Cellulosic materials, pyrolysis

Fred s major contributions were in the area of combustion and pyrolysis of cellulosic materials. At Montana, he developed a research program for unravelling the complex, consecutive and concurrent reactions involved in... 

Shafizadeh, F. (1968). Pyrolysis and combustion of cellulose materials. Adv. Carbohydr. Chem. 23 419, 474. 

M. Miura et al.. Microwave pyrolysis of cellulosic materials for the production of anhydrosugars. Journal of Wood Science, 47, 502-506 (2001). 

Although there has been a rapid decline in commercial destructive distillation of wood, manufacture of activated carbon by the pyrolysis of cellulosic materials still constitutes a major commercial operation. Finally, the possibility of developing new processes for production of special chemicals by the pyrolysis of cellulose, or the adaptation of the old process to the economy of developing nations blessed with rich forest resources, cannot be overlooked. Controlled pyrolysis of cellulose and cellulosic materials to provide a totally impermeable carbon and other industrial products is an example of the former possibilities. 

The rate and kinetics of the thermal degradation of cellulosic materials have been investigated under a variety of conditions. However, these studies often relate to one of the physical effects produced by the overall process of heating or pyrolysis, instead of the kinetics of the individual chemical reactions involved. Consequently, the results are controversial and confusing. The variation of the results obtained under different conditions provides a vivid indication of the complexity of the reactions involved and the limited value of the overall kinetic data. 

Application of difiFerential thermal analysis and thermogravimetric analysis techniques to the pyrolysis of cellulose is obviously complicated by the complexity of the reactions involved, and the corrections and simplifying assumptions that are required in calculating the kinetic parameters. Consequently, these methods provide general information, instead of accurate identification and definition of the individual reactions (and their kinetics), which are traditionally conducted under isothermal conditions. The data obtained by dynamic methods are, however, useful for comparing the efiFects of various conditions or treatments on the pyrolysis of cellulose. In this respect, the application of thermal analysis for investigating the effect of salts (and flame retardants in general) on the combustion of cellulosic materials is of special interest and will be discussed later (see p. 467). 

The former variables affect the deposition of heat in the solid fuel and its transient temperature-profile, as well as the diffusion of the volatile pyrolysis products and their distribution and mixing with the surrounding atmosphere. The latter factors influence the nature and sequence of the primary and secondary reactions involved, the composition of the flammable volatiles, and, ultimately, the kinetics of the combustion. Consequently, basic study of the combustion of cellulosic materials or fire research has been channeled in these two directions. 

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