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Cited by 68Thermochemical Biomass Conversion ProcessesThermal and Kinetic AnalysisBiofuel production and bioconversion

Thermal Analysis Technologies for Biomass Feedstocks: A State-of-the-Art Review

Open access
Teh, Jun Sheng, Teoh, Yew Heng, How, Heoy Geok, Sher, Farooq·2021·Processes
DOI 10.3390/pr9091610
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Abstract

An effective analytical technique for biomass characterisation is inevitable for biomass utilisation in energy production. To improve biomass processing, various thermal conversion methods such as torrefaction, pyrolysis, combustion, hydrothermal liquefaction, and gasification have been widely used to improve biomass processing. Thermogravimetric analysers (TG) and gas chromatography (GC) are among the most fundamental analytical techniques utilised in biomass thermal analysis. Thus, GC and TG, in combination with MS, FTIR, or two-dimensional analysis, were used to examine the key parameters of biomass feedstock and increase the productivity of energy crops. We can also determine the optimal ratio for combining two separate biomass or coals during co-pyrolysis and co-gasification to achieve the best synergetic relationship. This review discusses thermochemical conversion processes such as torrefaction, combustion, hydrothermal liquefaction, pyrolysis, and gasification. Then, the thermochemical conversion of biomass using TG and GC is discussed in detail. The usual emphasis on the various applications of biomass or bacteria is also discussed in the comparison of the TG and GC. Finally, this study investigates the application of technologies for analysing the composition and developed gas from the thermochemical processing of biomass feedstocks.

AI snapshot

Written from the paper’s full text.

TL;DR

This state-of-the-art review surveys thermochemical conversion routes for biomass and the thermal analysis technologies used to characterize feedstocks and products, especially TG, GC, DSC, and their hyphenated variants. It concludes that GC and TGA remain the most commonly used methods despite flaws, while GC×GC and advanced data processing can improve resolution of complex product mixtures.

Key findings

  • The review compares five thermochemical routes: gasification (500–1300 °C, ≥0.1 MPa), pyrolysis (300–1000 °C, 0.1–0.5 MPa), combustion (700–1000 °C, ≥0.1 MPa), torrefaction (200–300 °C, ≥0.1 MPa), and hydrothermal liquefaction (250–550 °C, 5–25 MPa).
  • Torrefaction is described as producing a coal-like solid; the review reports that about 70% of original biomass weight and 90% of original biomass energy are recovered, while 30% of weight and 10% of energy are discharged as liquids and gases.
  • Pyrolysis regimes are distinguished by heating rate and temperature: slow pyrolysis (<1 °C/s, 300–700 °C, >450 s), fast pyrolysis (500–1250 °C, 10–300 °C/s, 0.5–200 s), and flash pyrolysis (>1000 °C/s, 800–1300 °C, <0.5 s).
  • TGA is reported as a low-cost, small-sample method with commercial instruments covering up to 1000 °C, balance sensitivity of 0.1 µg, and heat-up rates from 0.1 to 200 °C/min; DSC is used for HTC enthalpy, with the review citing an enthalpy change on the order of 1 MJ per 1 kg dry biomass.

Methods

  • Design: narrative state-of-the-art review of thermochemical conversion processes and thermal analysis technologies, including TG, GC, DSC, TGA-FTIR, TGA-MS, Py-GC-MS, TGA-GC-MS, and GC×GC-MS.
  • Data: synthesizes prior literature and tabulates biomass feedstocks, instruments, chromatographic/TGA/DSC conditions, and reported findings; no primary experimental dataset is generated.
  • Analysis: qualitative comparison of process conditions, product compositions, analytical advantages/limitations, and applications, supported by summary tables and schematic figures.

