Effect of nitrogen-doped activated carbon on formaldehyde adsorption behaviour in different scale pores

[Display omitted] •Nitrogen-doped does not broaden the optimal pore size for CH2O adsorption.•Mechanism of adsorption by nitrogen-doped with different pore sizes are clarified.•The limiting pore size of activated carbon adsorption CH2O is 14 Å.•Nitrogen-doped have ability to increase the limiting pore size to 16 Å. The pore size range of activated carbon has an important effect on formaldehyde adsorption, while nitrogen-doped can promote formaldehyde adsorption, but the mechanism of nitrogen-doped on formaldehyde adsorption at different pore size range has not been elaborated clearly. Therefore, this paper investigates the effect of range on formaldehyde adsorption at different pore size scales. Through simulation, it is concluded that nitrogen-doped does not broaden the optimal pore size for formaldehyde adsorption and the optimal pore size is still 6 Å, but nitrogen-doped can improve the non-bonding interactions between formaldehyde molecules and activated carbon by changing the electrostatic distribution on the surface of activated carbon, which enhances the adsorption of formaldehyde molecules. In addition, the non-bonding interaction between formaldehyde molecules and activated carbon decreases with increasing pore size, whereas nitrogen-doped enhances the non-bonding interaction between formaldehyde molecules and activated carbon, and therefore nitrogen-doped improves the limiting pore size of activated carbon for formaldehyde adsorption.