, 44, 283
  4. Diosady, 2005, Int. J. Appl. Sci. Eng.,, 3, 81
  5. Zufarov, 2008, Acta Chim. Slovaca,, 1, 321–

Cited by

Sorted by citations

Related

Authors
Kruger, J. S., Knoshaug, E. P., Dong, T., Hull, T. C., & Pienkos, P. T.
Affiliations
National Laboratory of the Rockies (US)
Corresponding author
Kruger, Jacob S.
ORCID
Venue
Johnson Matthey Technology Review
Publisher
Johnson Matthey Plc
Published
2021-04-01
Volume
65
Issue
2
Pages
227-246
ISSN
2056-5135 (ISSN-L)
DOI
10.1595/205651321x16024905831259
OpenAlex
W3134476988
Semantic Scholar
42b07489b59b4553791fc0c7eb7b05b22cf251e6
Cited by
10
References
103
Citations by year
2026: 1 · 2025: 4 · 2024: 2 · 2023: 1 · 2022: 1 · 2021: 1
FWCI
0.37
Type
journal article
Language
en
Open access
Licence
cc-by-nc-nd
Locations
  • Johnson Matthey Technology Review (publishedVersion, cc-by-nc-nd)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
Funders
  • U.S. Department of Energy (DE -AC36-08GO28308, No. DE-AC36-08GO28308, 08GO28308, Contract No. DE-AC36-08GO28308, AC36‐08GO28308)
  • National Renewable Energy Laboratory (Contract No. DE-AC36-08GO28308, DE-AC36-08-GO28308, AC36-08GO28308)
Topics
  • Physical Sciences › Engineering › Mechanical Engineering › Catalysis and Hydrodesulfurization Studies
  • Physical Sciences › Chemical Engineering › Catalysis › Catalysts for Methane Reforming
  • Physical Sciences › Engineering › Biomedical Engineering › Biodiesel Production and Applications
Keywords
catalytic hydroprocessing, microbial lipids, single cell oil, renewable diesel, hydrotreating catalysts, chlorophyll, sterols, oleaginous microorganisms, biofuel precursors

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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