An overview of microwave hydrothermal carbonization and microwave pyrolysis of biomass

Nizamuddin, Sabzoi; Baloch, Humair Ahmed; Siddiqui, M.T.H.; Mubarak, Nabisab Mujawar; Tunio, M. M.; Bhutto, Abdul Waheed; Jatoi, Abdul Sattar; Griffin, Gregory; Madapusi, Srinivasan

doi:10.1007/s11157-018-9476-z

Cited by 92 publications

(25 citation statements)

References 126 publications

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“…55 Hydrochars produced from biomass have several beneficial properties, such as a high energy density, high carbon content, strong mechanical strength, and a non-fibrous structure. 56,57 Therefore, they can be used in multiple potential applications, including amendments, absorbents, capacitors, fuels, catalysts, and filter aiders. [58][59][60][61] Compared to conventional hydrothermal carbonisation, MA-HTC is faster, more controllable and friendly and energy and technologically more efficient.…”

Section: Microwave-assisted Hydrothermal Carbonisation (Ma-htc)mentioning

confidence: 99%

“…The ultimate analysis of hydrochars provides essential insights into not only the characterisation of these solids but also the reaction mechanism of the MA-HTC process. 57 The reactions involved primarily include deoxygenation, dehydration, and decarboxylation, which overall decrease the amounts of hydrogen and oxygen in the hydrochar. 78,81 At the same time, the carbon content of the hydrochar increases due to condensation and aromatisation reactions.…”

Section: Elemental Compositionmentioning

confidence: 99%

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Microwave-assisted hydrothermal treatments for biomass valorisation: a critical review

2021

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Section: Microwave-assisted Hydrothermal Carbonisation (Ma-htc)mentioning

confidence: 99%

Section: Elemental Compositionmentioning

confidence: 99%

Microwave-assisted hydrothermal treatments for biomass valorisation: a critical review

2021

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“…Furthermore a notable excess of gas formation at higher temperatures (200 °C) was observed, that could not be explained by gas expansion alone. Although the amount of gas formed could not be measured accurately, the formation of gas would potentially indicate hydrothermal carbonization (HTC) is taking place (Nizamuddin et al 2018). HTC has been reported under sub-critical conditions for cellulose and lignin at 180-200 °C (Heidari et al 2018).…”

Section: Residual Solids Yieldsmentioning

confidence: 99%

Solid residue and by-product yields from acid-catalysed conversion of poplar wood to levulinic acid

et al. 2019

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This study examines the yields of solid residue and by-product from the microwave-assisted acid hydrolysis of lignocellulosic poplar wood for levulinic acid production. The aim of this study was to optimise levulinic acid production via response surface methodology (RSM) and also investigate the effect of reaction conditions on other products such as furfural, solid residue, formic acid and acetic acid yields. A maximum theoretical levulinic acid yield of 62.1% (21.0 wt %) was predicted when reaction conditions were 188 °C, 126 min and 1.93 M sulphuric acid, with a corresponding solid residue yield of 59.2 wt %. Furfural from the hydrolysis of hemicellulose was found to have significantly degraded at the optimum levulinic acid yield conditions. The investigation of formic acid yields revealed lower formic acid yields than stoichiometrically expected, indicating the organic acid reactions under microwave-assisted hydrolysis of lignocellulose. The solid residue yields were found to increase significantly with increasing reaction time and temperature. The solid residue yields under all conditions exceeded that of levulinic acid and, therefore, should be considered a significant product alongside the high-value compounds. The solid residue was further examined using IR spectra, elemental analysis and XRF for potential applications. The overall results show that poplar wood has great potential to produce renewable chemicals, but also highlight all by-products must be considered during optimization.

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“…They also studied the effect of four process parameters of MIHTC on the hydrochar yield as well observed a significant improvement in the chemical, fuel, structural and thermal properties of hydrochar after the MIHTC process. A comparative review on MIHTC and microwave pyrolysis was published recently [24].…”

Section: Introductionmentioning

confidence: 99%

Microwave Hydrothermal Carbonization of Rice Straw: Optimization of Process Parameters and Upgrading of Chemical, Fuel, Structural and Thermal Properties

et al. 2019

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The process parameters of microwave-induced hydrothermal carbonization (MIHTC) play an important role on the hydrothermal chars (hydrochar) yield. The effect of reaction temperature, reaction time, particle size and biomass to water ratio was optimized for hydrochar yield by modeling using the central composite design (CCD). Further, the rice straw and hydrochar at optimum conditions have been characterized for energy, chemical, structural and thermal properties. The optimum condition for hydrochar synthesis was found to be at a 180 °C reaction temperature, a 20 min reaction time, a 1:15 weight per volume (w/v) biomass to water ratio and a 3 mm particle size, yielding 57.9% of hydrochar. The higher heating value (HHV), carbon content and fixed carbon values increased from 12.3 MJ/kg, 37.19% and 14.37% for rice straw to 17.6 MJ/kg, 48.8% and 35.4% for hydrochar. The porosity, crystallinity and thermal stability of the hydrochar were improved remarkably compared to rice straw after MIHTC. Two characteristic peaks from XRD were observed at 2θ of 15° and 26°, whereas DTG peaks were observed at 50–150 °C and 300–350 °C for both the materials. Based on the results, it can be suggested that the hydrochar could be potentially used for adsorption, carbon sequestration, energy and agriculture applications.

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An overview of microwave hydrothermal carbonization and microwave pyrolysis of biomass

Cited by 92 publications

References 126 publications

Microwave-assisted hydrothermal treatments for biomass valorisation: a critical review

Microwave-assisted hydrothermal treatments for biomass valorisation: a critical review

Solid residue and by-product yields from acid-catalysed conversion of poplar wood to levulinic acid

Microwave Hydrothermal Carbonization of Rice Straw: Optimization of Process Parameters and Upgrading of Chemical, Fuel, Structural and Thermal Properties

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