The effect of aqueous phase recirculation on hydrothermal liquefaction/carbonization of biomass: A review

Leng, Songqi; Leng, Lijian; Chen, Linlin; Chen, Jiefeng; Chen, Jie; Zhou, Wenguang

doi:10.1016/j.biortech.2020.124081

Cited by 73 publications

(41 citation statements)

References 111 publications

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“…As mentioned in the previous sections, the changes in the chemical composition of hydrochars after recirculation steps are primarily due to the catalytic role of organic acids concentrating in recycled PW. The increasing carbon content and decreasing oxygen content demonstrate that deoxygenation is promoted by PW recirculation [43]. Sugars derived from the hydrolysis of hemicellulose and cellulose are dehydrated into intermediates such as HMF which are further dehydrated and decarboxylated, producing H 2 O and CO 2 [78].…”

Section: Effect On Chemical Compositionmentioning

confidence: 99%

“…The effect of residence time on the HTC PW recirculation process when compared to conventional HTC is similar. At longer residence times, the organics and less stable compounds in solution react, increasing solid yields [43]. Stemann et al [74] and Wang et al [46] found that the HMF concentration decreased after recirculation steps with residence times of 4 h and 2 h respectively, to form new solid phase structures, while Kambo et al [71] reported a HMF content stable after 10 recirculation steps and a reaction time of 5 min; thus, very short residence times seem to be insufficient to allow an increase of HMF concentration capable to induce its conversion into hydrochar.…”

Section: Influence Of Operating Conditions On Pw Recirculationmentioning

confidence: 99%

“…The amount of water in HTC should be such that it ensures the occurrence of hydrothermal reactions for the whole biomass sample as well as sufficient heat and mass transfer [91]. Experiments were usually carried out with a biomass to water ratio of 1:4 to 1:10 [43]. When high biomass to water ratios are used, large concentrations of reactive by-products will be present in the liquid medium; therefore, liquid to solid pathways could be likely to start earlier, leading to an increase in hydrochar yield after few recirculation steps [92][93][94].…”

Section: Challenges and Research Opportunitiesmentioning

confidence: 99%

“…The challenges in understanding the influence of PW recirculation during HTC are also related to the lack of studies using advanced analytical methods, such as HPLC or more sophisticated techniques. Analytical methods such as Fourier transform ion-cyclotron resonance mass spectrometer could help to shed a better light on PW compositions and its variation during recirculation steps [43,97]. Hydrochars obtained after PW recycling should also be characterized in terms of surface chemistry and morphology [66].…”

Section: Challenges and Research Opportunitiesmentioning

confidence: 99%

“…Reuse and valorization of post-processing water represent one of the most relevant challenges to make the HTC process more economically viable and environmentally friendly. The recirculation of PW as reaction medium of the hydrothermal process is a promising approach, which, on the one hand, could minimize the hydrothermal wastewater discharge and, on the other hand, could increase the yield of solid biofuel and thus, carbon recovery [43].…”

Section: Introductionmentioning

confidence: 99%

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Process Water Recirculation during Hydrothermal Carbonization of Waste Biomass: Current Knowledge and Challenges

2021

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Hydrothermal carbonization (HTC) is considered as an efficient and constantly expanding eco-friendly methodology for thermochemical processing of high moisture waste biomass into solid biofuels and valuable carbonaceous materials. However, during HTC, a considerable amount of organics, initially present in the feedstock, are found in the process water (PW). PW recirculation is attracting an increasing interest in the hydrothermal process field as it offers the potential to increase the carbon recovery yield while increasing hydrochar energy density. PW recirculation can be considered as a viable method for the valorization and reuse of the HTC aqueous phase, both by reducing the amount of additional water used for the process and maximizing energy recovery from the HTC liquid residual fraction. In this work, the effects of PW recirculation, for different starting waste biomasses, on the properties of hydrochars and liquid phase products are reviewed. The mechanism of production and evolution of hydrochar during recirculation steps are discussed, highlighting the possible pathways which could enhance energy and carbon recovery. Challenges of PW recirculation are presented and research opportunities proposed, showing how PW recirculation could increase the economic viability of the process while contributing in mitigating environmental impacts.