Limitations

  • Stated in the paper: Py-GC-MS cannot continuously execute a procedure and cannot aggregate formulated mixtures of reaction components; GC-MS can leave many chromatographic peaks unidentified; TG-MS is limited to 300 amu, requires prior dataset knowledge, and can suffer inlet obstruction by big molecules; FTIR is less sensitive than MS or GC-MS.
  • Evident from the text: the review does not report a systematic search strategy, inclusion criteria, or quantitative meta-analysis, so its coverage and conclusions are narrative rather than systematic.
  • Evident from the text: the manuscript contains duplicated passages, garbled table/figure text, and off-topic content on cement hydration, which weakens confidence in the review’s editorial consistency.

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

Integrity signals

Registry

Crossref · 10.3390/pr9091610

Cites

131 of 131 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 37 cited sources checked · 0 supported · 0 flagged

  • Findingcitation

    The energy-to-weight ratio of hydrochar is higher than that of the initial material.

    “The energy-to-weight ratio of hydro char is higher than that of the initial material [63].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [63] Ischia, 2021, Hydrothermal Carbonization of Organic Waste and Biomass: A Review on Process, Reactor, and Plant Modeling, Waste Biomass Valorization source

      Not checked in the free run.

  • Findingcitation

    Py-GC-MS does not allow for the aggregation of formulated mixtures of reaction components, which are only collected for a short time in the adsorption column before being passed to the gas chromatograph for analysis.

    “Furthermore, Py-GC-MS does not allow for the aggregation of formulated mixtures of reaction components, which are only collected for a short time in the adsorption column before being passed to the gas chromatograph for analysis [72].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [72] Grams, 2020, Chromatographic analysis of bio-oil formed in fast pyrolysis of lignocellulosic biomass, Rev. Anal. Chem. source

      Not checked in the free run.

  • Premisecitation

    The thermochemical pyrolysis process works well in the absence of oxygen at temperatures between 350 and 550 °C.

    “The thermochemical pyrolysis process works well in the absence of oxygen at temperatures between 350 and 550 • C [34].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Sebastiani, 2021, Steam—oxygen gasification of refuse derived fuel in fluidized beds: Modelling and pilot plant testing, Fuel Process. Technol. source

      Not checked in the free run.

  • Premisecitation

    Thermal results can be combined with knowledge about the chemical origin, shape, and composition of material using TGA-GC-MS.

    “Thermal results can be combined with knowledge about the chemical origin, shape, and composition of material using this mixture of methods [74].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [74] Dupont, 2018, Impact of biomass diversity on torrefaction: Study of solid conversion and volatile species formation through an innovative TGA-GC/MS apparatus, Biomass Bioenergy source

      Not checked in the free run.

  • Interpretationnone given

    The benefit of hydrothermal carbonisation is that biomass can be converted to carbonaceous solids without an energy-intensive drying process.

    “The benefit of hydrothermal carbonisation is that biomass can be converted to carbonaceous solids without the need for an energy-intensive drying process.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. 35
  • May combine two claims. 19

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

    Findingcitation

    TGA-IST16-GC-MS is faster and easier to conduct than conventional methods of extracting copolymer compositions, such as nuclear magnetic resonance or temperature-escalating elution fractionation (TREF).

    “It is faster and easier to conduct than conventional methods of extracting copolymer compositions, such as nuclear magnetic resonance or temperature-escalating elution fractionation (TREF) [76].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [76] Boyron, 2019, An Advanced Technique for Linear Low-Density Polyethylene Composition Determination: TGA–IST16–GC–MS Coupling, Macromol. Chem. Phys. source

      Not checked in the free run.

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

    Findingnone given

    Pyrolysis has a lower reaction temperature than gasification.

    “When comparing pyrolysis and gasification, the pyrolysis process has a lower reaction temperature than the gasification process.”
    Quote in the paperNot a substantial claim

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

    Findingreasoning

    Some characterised substances are not assigned to any of the categories and are instead categorised as 'others'.

    “Some characterised substances are not assigned to any of the categories and are instead categorised as “others”.”
    Quote in the paperNot a substantial claim

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

    Findingnone given

    Some researchers also use carbohydrates, esters, ethers, N-containing compounds, and other compounds.

