Summary
This narrative review synthesises current understanding of hydrothermal carbonization (HTC) as a thermochemical conversion pathway for wet biomass into carbon-rich hydrochars. It details the fundamental reaction mechanisms (hydrolysis, dehydration, decarboxylation, aromatization) and examines how temperature, residence time, solid/liquid ratio, catalysts, and feedstock composition jointly influence hydrochar properties. The authors identify recent technological advances (microwave-assisted HTC, catalytic modifications, post-activation) that enhance hydrochar functionality and position HTC as a versatile method for circular economy applications, whilst acknowledging outstanding challenges in process scale-up, reactor design, and process water management.
Regional applicability
The review is geographically neutral and mechanistically focused, making its insights on HTC process optimisation and hydrochar applications broadly applicable to United Kingdom biomass valorisation and circular economy strategies, particularly for wet agricultural and food-processing residues common in UK farming systems.
Key measures
Hydrochar yield, elemental composition, aromaticity, porosity, energy density, structural properties, carbon densification
Outcomes reported
This review systematically examines the mechanisms governing hydrothermal carbonization (HTC) of wet biomass, identifies key process parameters affecting hydrochar yield and quality, and assesses sustainable valorization pathways for hydrochar in energy, adsorption, catalysis, and soil enhancement applications.
Topic tags
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