Development of biochar supported bifunctional UiO-66 catalyst and its application for 5-HMF production from cellulose

Metal-organic frameworks (MOFs), particularly UiO-66, offer advantages in biomass catalytic conversion due to their good thermal stability, tunable porosity and abundant active sites. However, agglomeration limits their catalytic efficiency. To address this, a series of acid-base bifunctional UiO-66-type catalysts supported on biochar (BC) was developed in green solution through a one-pot method. BC prepared by pyrolyzing cotton stalks (CS) under N 2 atmosphere at high temperature and activated before use. The physico-chemical properties of materials were studied by various characterization methods, and their catalytic performance for converting cellulose to 5-hydroxymethylfurfural (5-HMF) in [BMIM]Cl ionic liquid was evaluated. Reaction parameters such as catalyst type, catalyst loading, temperature and time were optimized. Under the optimized conditions, achieving a 5-HMF yield of 46.58 %. The BC-supported catalyst NH 2 -UiO-66-SO 3 H/BC exhibited significantly higher catalytic activity than its unsupported counterpart and increased the 5-HMF yield by 23.78 %. This performance improvement is attributed to the grafted sulfonic/amino groups, which enhance the catalytic performance by improving the dispersion of UiO-66 upon the introduction of BC. This work demonstrates biochar-supported UiO-66 as an effective strategy for enhancing catalytic efficiency in sustainable biomass valorization to platform chemicals.