부산대학교 도서관

• Three surfactants showed different catalytic HTC mechanisms towards pomelo peel. • Surfactants enhanced mass yield by agglomerating organic intermediates. • SP80/citric acid catalyzed hydrochar had superior mass yield of 63.45 % and HHV of 31.302 MJ/kg. • Fuel blends of HC-SP80/coal showed better combustibility and obvious synergistic effects. Hydrothermal carbonization (HTC) of biomass remained promising as a low-cost and eco-friendly technique for solid fuel production. However, the common HTC approaches usually suffered low mass yields due to the dissolution of intermediates into the liquid phase. In this study, different catalyst solutions were prepared using three surfactants (sodium dodecyl benzene sulfonate (SDBS), Span 80 and Tween 80) and citric acid solution with a pH of 3.61 as the reaction medium. Surfactant/citric acid catalyzed HTC was performed under a 3:1 pomelo peel/surfactant mixing ratio and reaction temperature of 220 °C for 6 h. Compared with the citric acid-catalyzed HTC, SP80/citric acid catalyzed hydrochar demonstrated an increased solid yield from 39.04 % to 63.45 %, and enhanced HHV from 24.122 MJ/kg to 31.302 MJ/kg. Meanwhile, Tween 80 increased the hydrochar solid yield and HHV to 50.17 %, and 28.281 MJ/kg, respectively. The co-firing of hydrochars catalyzed by Span 80 and Tween 80 with coal significantly improved its combustibility, and further reduced the activation energy to 15.20–25.49 kJ/mol. Synergistic effects were observed during the co-combustion of surfactant/citric acid catalyzed hydrochar and coal. This work showed that the unique amphiphilic properties of surfactants can help to regulate the composition of products during acid-catalyzed HTC, resulting in better fuel properties and combustion performance. [ABSTRACT FROM AUTHOR]