TEMPO immobilization on activated carbon by a novel surface-formylation tactic for long-term aerobic oxidation of alcohols

2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) has vital applications in the field of multiphase reaction, especially for the aerobic oxidation of alcohols. Activated carbon (AC) has a porous structure, rigid surface property, and low cost, which was the prominent carrier for TEMPO immobilization to produce the heterogeneous catalyst. However, the brilliant strategy of TEMPO immobilization on AC for long-term aerobic oxidation of alcohols was still challenging. In this work, surface-formylation and reductive amination were conducted to achieve the covalent TEMPO grafting on AC, which opened up a novel routine for surface modification and preparing heterogeneous catalysts based on carbon materials. The catalysts were packed in a micro-packed bed reactor to perform continuous aerobic oxidation of various alcohols. The catalytic performance of benzyl alcohol to benzaldehyde (turnover number: 1160.6, turnover frequency: 99.6 h −1 ) was much superior to those in the literature by using covalently grafted heterogeneous TEMPO catalysts.