    “Some researchers also use carbohydrates, esters, ethers, N-containing compounds, and other compounds.”
    Quote in the paperNot a substantial claim

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

    Findingnone given

    The most common classes of studied compounds are hydrocarbons, phenols, carboxylic acids, aldehydes, alcohols, and ketones.

    “The most common classes of studied compounds are hydrocarbons, phenols, carboxylic acids, aldehydes, alcohols, and ketones.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    GC-MS technologies are commonly used for qualitative identification and precise quantitative determination of unknown compounds.

    “It is common to use GCMS technologies for qualitative identification and the precise quantitative determination of unknown compounds [69].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [69] Asteggiano, A., Occhipinti, A., Capuzzo, A., Mecarelli, E., Aigotti, R., and Medana, C. (2021). Quali-Quantitative Characterization of Volatile and Non-Volatile Compounds in Protium heptaphyllum (Aubl.) Marchand Resin by GC-MS Validated Method, GC-FID and HPLC-HRMS2. Molecules, 26. source

      Not checked in the free run.

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

    Premisenone given

    Gasification dissociates carbon-based feedstock at high temperatures from 700 to 1500 °C under sub-stoichiometric conditions.

    “Using gasification process, a carbon-based feedstock is dissociated at high temperatures from 700 to 1500 • C under sub-stoichiometric conditions.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    With DTMS, the sample vapour is created directly within the mass spectrometer's source by the use of a heated filament, allowing for the detection of bigger mass fragments and improved labile compound detection.

    “However, with DTMS, the sample vapour is created directly within the mass spectrometer's source by the use of a heated filament, allowing for the detection of bigger mass fragments and improved labile compound detection [81].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [81] Schilling, M.R., and Learner, T. (2011, January 19–23). Evolved Gas Analysis As a Tool for Characterizing Plastics. Proceedings of the ICOM-CC 16th Trienn. Conference, Lisbon, Spain.

      Not checked in the free run.

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

    Premisecitation

    Heart-cut analysis allows automatic GC-MS analysis of up to eight temperature zones.

    “This technology, which necessitates the use of a Selective Sampler and a Microjet Cryo-Trap, allows for automatic GC-MS analysis of up to eight temperature zones [82].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [82] Akihiko, H., Koichi, I., Ichi, W., and Chuichi, W. Utility of a System Consisting of EGA.PY-3030D and GCMS-QP2010 Ultra, SHIMADZU, C146-E174.

      Not checked in the free run.

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

    Interpretationnone given

    Wet biomass makes a good solvent and reaction environment because its ionic product is greatest at temperatures between 200 and 280°C, in which water may serve as both a base and an acid.

    “Wet biomass makes a good solvent and reaction environment because its ionic product is greatest at temperatures between 200 and 280 • C, in which water may serve as both a base and an acid.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    Hydrothermal liquefaction transforms wet biomass into a liquid fuel.

    “Hydrothermal liquefaction is a thermochemical process that transforms wet biomass into a liquid fuel [56].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [56] Minowa, 1998, Thermochemical liquefaction of Indonesian biomass residues, Biomass Bioenergy source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Hydrothermal carbonisation generates hydrochar as its principal product and aqueous and gas phases as by-products.

    “Hydrothermal carbonisation generates a coal-like substance termed hydro char as its principal product as well as aqueous and gas phases as by-products [62].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [62] Yoganandham, S.T., Sathyamoorthy, G., and Renuka, R.R. (2020). Emerging Extraction Techniques: Hydrothermal Processing, Elsevier Inc. source

      Not checked in the free run.

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

    Interpretationreasoning

    The failure to assign some characterised substances to categories may be due to their dynamic composition or their inability to be identified.

    “This may be due to their dynamic composition or their inability to be identified.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Liquefaction occurs in thermally compressed water at temperatures ranging from 250 to 550 °C and compressed pressures ranging from 5 to 25 MPa.

    “Liquefaction occurs in thermally compressed water at temperatures ranging from 250 to 550 °C and compressed pressures ranging from 5 to 25 MPa.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [57] Akhtar, 2011, A review on process conditions for optimum bio-oil yield in hydrothermal liquefaction of biomass, Renew. Sustain. Energy Rev. source

      Not checked in the free run.

