Supercritical water processes: Future prospects

Cocero, Marı́a José

doi:10.1016/j.supflu.2017.11.018

Cited by 50 publications

(9 citation statements)

References 62 publications

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“…Biopolymer with complex amorphous monomer is lignin which binds the cell fibres together. As this complex monomer is thermally stable, lignin can be decomposed only at high temperatures [68]. Despite the difference in composition the interest in these polysaccharides or polymers increases due to its higher heating value.…”

Section: Woody Biomassmentioning

confidence: 99%

Lignocellulosic and algal biomass for bio-crude production using hydrothermal liquefaction: Conversion techniques, mechanism and process conditions: A review

Venkatachalam¹,

Ravichandran²,

Sengottian³

2021

Environmental Engineering Research

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Thermochemical conversion is an effective process in production of biocrude. It mainly includes techniques such as torrefaction, liquefaction, gasification and pyrolysis in which Hydrothermal Liquefaction (HTL) has the potential to produce significant energy resource. Algae, one of the third-generation feedstocks is placed in the top order for production of bio-oil compared to the first and second-generation feedstock, as the algae can get multiplied in shorter time with the uptake of greenhouse gases. In HTL, the subcritical water helps the biomass to undergo thermal depolymerisation and produce various chemicals such as nitrogenates, alkanes, phenolics, esters, etc. The produced “biocrude” or “bio-oil” may be further upgraded into value-added chemicals and fuels. In addition, the bio-gas and bio-char are also synthesized as by-products. This review provides an overview of different routes available for thermochemical conversion of biomass. It also provides an insight on the operating parameters such as temperature, pressure, dosage of catalyst and solvent for lignocellulosic and algal biomass under HTL environment. In extent, the article covers the conversion mechanism for these two feedstocks and also the effects of the operating parameters on the yield of biocrude are studied in detail.

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Section: Woody Biomassmentioning

confidence: 99%

Lignocellulosic and algal biomass for bio-crude production using hydrothermal liquefaction: Conversion techniques, mechanism and process conditions: A review

Venkatachalam¹,

Ravichandran²,

Sengottian³

2021

Environmental Engineering Research

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“…One of the main challenges regarding biomass feedstock management is pumping the highly concentrated and twophase biomass feedstock in supercritical and subcritical conditions. In addition, the feedstock concentration varies during the operation as well as occasionally containing solid particles [129,157,158]. The dry matter content in the biomass feedstock should be within the pumpability limits of high-pressure pumps to avoid clogging problems while optimizing the product yields versus the energy required to heat the feedstock.…”

Section: Pumpability Of the Feedstock Versus Concentrationmentioning

confidence: 99%

Analysis of operational issues in hydrothermal liquefaction and supercritical water gasification processes: a review

Ghavami

Özdenkçi

Salierno

et al. 2021

Biomass Conv. Bioref.

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Biomass is often referred to as a carbon–neutral energy source, and it has a role in reducing fossil fuel depletion. In addition, biomass can be converted efficiently into various forms of biofuels. The biomass conversion processes involve several thermochemical, biochemical, and hydrothermal methods for biomass treatment integration. The most common conversion routes to produce biofuels include pyrolysis and gasification processes. On the other hand, supercritical water gasification (SCWG) and hydrothermal liquefaction (HTL) are best suitable for converting biomass and waste with high moisture content. Despite promising efficiencies, SCWG and HTL processes introduce operational issues as obstacles to the industrialization of these technologies. The issues include process safety aspects due to operation conditions, plugging due to solid deposition, corrosion, pumpability of feedstock, catalyst sintering and deactivation, and high production costs. The methods to address these issues include various reactor configurations to avoid plugging and optimizing process conditions to minimize other issues. However, there are only a few studies investigating the operational issues as the main scope, and reviews are seldomly available in this regard. Therefore, further research is required to address operational problems. This study reviews the main operational problems in SCWG and HTL. The objective of this study is to enhance the industrialization of these processes by investigating the operational issues and the potential solutions, i.e., contributing to the elimination of the obstacles. A comprehensive study on the operational issues provides a holistic overview of the biomass conversion technologies and biorefinery concepts to promote the industrialization of SCWG and HTL.

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“…The high-temperature, high-pressure water reaction conditions (>100 °C, >1 atm) known as hydrothermal have received increasing attention because of the ability to finetune the water physicochemical properties by pressure and temperature adjustments (Byrappa & Yoshimura, 2012;Carr et al, 2011;Cocero, 2018;Savage, 2009;). Around the critical conditions (T c 374 °C, P c :22.1 MPa, ρ c :320 kg.m -3 ), water characteristics such as diffusivity, viscosity, dielectric constant, and solvation properties change dramatically with small changes in pressure due to large compressibility of critical fluids.…”

Section: Introductionmentioning

confidence: 99%

Effect of Process Conditions on Catalytic Hydrothermal Oxidation of p-Xylene to Terephthalic Acid

Yeop¹,

Ismail²,

Daud³

2022

JST

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This study investigates the influence of hydrothermal process conditions on the yield of terephthalic acid (TPA). Deionised water was employed as a green reaction medium substitute for acetic acid solvent widely used in the Amoco oxidation process for TPA production. Utilising the unique properties of water at elevated temperature and pressure, TPA was synthesised from p-xylene under subcritical (250 °C, 300 °C and 350 °C) and supercritical (400 °C) water conditions in a 10 mL micro-bomb batch reactor. Process conditions, including hydrogen peroxide (H2O2) oxidant concentrations, manganese bromide (MnBr2) catalyst and water loadings, were varied at a fixed reaction time of 60 minutes. The p-xylene conversion and TPA yield were determined using high-performance liquid chromatography (HPLC). In addition, the presence of chemical functional groups and chemical compositions of the reaction products were examined using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometer (GC-MS), respectively. It was found that an optimum TPA yield of 94.56% was observed at 350°C with hydrogen peroxide, deionised water and manganese bromide catalyst set at 1.5 mL, 2.5 mL, and 2 mL, respectively. Other major reaction products identified were p-tolualdehyde and 1,4-hydroxymethyl benzaldehyde.

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Supercritical water processes: Future prospects

Cited by 50 publications

References 62 publications

Lignocellulosic and algal biomass for bio-crude production using hydrothermal liquefaction: Conversion techniques, mechanism and process conditions: A review

Lignocellulosic and algal biomass for bio-crude production using hydrothermal liquefaction: Conversion techniques, mechanism and process conditions: A review

Analysis of operational issues in hydrothermal liquefaction and supercritical water gasification processes: a review

Effect of Process Conditions on Catalytic Hydrothermal Oxidation of p-Xylene to Terephthalic Acid

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