Preparation of aldehyde-functionalized cellulose nanocrystals via aerobic oxidation of cellulose in a recyclable triisopropoxy vanadium oxidation system

Nanocellulose has attracted attention from the scientific community due to its biodegradability and unique physiochemical characteristics. However, the production of high-quality nanocellulose is still limited by the high cost of chemical usage, purification, and energy consumption. In this work, we proposed a catalytic aerobic process for preparing aldehyde-functionalized cellulose nanocrystals by oxidizing cellulose in a triisopropoxy vanadium (VO(OiPr)3)/O2 system and investigated the mechanism of selective oxidation of cellulose in this system. Well-dispersed cellulose nanocrystals with a diameter of approximately 100 nm and an aldehyde content of 0.425 mmol g−1 were obtained under the conditions of 120 °C, 4 MPa O2 pressure, and a 12 h reaction time. The catalyst employed in the oxidation process still retained high activity after being reused four times. This research presents an alternative strategy for the preparation of cellulose nanocrystals with limited chemical usage, which would contribute to the development of environmentally friendly and cost-effective processes for nanocellulose production.