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

    Premisereasoning

    The combination of GC and MS enables both qualitative and quantitative analyses of a sample containing a variety of organic compounds.

    “The combination of the two technologies enables both qualitative and quantitative analyses of a sample containing a variety of organic compounds.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    Torrefaction, pyrolysis, combustion, liquefaction, and gasification are thermochemical conversion processes used to transform lignocellulosic and non-lignocellulosic biomass into biofuels.

    “Torrefaction, pyrolysis, combustion, liquefaction, and gasification are some of the thermochemical conversion processes that are used to transform lignocellulosic and non-lignocellulosic biomass into biofuels [7].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [7] Ong, 2020, A state-of-the-art review on thermochemical conversion of biomass for biofuel production: A TG-FTIR approach, Energy Convers. Manag. source

      Not checked in the free run.

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

    Premisecitation

    During fast pyrolysis, the moisture level of the feedstock should be around 10%.

    “During the fast pyrolysis process, the moisture level of the feedstock should be around 10% [31].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [31] Ivanova, N., Gugleva, V., Dobreva, M., Pehlivanov, I., Stefanov, S., and Andonova, V. (2016). We are IntechOpen, the World’s Leading Publisher of Open Access Books Built by Scientists, for Scientists TOP 1%, IntechOpen.

      Not checked in the free run.

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

    Premisecitation

    GC is used to test blood and other body fluids for medications and toxins after appropriate extraction procedures have been followed.

    “GC is used to test blood and other body fluids for medications and toxins after appropriate extraction procedures have been followed [68].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [68] Shellie, 2013, Gas Chromatography, Encycl. Forensic Sci. Second Ed.

      Not checked in the free run.

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

    Premisecitation

    The ultimate distribution of the gas can influence the design and procurement of gasification and gas upgrading systems and the demands and challenges of gas analysis in the measurement facility.

    “The ultimate distribution of the gas can influence not only the design and procurement of the most appropriate gasification and gas upgrading systems, but it will also influence the demands and challenges of gas analysis in the measurement facility [65].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [65] Bonilla, S.H., Silva, H.R.O., da Silva, M.T., Gonçalves, R.F., and Sacomano, J.B. (2018). Industry 4.0 and sustainability implications: A scenario-based analysis of the impacts and challenges. Sustainability, 10. source

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

    Premisecitation

    At high temperatures, other species such as CO and NO are present in considerable amounts in combustion products.

    “At high temperatures, other species such as CO and NO are present in considerable amounts in combustion products [45].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [45] Caretto, L. (2010). Introduction to Combustion Today′s Class, Spring.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The use of alkaline catalysts reduces the deposition of char while increasing the yield and strength of the oil.

    “The use of alkaline catalysts reduces the deposition of char while increasing the yield and strength of the oil [58].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [58] Zhou, Y., and Hu, C. (2020). Catalytic thermochemical conversion of algae and upgrading of algal oil for the production of high-grade liquid fuel: A review. Catalysts, 10. source

      Not checked in the free run.

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

    Interpretationnone given

    Compared to other thermochemical processes, liquefaction requires lower temperatures, allowing it to save more fuel, generate fewer pollutants, and be considerably less expensive.

    “Compared to other thermochemical processes, liquefaction requires lower temperatures, allowing it to save more fuel, generate fewer pollutants, and be considerably less expensive.”
    Quote in the paperNot a substantial claim

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

    Interpretationcitation

    The application of GC×GC with a time-of-flight mass spectrometer gives a decent option when analysing mixtures of pure samples.

    “The computer program used to manage the data is available, but the application of GC × GC with a time-of-flight mass spectrometer gives a decent option when analysing mixtures of pure samples [78].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [78] Kandiyoti, R., Herod, A.A., and Bartle, K.D. (2006). Analytical Techniques for Low Mass Materials: Method Development. Solid Fuels Heavy Hydrocarb. Liq., 217–260. source

      Not checked in the free run.

