Atmospheric kraft pulping in glycerol

Kraft pulping is the predominant technique for producing chemical pulps from wood. It offers low operational costs, versatility, high-quality pulps, and an efficient closed chemical recovery system. However, the process requires significant investment due to the necessity for pressurized environments and the associated costly equipment. This study explores a novel approach by replacing water with glycerol, allowing kraft pulping to occur at atmospheric pressure. However, the higher viscosity of glycerol compared to water partially limits impregnation. This research investigates the impact of temperature, chemical charge, and chip size on this process for both hardwood and softwood sapwood. The results indicate that lignin dissolution is expedited by reducing chip size for both softwood and hardwood. However, decreasing the chemical charge negatively impacts lignin dissolution. Conversely, increasing the temperature accelerates lignin release.