The roles of formic acid and levulinic acid on the formation and growth of carbonaceous spheres by hydrothermal carbonization

Qi, Yujie; Song, Biying; Qi, Yang

doi:10.1039/c6ra21312j

Cited by 29 publications

(23 citation statements)

References 37 publications

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“…5a, possibly linked with fast degradation of furfural. The carbonaceous spheres resemble those reported in other works, (Guiotoku et al 2009;Qi et al 2016) investigating humin growth from acid hydrolysis of lignocelluloses, confirming earlier discussions. Consequently, the increase in solid yields can be attributed to humin formation and can be controlled to modify the solid residue properties in the future.…”

Section: Residues Characterisation and Their Potential Applicationssupporting

confidence: 90%

“…The overall trends and negative net yields of formic acid of − 0.9 wt % and − 4.9 wt % were recorded at 200 °C, 90 min, 2 M and 180 °C, 150 min and 1.05 M, indicating that formic acid is consumed in a side reaction. Formic acid has been found to be stable under similar conditions with monomeric sugars, suggesting that such consumption is linked to the lignocellulose feedstock (Flannelly et al 2016;Qi et al 2016). Lignin has been observed to decrease formic acid yields during acid hydrolysis (Yoon et al 2014) and could be attributed to the formylation of lignin under microwave heating (Wang et al 2017).…”

Section: Net Formic Acidmentioning

confidence: 96%

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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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Section: Residues Characterisation and Their Potential Applicationssupporting

confidence: 90%

Section: Net Formic Acidmentioning

confidence: 96%

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

et al. 2019

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“…The discussion about the growth mechanisms of carbon spheres is an ongoing debate. Whereas many studies are focused on the formation of the particles without additives [19][20][21][22][23], others make use of different kinds of additives, such as acids, bases, or salts [24][25][26][27], during the synthesis of the particles. There are several examples in which the usage of an additive results in remarkable larger particles [9,[28][29][30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal carbonization of fructose—effect of salts and reactor stirring on the growth and formation of carbon spheres

Jung

Duman

Zimmermann

et al. 2021

Biomass Conv. Bioref.

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Hydrothermal carbonization (HTC) has become a promising technology for the production of hydrochar and carbon spheres. Several studies indicate a strong dependency of the reaction conditions on the sphere diameter. The usage of additives, such as salts, is one possibility to increase the size of the spheres. However, the growth mechanism which leads to larger particles is not fully understood. In this work, kinetic studies of HTC with fructose were performed with different salts as additives. The growth of the particles (the increase in size) has been compared to the formation rates (increase in yield) of hydrochar by using the reaction rate constants from the kinetic model. The results indicate that the acceleration of the growth rate is independent of the formation rate. It is therefore assumed that coagulation, as a growth mechanism, took place. With longer reaction times, the particles reached a stable particle size, independently from the added salts; therefore, it was assumed that the particles underwent some sort of solidification. The state of matter can therefore be described as an intermediate state between liquid and solid, similar to mesophase pitch. Experiments with a stirrer resulted in squashed particles, which supports the model, that the particles exhibit emulsion-like behavior.

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“…Thus, they were able to elaborate a refined molecular structure (Figure 1). This model is also notable for including covalently bonded LevA in the HT molecular structure, [24a] an observation that has been confirmed by later studies [25] . However, the composition of these spherical particles is not homogenous but rather composite‐like incorporating many different structural units such as aliphatic, furans, condensed benzene rings (occasionally) and other functional groups).…”

Section: Introductionmentioning

confidence: 65%

Influence of Reaction Conditions on Hydrothermal Carbonization of Fructose

Modugno

Titirici

2021

ChemSusChem

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Hydrothermal carbonization is a powerful way to convert cellulosic waste into valuable platform chemicals and carbonaceous materials. In this study, to optimize the process, fructose was chosen as the carbon precursor and the influence of reaction time, acid catalysis, feed gas and pressure on the conversion products is evaluated. 5‐hydroxymethylfurfural (HMF) is produced in high amounts in relatively short time. Both strong and weak acids accelerate fructose conversion. Levulinic acid (LevA) formation is faster than that of hydrothermal (HT) carbon in acidic conditions. Strong acid catalysts should be considered to target preferentially LevA production, whereas milder conditions should be preferred for HMF production. Moreover, a slight initial overpressure of the reactor is always beneficial in terms of conversion. FT‐IR and 13C ss‐NMR spectroscopy and SEM showed that HT carbon evolves through time from a furanic‐based structure with alkylic linkers to an increasingly cross‐linked condensed structure. MALDI‐ToF mass spectrometry showed the existence of a series of oligomers in a mass range within 650 Da and 1500 Da formed by condensation of repeating units.

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The roles of formic acid and levulinic acid on the formation and growth of carbonaceous spheres by hydrothermal carbonization

Abstract: The roles of formic acid and levulinic acid on the formation and growth of carbonaceous spheres.

Cited by 29 publications

References 37 publications

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

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

Hydrothermal carbonization of fructose—effect of salts and reactor stirring on the growth and formation of carbon spheres

Influence of Reaction Conditions on Hydrothermal Carbonization of Fructose

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