Abstract
Three types of hydrocarbon (potato starch, glucose and cellulose) were carbonized by superheated steam treatment, and their carbonization characteristics and reaction kinetics were investigated. To minimize the influence of the rate of heat transfer into the materials, fine powdery samples were used. Carbonization temperatures ranged from 498 K (225°C) to 548 K (275°C) . Potato starch melted and swelled at around 225°C, and carbonization proceeded with foaming of the sample. Glucose melted and swelled within a few minutes after treatment, and carbonization proceeded in a foamy state. Cellulose was carbonized without melting, and a powdery charcoal product was obtained. The carbonization rates of the three samples obeyed a first order rate equation. The activation energies for carbonization, evaluated from the rate constants, were in the range 133-167 kJ/mol, which is almost the same as the activation energies for thermal decomposition of starch and cellulose under nitrogen gas.
