TBD-grafted activated carbon as an efficient solid base catalyst for continuous Knoevenagel reaction

• A novel chloromethylation method for activated carbon modification is applied. • TBD-grafted activated carbon is used for Knoevenagel reaction . • A continuous-flow processing based on micro-packed bed reactor is established. • The catalyst shows a higher TOF (147.7 h −1 ) than other in literature. The development of a highly efficient and stable metal-free solid base catalyst for the Knoevenagel reaction remains a significant challenge. In this study, activated carbon is selected as support material to develop a new base catalyst due to its excellent chemical stability. A novel surface chloromethylation method is applied to modify the activated carbon surface, followed by covalent grafting of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), resulting in a highly effective solid organic base catalyst. A continuous platform based on a micro-packed bed reactor has been optimized for the Knoevenagel reaction. The system achieves excellent space-time yields (19129.4 g P r o k g c a t - 1 h - 1 ) and demonstrates a broad substrate scope. The solid organic base catalyst exhibits a turnover frequency ( TOF ) exceeding 140 h - 1 , surpassing the performance of similar nitrogen-based catalysts reported in literature (7.6–68.0 h - 1 ). Moreover, the catalyst shows no signs of deactivation after more than 23 h of continuous operation with a turnover number ( TON ) exceeding 115, indicating comparable performance reported in literature (29.7–297.2). Catalyst deactivation is primarily attributed to the adsorption of raw materials and products onto the base sites, leading to a gradual loss of catalytic activity.