Yuanfeng Dong,Hairui Ji,Cuihua Dong,Wenyuan Zhu,Zhu Long,Zhiqiang Pang
High-grade dissolving pulp was prepared from radiata pine by the pre-hydrolysis Kraft process. The effect of the P-factor in the pre-hydrolysis stage on the properties of wood chips was investigated. With an increasing P-factor, hemicellulose was selectively removed from wood chips, and the crystallized index of the pre-hydrolyzed wood chips increased owing to the dissolution of the amorphous phase in the substrates. Further, sugars in hemicellulose could be rapidly hydrolyzed; whereas, their release became slower with a further increase in the P-factor. Comparatively, arabinose and galactose were readily removed during pre-hydrolysis for its accessibility. Additionally, accumulations of furfural and 5-hydroxymethylfurfural (HMF) were detected via acid-catalyzed dehydration of pentose and hexose, respectively. HMF can be further converted into formic and levulinic acid by acid-catalyzed dehydration. After pre-hydrolysis, the chips were subjected to Kraft cooking, and the optimal P-factor (480) for the production of dissolving pulp and the optimal H-factor (1500) in terms of the Kappa number, viscosity, and α-cellulose of the pulp were obtained. Then, the Kraft pulp was bleached using the (OO)D 0 E OP D 1 D 2 sequence, and a final ISO brightness of 91.0% was achieved with negligible loss in α-cellulose. The described technique and parameters are important for the industrial production of high-grade dissolving pulp using radiata pine.
Pure subcritical water autohydrolysis is an economical and green biorefinery method and potentially applicable technology. Elucidating and regulating the energy input effects on the structural dissociation and chemical depolymerization of lignocellulosic biomass will progress the industrialization of pure subcritical water autohydrolysis biorefineries. In this work, a method for determining the degree of tissue dissociation was invented. Combined with the analysis of the microstructure, ultrastructure, chemical composition, and aggregation state, this paper reveals the process and mechanism of the P-factor effect as an energy input measurement on the bio-structural dissociation and chemical depolymerization during naked oat stem autohydrolysis. A method of using the P-factor to regulate the biostructural dissociation and chemical depolymerization was developed. For the first time, a critical point for the autohydrolysis of naked oat stem in pure subcritical water between 170–210 °C was found to be at a P-factor = 233, around which an essential change in biostructural dissociation and chemical depolymerization occurred. The findings indicate that the control of naked oat-stem tissue and cell dissociation, ultrastructure, and chemical depolymerization can be accomplished using the P-factor as an energy input measurement for autohydrolysis. The revealed mechanism and method created in this study enable the stepwise separation of gramineae tissues, cells, and major chemical components, enabling a full-composition multi-purpose biorefinery of lignocellulose.
危险品化学品经营许可证（带存储）