Effects of Bases on the Pyrolysis of Cotton Cellulose

Abstract

Highly purified cotton cellulose, which has been impregnated with alkali metal bases or basic salts to various weight levels (up to 2% for the bases and up to 5% for the basic salts), was examined by differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermogravimetric analysis (TGA). All analyses were carried out under purified dry nitrogen at heating rates up to 40°/min. The enthalpies ΔH of pyrolyses, transition temperatures, and activation energies were estimated, using published methods and equations. The effect of added base, in the temperature ranges associated with cellulosic thermal degradation (> 280°C), resulted in (1) altered thermal pattern and AH of pyrolysis, (2) lowered transition temperature, (3) no change in first- order reaction kinetics (between 20-80% decomposition), (4) decreased energy of activation, (5) decreased release of "tars," and (6) increased residue (char). These observations are interpreted to mean that the base is acting as a cellulose pyrolysis catalyst. The significance of these results is discussed in relation to recent studies of the pyrolysis of cellulose itself.