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

    Premisecitation

    In gasification, biomass is heated to temperatures exceeding 700 °C to produce syngas, which can be converted to liquid transportation fuels.

    “In gasification, biomass is heated to high temperatures exceeding 700 • C to produce syngas, which can be converted to liquid transportation fuels [19].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [19] Phillips, 2016, The use of conservation biomass feedstocks as potential bioenergy resources in the United Kingdom, Bioresour. Technol. source

      Not checked in the free run.

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

    Premisecitation

    TGA-IST16-GC-MS was designed to determine the comonomer form and quality in a sequence of linear low-density polyethylene (LLDPE).

    “For example, TGA-IST16-GC-MS was designed to determine the comonomer form and quality in a sequence of liner low-density polyethylene (LLDPE).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [76] Boyron, 2019, An Advanced Technique for Linear Low-Density Polyethylene Composition Determination: TGA–IST16–GC–MS Coupling, Macromol. Chem. Phys. source

      Not checked in the free run.

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

    Premisenone given

    Torrefaction is characterised by partly regulated and isothermal pyrolysis of biomass at temperatures ranging from 200 to 300 °C.

    “Torrefaction is characterised by the partly regulated and isothermal pyrolysis of biomass at temperatures ranging from 200 to 300 • C.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The HTC process is predominantly exothermal, with an enthalpy change of the order of 1 MJ per 1 kg of dry biomass material.

    “The process is predominantly exothermal, according to the literature on HTC, with an enthalpy change of the order of 1 MJ per 1 kg of dry biomass material [135].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [135] Pecchi, 2020, Enthalpy change during hydrothermal carbonization of biomass: A critical review, J. Therm. Anal. Calorim. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In biopolymer films, TGA is a valuable instrument for testing the incorporation of nanoparticles and active compounds into biopolymer films or membranes by measuring the rise or decrease in thermal degradation peaks as well as determining the quickest or delayed thermal degradation.

    “In biopolymer films, TGA is a valuable instrument for testing the incorporation of nanoparticles and active compounds into biopolymer films or membranes by measuring the rise or decrease in thermal degradation peaks as well as determining the quickest or delayed thermal degradation [104].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [104] Tomoda, B.T., Yassue-Cordeiro, P.H., Ernesto, J.V., Lopes, P.S., Péres, L.O., da Silva, C.F., and de Moraes, M.A. (2020). Characterization of biopolymer membranes and films: Physicochemical, mechanical, barrier, and biological properties. Biopolym. Membr. Film., 67–95. source

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

    Premisecitation

    TGA's heat-up intensity ranges from 0.1 to 200 °C/min.

    “TGA's heat-up intensity ranges from 0.1 to 200 • C/min [105].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [105] Ebnesajjad, S. (2014). Surface and Material Characterization Techniques, William Andrew Publishing. source

      Not checked in the free run.

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

    Interpretationnone given

    DSC can be used to measure transitions such as glass transition, melting, and crystallisation.

    “DSC can be used to measure transitions such as glass transition, melting, and crystallisation.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    When endothermic or exothermic phenomena, such as transition and reaction, occur in the sample, these phenomena are compensated by the heat sink.

    “When endothermic or exothermic phenomena, such as transition and reaction, occur in the sample, these phenomena are compensated by the heat sink [133].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [133] Stark, W., and Bohmeyer, W. (2013). Non-Destructive Evaluation (NDE) of Composites: Using Ultrasound to Monitor the Curing of Composites, Woodhead Publishing. source

      Not checked in the free run.

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

    Interpretationreasoning

    Although sublimation, evaporation, and thermal decomposition can all be monitored by DSC, this method is rarely used for them due to the mass change caused by decomposition and the sensor degradation caused by the decomposed gas.

    “Although sublimation, evaporation, and thermal decomposition can all be monitored, this method is rarely used due to the mass change caused by decomposition and the sensor degradation caused by the decomposed gas.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    TGA-FTIR reliably records the mass loss when a sample is heated up in the TGA analyser and detects the released molecular species as a result of the associated mass loss by passing the released molecular species through the FTIR instrument's long optical path glass cell.

