Impact of hydrothermal carbonization conditions on the formation of hydrochars and secondary chars from the organic fraction of municipal solid waste

Lucian, Michela; Volpe, Maurizio; Gao, Lihui; Piro, G.; Goldfarb, Jillian L.

doi:10.1016/j.fuel.2018.06.060

Cited by 230 publications

(119 citation statements)

References 52 publications

(80 reference statements)

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“…It supports the idea that lower temperatures promote hydrolysis reactions, eliciting the release of organic acids, such as acetic acid. Afterwards, these organic acids show further reactions at higher temperatures [53,54]. This supports the formation of other compounds, because hydrolysis is catalyzed by acids.…”

Section: Characteristics Of Liquid Phasesupporting

confidence: 65%

Hydrothermal Carbonization Brewer’s Spent Grains with the Focus on Improving the Degradation of the Feedstock

2018

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Hydrochar is a very interesting product from agricultural and food production residues. Unfortunately, severe conditions for complete conversion of lignocellulosic biomass is necessary, especially compared to the conversion of sugar compounds. The goal of this work is to improve the conversion of internal carbohydrates by application of a two-steps process, by acid addition and slightly higher water content. A set of experiments at different temperatures (180, 200, and 220 • C), reaction times (2 and 4 h), and moisture contents (80% and 90%) was performed to characterize the solid (high heating value (HHV), elemental) and liquid product phase. Afterwards, acid addition for a catalyzed hydrolysis reaction during hydrothermal carbonization (HTC) and a two-steps reaction (180 and 220 • C) were tested. As expected, a higher temperature leads to higher C content of the hydrochar and a higher fixed carbon (FC) content. The same effect was found with the addition of acids at lower temperatures. In the two-steps reaction, a primary hydrolysis step increases the conversion of internal carbohydrates. Higher water content has no significant effect, except for increasing the solubility of ash components.

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Section: Characteristics Of Liquid Phasesupporting

confidence: 65%

Hydrothermal Carbonization Brewer’s Spent Grains with the Focus on Improving the Degradation of the Feedstock

2018

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“…The experimental results relevant to HTC runs performed on OT are summarized in Table 1. Hydrochar yields decreased with temperature and residence time except for residence times higher than 3 h. Tests performed at 180 and 250 • C and 6-8 h of residence time showed an increase in hydrochar yield compared to 3 h residence time, which could be explained by an increased contribution of back-polymerization at longer residence times [17]. The HHV values progressively increased with temperature and residence time (except a slight decrease at 8 h).…”

Section: Hydrothermal Carbonization Of Olive Trimmingsmentioning

confidence: 87%

“…Under these process conditions, water acts similarly to an organic solvent due to the tremendous changes in its polarity and dielectric constant, and as a catalyst for biomass conversion via hydrolysis, dehydration, and decarboxylation reactions [7][8][9][10][11]. The main product of HTC is a carbon-rich solid material referred to as hydrochar, which finds application as high energy bio-fuel [12][13][14][15][16][17][18][19][20][21], as a pre-treated material for anaerobic digestion enhancement [15,22], as a soil amendment [14,23,24], and as an advanced carbonaceous material [25,26]. The high interest in this wet thermochemical technology, due to its high energy efficiency, relatively mild process conditions, and scalability, has also been testified by the study on its application at the industrial level [27,28].…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal Carbonization Kinetics of Lignocellulosic Agro-Wastes: Experimental Data and Modeling

2019

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Olive trimmings (OT) were used as feedstock for an in-depth experimental study on the reaction kinetics controlling hydrothermal carbonization (HTC). OT were hydrothermally carbonized for a residence time τ of up to 8 h at temperatures between 180 and 250 °C to systematically investigate the chemical and energy properties changes of hydrochars during HTC. Additional experiments at 120 and 150 °C at τ = 0 h were carried out to analyze the heat-up transient phase required to reach the HTC set-point temperature. Furthermore, an original HTC reaction kinetics model was developed. The HTC reaction pathway was described through a lumped model, in which biomass is converted into solid (distinguished between primary and secondary char), liquid, and gaseous products. The kinetics model, written in MATLABTM, was used in best fitting routines with HTC experimental data obtained using OT and two other agro-wastes previously tested: grape marc and Opuntia Ficus Indica. The HTC kinetics model effectively predicts carbon distribution among HTC products versus time with the thermal transient phase included; it represents an effective tool for R&D in the HTC field. Importantly, both modeling and experimental data suggest that already during the heat-up phase, biomass greatly carbonizes, in particular at the highest temperature tested of 250 °C.

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“…1 shows, the spherical coal y ash particles are present in considerably higher numbers on the 10 wt% FA sample than the 5 wt% sample. While it is well known in the eld that char pores can become blocked by tar components, 73 the decrease in volatile matter and lack of tar deposits on SEM images suggest that it is not a tar condensation issue, 74 but rather a result of the presence of FA.…”

Section: Physical and Chemical Characteristicsmentioning

confidence: 95%

Heterogeneous biochars from agriculture residues and coal fly ash for the removal of heavy metals from coking wastewater

Gao

Goldfarb

2019

RSC Adv.

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Impact of hydrothermal carbonization conditions on the formation of hydrochars and secondary chars from the organic fraction of municipal solid waste

Cited by 230 publications

References 52 publications

Hydrothermal Carbonization Brewer’s Spent Grains with the Focus on Improving the Degradation of the Feedstock

Hydrothermal Carbonization Brewer’s Spent Grains with the Focus on Improving the Degradation of the Feedstock

Hydrothermal Carbonization Kinetics of Lignocellulosic Agro-Wastes: Experimental Data and Modeling

Heterogeneous biochars from agriculture residues and coal fly ash for the removal of heavy metals from coking wastewater

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