Adjusting surface acidity of hollow mesoporous carbon nanospheres for enhanced adsorptive denitrogenation of fuels

Mesoporous carbons are widely utilized as adsorbents for adsorptive removal of nitrogen-containing compounds in fuel. Herein, hollow mesoporous carbon nanospheres (HMCNs) were successfully synthesized via a facile silica-assisted sol–gel strategy and further oxidized by different acids (HNO 3 , H 2 SO 4 , and (NH 4 ) 2 S 2 O 8 ) to adjust their surface chemistry. The HMCNs oxidized with (NH 4 ) 2 S 2 O 8 contain the most oxygen-containing groups and exhibit the strongest acidity, resulting in high adsorption capacities towards quinoline (QUI, 29.78 mg N ·g −1 ) and indole (IND, 26.59 mg N ·g −1 ) in model fuel. The superior performance is attributed to the acid-base interaction and hydrogen bonding interaction between the adsorbent and QUI/IND molecules. Remarkably, the adsorption capacity towards nitrogen-containing compounds in real diesel is as high as 19.19 mg N ·g −1 at 50 °C. Our work has paved the way to the rational design and synthesis of high-performance adsorbents for the removal of nitrogen-containing compounds in real diesel on a large scale.