    “It reliably records the mass loss when a sample is heated up in the TGA analyser and detects the released molecular species as a result of the associated mass loss by passing the released molecular species through the FTIR instrument's long optical path glass cell [107].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [107] Heetderks, B.T., and Wang, X. (2019). Thermogravimetric Analysis—Fourier Transfer Infrared Spectroscopy (TGA—FTIR) Services Thermogravimetric Analysis—Fourier Transfer Infrared Spectroscopy ( TGA—FTIR) Services. EAG Appl. Note, M-039719.

      Not checked in the free run.

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

    Premisecitation

    The second approach for separating the thermal effect of water heating from that of the HTC process is based on the same theoretical foundation as the first, and it produces similar outcomes.

    “The second approach is based on the same theoretical foundation as the first, and it produces similar outcomes [136].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [136] Pecchi, 2020, Thermodynamics of hydrothermal carbonization: Assessment of the heat release profile and process enthalpy change, Fuel Process. Technol. source

      Not checked in the free run.

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

    Interpretationnone given

    The rapid advancement of analytical techniques and data processing methods can broaden the spectrum of multivariate analysis applications, which can be useful especially in determining the composition of complex matrices with many different components.

    “Finally, the rapid advancement of analytical techniques and data processing methods can broaden the spectrum of multivariate analysis applications, which can be useful especially in determining the composition of complex matrices with many different components.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    FTIR spectroscopy is based on the association of molecules with electromagnetic radiation in the mid-infrared spectral range of 4000 to 400 cm-1.

    “FTIR spectroscopy is based on the association of molecules with electromagnetic radiation in the mid-infrared spectral range of 4000 to 400 cm -1 [106].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [106] Schubnell, 2017, Thermogravimetry and gas analysis, Part 1: Basic principles and overview, Mettler Toledo User Com

      Not checked in the free run.

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

    Premisecitation

    Peaks in the ion current signal for a given m/z indicate the presence of molecules in the gas flow that can separate into ions with this mass-to-charge ratio after ionisation.

    “Peaks in the ion current signal for a given m/z indicate the presence of molecules in the gas flow that can separate into ions with this mass-to-charge ratio after ionisation [106].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [106] Schubnell, 2017, Thermogravimetry and gas analysis, Part 1: Basic principles and overview, Mettler Toledo User Com

      Not checked in the free run.

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

    Interpretationnone given

    DSC can be used to measure chemical reactions such as thermal curing heat history, specific heat capacity, and purity analysis.

    “Chemical reactions can also be measured, such as thermal curing heat history, specific heat capacity, and purity analysis.”
    Quote in the paperNot a substantial claim

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

    Interpretationreasoning

    The common use of GC and TGA stems from the technique's high flexibility and ability to screen quickly the composition.

    “It stems from the technique's high flexibility and ability to screen quickly the composition.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    GC × GC may provide more precise knowledge on the contribution on specific chemical compounds.

    “The study revealed that GC × GC may provide more precise knowledge on the contribution on specific chemical compounds.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Using a traditional NiMo/Al2O3 refinery catalyst, hydrogen compound classes increase significantly, while heteroatomic compound classes decrease.

    “Hydrogen compounds classes are increases Using a traditional NiMo/Al 2 O 3 refinery catalyst, significantly, while heteroatomic compounds classes decrease.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [90] Rathsack, 2019, Analysis of hydrogenation products of biocrude obtained from hydrothermally liquefied algal biomass by comprehensive gas chromatography mass spectrometry (GC×GC-MS), Fuel source

      Not checked in the free run.

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

    Interpretationreasoning

    TGA-FTIR integrates the power of TGA with the precision of FTIR substance characterisation and outgassing profiling.

    “TGA-FTIR integrates the power of TGA with the precision of FTIR substance characterisation and outgassing profiling.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    DSC is frequently used to determine the polymer breakdown behaviour.

