PYROLYSIS OF COTTONWOOD 



One of the goals of this study was to investigate the pyrolysis of whole wood and 

 its major components with and without the presence of additives. In order to carry 

 this out, cottonwood was studied by TGA, DTA, and pyrolysis GLC, using the methods 

 previously described. The thermal analysis of untreated cottonwood was presented in 

 a previous section. The pyrolysis products from untreated cottonwood, cottonwood 

 treated with 5 percent ZnCl2, or 5 percent NaOH, as well as the TGA and DTA of treated 

 wood, will be presented in this section. Since lignin complicates the study of wood, 

 some work with this component was necessary. The TGA of lignin has been previously 

 presented and a limited amount of pyrolysis GLC data is discussed here. As previously 

 noted, the thermogram of cottonwood is quite complex. Pyrolysis of each component 

 can be identified by its characteristic thermal behavior and the thermogram of the 

 whole wood is a composite of the thermal behavior of all of the components. 



Treatment of cottonwood with 5 percent ZnCl2, which can be observed by DTA 

 (fig. 16), shows the effect of this additive on each component. The xylan endotherm 

 beginning at 175° C. and the cellulose endotherm beginning at 240° C. were both present. 

 However, the net endotherm from cellulose was greatly reduced by the exotherm of xylan 

 from 250° to 300° C. The TGA also appears to be a composite of the pyrolysis behavior 

 of the components. Table 7 shows computations which account for the char from TGA of 

 wood and its components, assuming no effect of ZnCl2 or NaOH on the amount of lignin char. 



Temperature (°C.) Temperature (°C.) 



Figure 16. — (Left) Thermogram of cottonwood treated with 5 percent zinc chloride. 

 (Right) Thermogram of cottonwood treated with 5 percent sodium hydroxide. 



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