Kaolinite, a natural, layered phyllosilicate, has been used as the solid catalyst for the hydrolysis of cellulose in our previous work. In the present study, kaolinite was activated by mineral acid and further evaluated for the hydrolysis of cellulose in water. The acid-activated kaolinite was characterized by XRF, XRD, FT-IR, BET and TG. The effects of reaction temperature, reaction time, mass ratio and water amount were investigated in the system. It was found that the highest total reducing sugars (TRS) yield of 50.2% was obtained on the kaolinite activated by 20% HNO3 with the mass ratio of catalyst to cellulose of 0.2 and water to cellulose of 14 at 205 ℃ for 3 h. Moreover, the catalyst was easily regenerated by calcination and the yield of TRS on the regenerated catalyst changed between 50.2% and 45.2% after four times reuse. The results showed that the acid activation could influence the crystallinity and improve the specific surface area, but the high TRS yield of the activated kaolinite should be ascribed to the increasing of the interlayer Al–OH groups and the formation of inner hydrogen bonds between the octahedral sheets and tetrahedral sheets. Finally, it was suggested that this was the effective way for improving the catalytic performance by increasing the interlayer Al–OH groups on the kaolinite catalyst.

中文翻译：

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无机酸活化高岭土上纤维素的强化水解还原糖

高岭石是一种天然的层状页硅酸盐，在我们以前的工作中已被用作纤维素水解的固体催化剂。在本研究中，高岭石被无机酸活化，并进一步评估纤维素在水中的水解。通过XRF、XRD、FT-IR、BET和TG对酸活化高岭石进行了表征。考察了反应温度、反应时间、质量比和水量对体系的影响。结果表明，在20% HNO3活化、催化剂与纤维素质量比为0.2、水与纤维素质量比为14的条件下，在205℃下反应3 h，总还原糖(TRS)收率最高，达到50.2%。此外，该催化剂易于通过煅烧再生，再生催化剂的TRS产率在4次重复使用后变化在50.2%至45.2%之间。结果表明酸活化可以影响结晶度并提高比表面积，但活化高岭石的高TRS产率应归因于层间Al-OH基团的增加和八面体之间的内部氢键的形成。片和四面体片。最后，有人提出这是通过增加高岭石催化剂上的层间Al-OH基团来提高催化性能的有效途径。