    “DSC is frequently used to determine the polymer breakdown behaviour [132].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [132] Sindhu, R., Binod, P., and Pandey, A. (2015). Microbial Poly-3-Hydroxybutyrate and Related Copolymers, Elsevier B.V. source

      Not checked in the free run.

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  • The authors state this as an assumption.

    For well-maintained lean combustion systems, the assumption of full combustion is usually reasonable.

    “For well-maintained lean combustion systems, the assumption of full combustion, in which all of the fuel carbon reacts to carbon dioxide, all the fuel hydrogen responds to H 2 O, all of the fuel sulphur reacts to SO 2 , and all of the fuel nitrogen reacts to N 2 , is usually reasonable.”

  • The paper relies on this without support.

    The amount of hydrochar produced depends on the process parameters and feedstock used.

    “The amount of hydro char produced depends on the process parameters and feedstock used.”

  • The paper relies on this without support.

    Decarboxylation, dehydration, and polymerisation are the major mechanisms involved in hydrothermal carbonisation.

    “Decarboxylation, dehydration, and polymerisation are the major mechanisms involved in this process.”

  • The paper relies on this without support.

    The dielectric constant of water decreases at high temperatures, making it behave more as a nonpolar solvent.

    “Furthermore, the dielectric constant of water decreases at high temperatures, making it behave more as a nonpolar solvent.”

  • The paper relies on this without support.

    The most common thermochemical reactions are combustion, torrefaction, pyrolysis, liquefaction, and gasification.

    “The most common thermochemical reactions are combustion, torrefaction, pyrolysis, liquefaction, and gasification.”

  • The paper relies on this without support.

    Gas chromatography is the most popular method for analysing fire residues.

    “Gas chromatography (GC) is the most popular method for analysing fire residues.”

  • The paper relies on this without support.

    Py-GC-MS is one of the most widely used methods for analysing biomass activity during the flash pyrolysis process.

    “Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) is one of the most widely used methods for analysing biomass activity during the flash pyrolysis process.”

  • The paper relies on this without support.

    TGA-GC-MS is now the tool of preference for qualitative and quantitative evolved gas analysis.

    “For qualitative and quantitative evolved gas analysis (TGA), thermogravimetric analysis along with gas chromatography and mass spectrometry (TGA-GC-MS) is now the tool of preference.”

  • The paper relies on this without support.

    TGA is a fast and reliable tool.

    “TGA is a fast and reliable tool.”

  • The paper relies on this without support.

    The typical water/biomass ratio for biomass HTC ranges from 5 to 20.

    “Since the typical water/biomass ratio for biomass HTC ranges from 5 to 20, the separation of the thermal effect associated with the heating of water from that associated with the process is the main problem when dealing with the DSC measurements for the assessment of the enthalpy change of the HTC process.”
10 of 10

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?

  • The products from thermochemical processes consist of a solid fraction (biochar), a liquid fraction (bio-oil or py-oil), and a gaseous fraction (syngas).

    “The products from these processes consist of a solid fraction (biochar), a liquid fraction (bio-oil or py-oil), and a gaseous fraction (syngas) [134,135].”

    From Biofuels, E-Fuels, and Waste-Derived Fuels: Advances, Challenges, and Future Directions (2025) · cites this paper as [135]

    Section 2.2 (Pyrolysis) says pyrolysed feedstocks yield a liquid, syngas, and a solid, and identifies the liquid as bio-oil and the solid as biochar. But the claim extends that three-fraction description to thermochemical processes generally; the comparison table lists other processes, including combustion, with different purposes and products. (LLM, conf=0.87)

    Experimental — accuracy not yet measured

  • Production of gaseous biofuels from biowaste materials primarily employs thermochemical conversion processes such as gasification, pyrolysis, and hydrothermal liquefaction.

    “The production of gaseous biofuels from biowaste materials primarily employs thermochemical conversion processes such as gasification, pyrolysis, and hydrothermal liquefaction [135].”

