Kinetic Analysis of Pulping of Rice Straw with p-Toluene Sulfonic Acid

The kinetics of pulping of rice straw was studied with p-toluenesulfonic acid (p-TsOH). Pulping with 50% p-TsOH aqueous solution was performed at 70-100 degrees C for 0-360 min. The results showed that the delignification reaction could be divided into two phases: the bulk delignification phase and the supplementary delignification phase. Lignin dissolution was the main process in the bulk delignification stage, accompanied by the degradation of a small amount of carbohydrates. In the supplementary delignification stage, the delignification rate was low and carbohydrate degradation was severe. The degradation of carbohydrates is mainly based on the dissolution of hemicellulose. A combined delignification factor (CDF) and a combined hydrolysis factor (CHF) were used to compare severity-based kinetic analyses. The results showed that the degradation process for lignin and hemicellulose can be well-fitted using CDF and CHF models. The fitted results show that the activation energy of the hemicellulose loss reaction and delignification reaction was 68.21 and 46.05 kJ/mol, respectively. Therefore, the use of p-TsOH for pulping is a technology with very broad application prospects.