Heat capacities and enthalpies of formation were determined for the well-characterized samples of cellulose of different origins. The obtained experimental results allowed us to obtain the accurate values of thermodynamic properties for this material. It was demonstrated that the heat capacity and entropy of cellulose samples can be linearly related with their crystallinity index. The equilibria of the processes of cellulose gasification were considered. The adiabatic temperatures of the gasification and energetic characteristics of the products of cellulose thermolysis were evaluated. ' INTRODUCTIONThe use of plant biomass as fuel and raw material for chemical processing is being increased. 1 The effective operation of energy and processing plants using plant biomass is possible if their working conditions are thermodynamically justified. However, very limited information about thermodynamic properties of cellulose and lignin, the major components of the stem part of biomass, is available. In refs 2 to 3 the heat capacity of cellulose fibers was measured in a drop calorimeter. The heat capacity changes near T = 400 K corresponding to the glass transition were observed. Hatakeyama et al. 4 measured heat capacity of cellulose in the temperature range of (330 to 450) K by differential scanning calorimetry (DSC) and found no anomalies below T = 440 K. In refs 5 to 8 the heat capacity of cellulose was determined in adiabatic calorimeters. Karachevtsev and Kozlov 6 measured the heat capacity in a range of temperatures of (80 to 300) K for two samples dried by different methods and found that the results depend on the method of drying. Uryash et al. 8 determined the heat capacity for cotton microcrystalline cellulose in the temperature range (80 to 330) K. In ref 8 the anomalies at 291 K, 343 K, and 403.5 K were observed in the differential thermal analysis (DTA) curve, and the first anomaly was also found in the heat capacity curve. The energies of combustion for various samples of cellulose were also reported in ref 8 though the samples were not characterized by the ash content.In this work the heat capacities in the temperature range of (5 to 370) K and the enthalpies of formation were determined for the samples of cellulose of different origins and degrees of crystallinity. The obtained experimental results allowed us to obtain the reliable values of thermodynamic properties of cellulose required for the calculation of equilibria of the reactions with the participation of this compound, the adiabatic temperatures of the processes of its gasification, and energetic characteristics of the products of cellulose thermolysis.

Heat capacities and enthalpies of formation were determined for two samples of lignin obtained from rape straw by different methods. The obtained experimental results allowed us to obtain the values of thermodynamic properties for this material. The equilibria of the processes of lignin gasification were considered. The adiabatic temperatures of the gasification and energetic characteristics of the products of lignin thermolysis were evaluated.

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