Bio-based mesopore material production under Hydrothermal Carbonization and its activation

Abstract

The thesis aims to study the production of corncob derived bio-based mesopore material through hydrothermal carbonization and physical activation. The hydrothermal carbonzation using 2 types of ionic salt include calcium propionate (Ca propionate) and sodium chloride (NaCl) dissolve with deionized (DI) water for the vapor pressure lowering of subcritical water while invariant reation temperature. The hydrothermal medium with ratio of Ca propionate and DI water as 1:20, 1:15 and 1:10 w/w represent the molality of 0.33, 0.43 and 0.65 mole/kg respectively. The ratio of NaCl and DI water as 1:20, 1:15 and 1:10 w/w represent the molality of 0.86, 1.14 and 1.71 mole/kg respectively. rights reserved At the 240 °C reaction temperature, the 1.71 mole/kg hydrothermal medium shown the lowest vapor pressure lowering of 12%. The lowest vapor pressure lowering of hydrothermal system included corncob biomass, NaCl and DI water with ratio of 1:1:10 by weight was 7.33%. The remaining hemicellulose relate to the process severity that is colligated the factors of vapor pressure lowering, ionic salt concentration and biomass to water ratio. The increase of severity result in the decrease of hemicellulose in the exponential pattern with the R2=0.8115. The tendency of hydrochar produced with the higher concentration are smaller pore diameter. The hydrochar and mesopore material that activated via CO2 from this study are the mesopore material (2-50 nm). The O/C and H/C molar element ratio of hydrochar were 0.78-0.84 and 1.60-1.88 while 0.90 and 2.00 belong to the O/C and H/C of corncob. The BET surface area of AC-CC:CaPro:DI (1:1:10) mesopore material is the highest with 7.5885 m2 g-1 occupied with the mean pore diameter of 5.2404 nm. The hydrochar shown significantly high ash content of 72-75 %. The yield of hydrochar and activated mesopore material of Ca propionate ionic liquid ,AC-CC:CaPro:DI (1:1:10), were 57.7 and 31.8 % respectively. The capacity of its bio- based mesopore material was 426. 14 kg/year with unit cost of 212.44 Baht/kg that lowest among this study.