Role of Hydrochar Properties on the Porosity of Hydrochar-based Porous Carbon for Their Sustainable Application

In recent years, chemical activation of hydrochar (a solid material from hydrothermal carbonization (HTC) of lignocellulosic biomass) has been shown to be effective in producing advanced porous materials. However, the linkage between the properties of hydrochar and the porosity of hydrochar-based porous carbon (a material from the chemical activation of hydrochar) has not yet been clearly explored. In the present study, the results indicated that the properties of hydrochar (including stability, thermal recalcitrance, aromaticity and polarity) were greatly affected by the HTC process (peak temperature and retention time). Accordingly, the porosities of hydrochar-based porous carbon (including surface area and pore volume) were determined by the properties of hydrochar. For instance, positive correlations were founded between porosities of porous carbon materials and element compositions (H/C, O/C, and (O+N)/C) of hydrochar materials. Moreover, negative correlations were observed between the porosities of porous carbon materials and thermal recalcitrance of hydrochar materials. In general, a porous carbon with high porosity was produced from a hydrochar with HTC process of low peak temperature and retention time. Undoubtedly, hydrochar-based porous carbons retain features characteristic of its parent material.