Hydrothermal Carbonization of Australian Saltbush

Keiller, Benjamin G.; Eyk, Philip J. van; Lane, Daniel; Muhlack, Richard; Burton, Rachel A.

doi:10.1021/acs.energyfuels.8b03416

Cited by 12 publications

(12 citation statements)

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“…C=O carbonyl groups (1730–1698 cm –1 ) are also reduced with increasing temperature, likely as a result of decarboxylation reactions of the cellulose, leading to the production of formic acid and CO 2 . These reductions, combined with the shrinkage of the 3400 cm –1 peak, indicate a substantial loss of oxygen-containing functional groups, leading to an overall purging of oxygen from the feedstock . The ability to remove oxygen from a given fuel is an important asset of HTC and is partly responsible for boosting the higher-heating value of the hydrochar …”

Section: Resultsmentioning

confidence: 99%

“…The HTC reaction was performed using a stainless steel custom-built reactor with an electronically heated fluidized bed (Techne, model: SBL-2D) as a heat source, according to previously published methods. 9 In brief, a stainless steel reactor tube with an internal volume of 30 mL, equipped with a thermocouple, pressure transducer, safety valve, and a pair of hand-operated ball valves, was filled to 80% maximum capacity with a biomass-water slurry with a 15% solids loading. The reactor was sealed, and gaseous oxygen within the reactor was purged with nitrogen, resulting in a completely nitrogenous reaction atmosphere.…”

Section: Methodsmentioning

confidence: 99%

“…One such feedstock may be native Australian saltbush, a diverse group of saline-tolerant plants within the Atriplex and Enchylaena geni, which range widely across a great variety of different habitats and ecological conditions within Australia. These plants thrive in low-water, high-salinity areas, have numerous synergistic human applications in agriculture and soil remediation, and have proven to be suitable for HTC treatment . However, there are still many unknowns about the process of HTC, especially with regard to the behavior of lignocellulose during the carbonization reaction.…”

Section: Introductionmentioning

confidence: 99%

“…These plants thrive in low-water, high-salinity areas, have numerous synergistic human applications in agriculture and soil remediation, and have proven to be suitable for HTC treatment. 9 However, there are still many unknowns about the process of HTC, especially with regard to the behavior of lignocellulose during the carbonization reaction.…”

Section: Introductionmentioning

confidence: 99%

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Biochemical Compositional Analysis and Kinetic Modeling of Hydrothermal Carbonization of Australian Saltbush

et al. 2019

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Hydrothermal Carbonization (HTC) is the thermochemical conversion of biomass in subcritical water to form an energy-enriched "hydrochar" as a renewable replacement for coal. Lignocellulosic biomass contains a variety of complex, interconnected biopolymers with very different physical and chemical structures, including hemicellulose, cellulose, lignin, and protein. These differing structures lead to different rates of decomposition during the HTC reaction. Where previous studies have attempted to elucidate these various rates through the use of individual, purified model compounds, the complexity of whole biomass makes understanding these reactions in their natural state difficult. This present study offers a first step toward gaining a more thorough knowledge of the HTC reaction by accurately quantifying the degradation of hemicellulose, cellulose, and lignin within whole biomass, and producing a simple kinetic and mechanistic model to describe this degradation. Australian saltbush was subjected to HTC at three temperatures (200, 230, 260 °C), and four residence times (0, 15, 30, 60 min). The resultant hydrochars were assayed for hemicellulose, cellulose, and lignin content, via HPLC, Updegraff assay, and acetyl bromide assay, respectively. The degradation of each component was measured, and the reaction order n and key Arrhenius parameters reaction rate constant k, activation energy E a , and the pre-exponential factor A 0 were calculated. It was found that hemicellulose degraded fastest (n = 1, E a = 61 kJmol −1 ), cellulose the slowest (n = 0.5, E a = 127 kJmol −1 ), and only a portion of lignin reacted (n = 1, E a = 66 kJmol −1 ), the remaining 22% being stable under HTC conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biochemical Compositional Analysis and Kinetic Modeling of Hydrothermal Carbonization of Australian Saltbush

et al. 2019

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“… 19 In recent years, many researchers have carried out hydrothermal carbonization of various biomasses and analyzed the properties of hydrochars. Keiller et al 20 produced and analyzed hydrochars of Australian saltbush, and the results indicated that the hydrochars possessed numerous similarities to fossil coal, such as higher heating values (HHVs), ratios of C/O and H/C, contents of the volatile matter (VM), fixed carbon (FC), and ash. Samaksaman et al 11 investigated the fuel characteristics of the hydrochars from macadamia nut shells and found that the HHV of the solid product ranged from 22 to 27 MJ/kg.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Temperature on the Properties of Hydrochars Obtained by Hydrothermal Carbonization of Waste Camellia oleifera Shells

et al. 2021

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Hydrothermal carbonization (HTC) is a thermochemical conversion technique that can produce renewable solid biofuel by all types of waste. Waste Camellia oleifera shells (WCOSs) can be used to produce hydrochars via HTC. The effect of HTC temperature on the physicochemical properties and combustion behaviors of hydrochars was analyzed by varying from 150 to 300 °C. The mass yield of hydrochars decreased from 72.45% at 150 °C to 41.88% at 300 °C with the increase in temperature, and the higher heating value increased from 19.22 MJ/kg at 150 °C to 29.97 MJ/kg at 300 °C. The H/C and O/C values reduced from 1.30 and 0.66 of HTC150 to 0.77 and 0.27 of HTC300, respectively. Fourier transform infrared spectroscopy analysis indicated that the functional groups of hydrochar have changed because of the dehydration and decarboxylation reaction. The surface structure of hydrochars was rougher, and many pore structures were found at 240–300 °C by scanning electron microscopy analysis. The combustion behaviors of WCOSs and their hydochars are distinct via thermogravimetric analysis, and the stability of hydrochars was strengthened with the increase in HTC temperature.

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Evaluation of the Char Formation During the Hydrothermal Treatment of Wooden Balls

Pfersich,

Arauzo,

Modugno

et al. 2023

Global Challenges

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With wooden balls, a visualization of the hydrothermal carbonization to show the progress of the conversion to char is presented. In the present study, the balls represent the particles of biomass to investigate the differences in conversion outside and inside of biomass particles, during hydrothermal carbonization. A special focus is on hydrochar and pyrochar formation. The wooden balls are treated in subcritical water at 220 °C for holding times between 0 and 960 min. Even after 960 min, hydrolysis of the original biomass is incomplete as cellulose and hemicellulose are linked by lignin, inhibiting the reaction with water. Moreover, two different pathways of char production can be observed. Inside of the wooden ball pyrochar is formed as any water got that deep in, on the surface hydrochar is fixed, originated from the surrounding liquid. On the ground of the HTC reactor, a thin, brittle precipitate of likely hydrochar or humins can be found either from the precipitation of loosely attached compounds on the surface of the biomass or direct precipitation from the liquid.

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Hydrothermal Carbonization of Australian Saltbush

Cited by 12 publications

References 46 publications

Biochemical Compositional Analysis and Kinetic Modeling of Hydrothermal Carbonization of Australian Saltbush

Biochemical Compositional Analysis and Kinetic Modeling of Hydrothermal Carbonization of Australian Saltbush

The Effect of Temperature on the Properties of Hydrochars Obtained by Hydrothermal Carbonization of Waste Camellia oleifera Shells

Evaluation of the Char Formation During the Hydrothermal Treatment of Wooden Balls

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