Reaction kinetics of a heterogeneous vapor phase reaction between cellulosic materials and maleic anhydride

Heterogeneous vapor phase reaction of cellulose powder and wood meal with maleic anhydride (MA) was carried out at 140 to 180°C under the existence of excessive amount of MA to the sample without catalyst. The reaction product was fractionated depending on the stability of the formed linkages by additional heating and water leaching. The weight percent gain (WPG) after heating was regarded as a measure of net amount of the product, and analyzed by means of reaction kinetics. Concerning the cellulose powder, it was found that only a part of amorphous region of cellulose participates in the reaction, and that the ratio of stable linkages to unstable ones increases at elevated temperature because of low ultimate WPG compared to the theoretical one and its remarkable dependency on temperature, respectively. Meanwhile, another rate equation was applied to the data for wood meal, in which the contributions of cellulose and substances except for cellulose (lignin and hemicellulose) were separately taken into consideration. The results showed that the dependence of ultimate WPG on reaction temperature was not significant for the substances except for cellulose. The apparent activation energy estimated from the rate constant for the substances except for cellulose was about 40 kj/mol, which suggests the diffusion-controlled reaction. The rate constant and ultimate WPG suggested the relatively lower reactivity for cellulose than that for the substances except for cellulose. ©2007 The Society of Materials Science.