Adsorption-Separation Of Volatile Organic Gases On Nitrogen Nano-Porous Carbon:A Grand Canonical Monte Carlo Simulation

Methanol,acetone and their mixtures are important reaction media,which are widely used in both chemical industry and organic chemistry.Their volatilization will cause great harm to indoor and outdoor environment,as well as the human health.Therefore,this paper took the recovery and utilization of both and their mixtures as the starting point of the problem.The effects and rules of nitrogen functionalization on the methanol-acetone adsorptive separation performance of porous carbon were explored by Grand Canonical Monte Carlo(GCMC)and density function theory(DFT).On this basis,the optimal nitrogen functional groups and pore size for efficient methanol-acetone adsorptive separation were determined,and their influence mechanisms were analyzed.The results showed AC-Pyridinic had the highest methanol and acetone adsorption capacities(14.64 mol/kg for acetone and 26.35 mol/kg for methanol at their respective saturation pressures).The high adsorption energies,the hydrogen bonding interaction between the pyridinic nitrogen and a hydrogen of methanol’s hydroxyl group and electrostatic interaction between the pyridinic nitrogen and a carbon of acetone’s carbonyl group were crucial factors for that.In the case of methanol-acetone separation,AC-Pyridinic still showed the highest methanol-acetone selectivity.Combined with the visualization of competitive adsorption process and the DFT calculation of multi-molecule adsorption on porous carbons,the separation mechanism was analyzed.The results showed the methanol molecular aggregation resulted in an increase in methanol-acetone selectivities on AC-Rs.Furthermore,the pore with 3.5 nm and 3.0 nm were optimal for methanol and acetone adsorption respectively,in which AC-Pyridinic exhibited superior capture capacities(23.19 mmol/g for methanol at 16 kPa and 11.64 mmol/g for acetone at 30 kPa).And with a 6 nm pore size,AC-Pyridinic had the highest selectivity(～5.0).The mesopore of 2.5-3 nm is suitable for methanol-acetone adsorptive separation taking both adsorption and selectivity performance into consideration.This investigation predicted the functional group and pore sizes with the best modification effect on AC for methanol-acetone adsorptive separation,which sheds light on ways to design a highly efficient adsorbent for gas adsorption and separation.