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Section: Effect On Chemical Compositionmentioning

confidence: 99%

Section: Influence Of Operating Conditions On Pw Recirculationmentioning

confidence: 99%

Section: Challenges and Research Opportunitiesmentioning

confidence: 99%

Section: Challenges and Research Opportunitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Process Water Recirculation during Hydrothermal Carbonization of Waste Biomass: Current Knowledge and Challenges

2021

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Interfacial Assembly of Nanowire Arrays toward Carbonaceous Mesoporous Nanorods and Superstructures

Xie

Liu

Bao

et al. 2021

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Synthesis of anisotropic carbonaceous nano‐ and micro‐materials with well‐ordered mesoporous structures has attracted increasing attention for a broad scope of applications. Although hard‐templating method has been widely employed, overcoming the viscous forces to prepare anisotropic mesoporous materials is particularly challenging via the universal soft‐templating method, especially from sustainable biomass as a carbon resource. Herein, the synthesis of biomass‐derived nanowire‐arrays based mesoporous nanorods and teeth‐like superstructures is reported, through a simple and straightforward polyelectrolyte assisted soft‐templating hydrothermal carbonization (HTC) approach. A surface energy induced interfacial assembly mechanism with the synergetic interactions between micelles, nanowire, nanorods, and polyelectrolyte is proposed. The polyelectrolyte acts not only as a stabilizer to decrease the surface energy of cylindrical micelles, nanowires and nanorods, but also as a structure‐directing agent to regulate the oriented attachment and anisotropic assembly of micelles, nanowires, and nanorods. After a calcination treatment, the carbon nanorod and teeth‐like superstructure are successfully coupled with Ru to directly produce supported catalysts for the hydrogen evolution reaction, exhibiting much better performance than the isotropic nanospheres based catalyst. This HTC approach will open up new avenues for the synthesis of anisotropic materials with various morphologies and dimensions, expanding the palette of materials selection for many applications.

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Co‐Hydrothermal Carbonization of Cotton Stalks and MnO₂ for Direct Solar Steam Generation with High Efficiency

et al. 2021

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Biomass‐based photothermal materials for solar steam power generation have been a recent research hotspot. However, despite the many research advances that have been made, many challenges remain. For example, high temperature carbonization leads to the loss of hydrophilicity, the surface coating is easy to peel off, hydrothermal carbonization (HTC) does not guarantee the photothermal performance, and hydrothermal carbonization fluid (HTC‐F) is difficult to handle. Herein, a new material (H‐CS/MnO2) is prepared by co‐hydrothermal carbonization of cotton stalks (CS) and MnO2, and a stable and effective evaporation system is designed. While both ensure super hydrophilicity, the stable loading of MnO2 leads to an excellent photothermal performance. Experimental results show that H‐CS/MnO2 reaches 93.46% evaporation efficiency and the evaporation rate can reach 2.43 kg m−2 h−1 under 1 sun. Moreover, by means of recycling, not only the treatment of HTC solution is solved, but also the carbon dots are continuously enriched and exhibit certain photothermal effects during the recycling process. In addition, H‐CS/MnO2 exhibited excellent salt resistance and corrosion resistance. The obtained condensate heavy ion concentration removal rate reached more than 99.9%. Therefore, the H‐CS/MnO2 fabricated herein has the possibility of practical application in the future.

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The effect of aqueous phase recirculation on hydrothermal liquefaction/carbonization of biomass: A review

Cited by 73 publications

References 111 publications

Process Water Recirculation during Hydrothermal Carbonization of Waste Biomass: Current Knowledge and Challenges

Process Water Recirculation during Hydrothermal Carbonization of Waste Biomass: Current Knowledge and Challenges

Interfacial Assembly of Nanowire Arrays toward Carbonaceous Mesoporous Nanorods and Superstructures

Co‐Hydrothermal Carbonization of Cotton Stalks and MnO₂ for Direct Solar Steam Generation with High Efficiency

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The effect of aqueous phase recirculation on hydrothermal liquefaction/carbonization of biomass: A review

Cited by 73 publications

References 111 publications

Process Water Recirculation during Hydrothermal Carbonization of Waste Biomass: Current Knowledge and Challenges

Process Water Recirculation during Hydrothermal Carbonization of Waste Biomass: Current Knowledge and Challenges

Interfacial Assembly of Nanowire Arrays toward Carbonaceous Mesoporous Nanorods and Superstructures

Co‐Hydrothermal Carbonization of Cotton Stalks and MnO2 for Direct Solar Steam Generation with High Efficiency

Contact Info

Product

Resources

About

Co‐Hydrothermal Carbonization of Cotton Stalks and MnO₂ for Direct Solar Steam Generation with High Efficiency