杂多酸催化水解纤维素纤维提升溶解浆黏度控制和反应性能

Improvements of the Viscosity Control and Reactivity of Dissolving Pulp by Using Heteropoly Acid-based Catalytic Hydrolysis of Cellulose Fibers

采用4种典型的Keggin型杂多酸,即磷钨酸(PTA)、硅钨酸(STA)、硅钼酸(SMA)和磷钼酸(PMA)处理溶解浆纤维,通过对比浆料特性黏度变化,确定PTA较优处理条件为:H+浓度0.01 mol/L,温度90℃,处理时间30 min;通过对比4种杂多酸处理对溶解浆纤维微观形貌结构、孔径、孔体积和保水值等参数的影响,发现PTA处理优于其他3种杂多酸处理。相应地,经PTA处理后,溶解浆黏度可控性和反应性能提升最为显著,浆料黏度由561 mL/g降至437 mL/g,反应性能由49.1%增至74.1%。回用实验结果表明,回用1次时,PTA、STA和PMA回收率均在87%以上,SMA回收率为83.6%,且回用的杂多酸催化活性基本保持不变。其中,PTA具有较高的化学稳定性,循环6次后仍能保持87.1%的回用率,具有优异的可回收性和再利用性。

In this work,four typical Keggin-type heteropoly acid(HPA),including phosphotungstic acid(PTA),silicotungstic acid(STA),silimolybdic acid(SMA)and phosphomolybdic acid(PMA)were used to activate the PHK-based dissolving pulp.Through compar‐ing the changes of the intrinsic viscosity of the pulp optimized the treatment conditions were H+concentration of 0.01 mol/L at 90℃for 30 min.Based on the changes of fiber accessibility in terms of micro morphology and structure,pore size,pore volume and water retention val‐ue,it was evident that PTA treatment was better than other treatments.As a result of optimized PTA treatment,the viscosity of the resultant dissolving pulp reduced from 561 mL/g to 437 mL/g and the reactivity correspondingly increased from 49.1%to 74.1%,which was the most significant one.The recovery rates of these HPAs were very high,more than 87%for PTA,STA and PMA,and 83.6%for SMA when the first recycling.Moreover,among those HPAs,PTA had the highest chemical stability,recyclability and reusability,and maintained a reuse rate of 87.1%after recycling six times.