Kinetics of cellulose pyrolysis after a pressurized heat treatment

A hot pressure treatment (HPT) converts celluloses into an advantageous feedstock for activated carbon preparation. Other ways of utilization may also emerge in the future. In the present paper the pyrolysis kinetics of three HPT cellulose samples were studied by thermogravimetric analysis (TGA) at linear and stepwise temperature programs. A distributed activation energy model was used assuming two partial reactions. Nine experiments on three samples were evaluated simultaneously by the method of least squares. 20 unknown parameters were determined in this way. Good fits were obtained at the linear and stepwise temperature programs alike. The evaluations were also carried out by non-constant preexponential factors that depended on the activation energy. The considerations and evaluation methods of the paper are hoped to help the investigations of other biomass materials, too. The results showed that part of the cellulose remained unconverted and another part only partially converted at the mildest pretreatment conditions of this study. The cellulose was wholly transformed in the pretreatment when either the pressure or the temperature was increased.