Synthesis of cellulose triacetate from softwood dissolving pulp using p-toluenesulfonic acid and its properties

The ester acid method primarily employs sulfuric acid (H2SO4) as a catalyst and is used in the current cellulose triacetate (CTA) industry from cotton linters. However, the problems of acid wastewater and cellulose degradation caused by H2SO4 still need to be solved. In this study, CTA was successfully produced from bleached softwood dissolving pulp (BSDP) utilizing the recyclable solid acid p-toluenesulfonic acid (p-TsOH). CTA prepared using either H2SO4 or p-TsOH with the same degree of substitution (DS) or the same H+ concentration was compared. The results show that p-TsOH-treated CTA demonstrated better performance in terms of the degree of polymerization (DP), dispersion stability, acetylation rate, and thermal stability. The mechanism for polymerization of acetylation catalyzed by p-TsOH was postulated. The results suggest that using p-TsOH can reduce carbohydrate degradation, solve the problem of inorganic acid derivatization, and allow the use of alternative cellulose resources-bleached wood fibers for producing CTA.