    From Biofuels, E-Fuels, and Waste-Derived Fuels: Advances, Challenges, and Future Directions (2025) · cites this paper as [135]

    Sections 2.1 (Gasification) and 2.2 (Pyrolysis) describe producing syngas from biomass, supporting those examples. Section 2.5 (Hydrothermal Liquefaction) instead identifies liquid fuel as the main product and gas as a by-product. The Introduction also describes biological methods as widely used for hydrogen production, so the review does not establish that gaseous biofuel production primarily uses the three processes listed. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • The thermochemical pathway utilizes heat to convert biomass into gaseous, liquid, and solid fractions through thermal decomposition.

    “The thermochemical pathway utilizes heat to convert biomass into gaseous, liquid, and solid fractions through thermal decomposition [134,135].”

    From Biofuels, E-Fuels, and Waste-Derived Fuels: Advances, Challenges, and Future Directions (2025) · cites this paper as [135]

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.

  • Beechwood aldehyde-compound count differs from its list

    Minor

    The narrative reports seven types of aldehyde compounds for beechwood, whereas Table 3 lists six.

  • Pyrolysis Arrhenius equation is cited with the wrong number

    Minor

    The pyrolysis passage calls its Arrhenius equation Equation (4), but the displayed equation is numbered (6). Equation (4) appears earlier as a gasification energy-efficiency expression.

  • Pyrolysis conversion equation is cited with the wrong number

    Minor

    The passage directs readers to Equation (5) for the conversion degree a, but the displayed conversion equation is numbered (7).

  • Beechwood ketone count differs from its list

    Minor

    The narrative reports 10 types of ketones for beechwood, whereas Table 3 lists 11 entries under ketones.

4 of 4

Cites

Flagged first, then by citations

Research works printed but not linked: 4

  1. Shellie, 2013, Gas Chromatography, Encycl. Forensic Sci. Second Ed., 1, 579
  2. (2017). Modern Practice of Gas Chromatography, International Journal of Agriculture Innovation and Research.
  3. Schilling, M.R., and Learner, T. (2011, January 19–23). Evolved Gas Analysis As a Tool for Characterizing Plastics. Proceedings of the ICOM-CC 16th Trienn. Conference, Lisbon, Spain.
  4. Schubnell, 2017, Thermogravimetry and gas analysis, Part 1: Basic principles and overview, Mettler Toledo User Com, 45, 1

Cited by

Sorted by citations

Related

Authors
Teh, J. S., Teoh, Y. H., How, H. G., & Sher, F.
Affiliations
  • Universiti Sains Malaysia (MY)
  • UOW Malaysia KDU Penang University College (MY)
  • Nottingham Trent University (GB)
Corresponding author
  • Teoh, Yew Heng
  • Sher, Farooq
ORCID
Venue
Processes
Publisher
MDPI AG
Published
2021-09-08
Volume
9
Issue
9
Pages
1610
ISSN
2227-9717 (ISSN-L)
DOI
10.3390/pr9091610
OpenAlex
W3196360906
Semantic Scholar
8ef25239eda8500a82c7c1f6aaa04a5e52d6619f
Cited by
68
References
131
Citations by year
2026: 12 · 2025: 17 · 2024: 15 · 2023: 13 · 2022: 10 · 2021: 1
FWCI
2.96
Type
journal article
Language
en
Open access
Licence
Locations
  • Processes (publishedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Nottingham Trent University's Institutional Repository (Nottingham Trent Repository) (submittedVersion)
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › Thermochemical Biomass Conversion Processes
  • Physical Sciences › Materials Science › Materials Chemistry › Thermal and Kinetic Analysis
  • Physical Sciences › Engineering › Biomedical Engineering › Biofuel production and bioconversion
Keywords
biomass feedstock, thermal analysis, thermogravimetric analysis, gas chromatography, pyrolysis, torrefaction, gasification, hydrothermal liquefaction, combustion, co-pyrolysis, co-gasification, thermochemical conversion, biomass composition, bioenergy

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 2026-10-10.

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

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.

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