Influence of functional groups and pore sizes in porous carbon for methanol acetone adsorptive separation based on molecular simulation

Abstract

In order to investigate the optimal nitrogen functional group and the most suitable pore size for the efficient adsorptive separation of methanol-acetone mixed vapor, a series of theoretical calculations, including Grand Canonical Monte Carlo (GCMC) simulation and density functional theory (DFT) calculation, were carried out to determine the adsorptive separation properties of AC-Rs (AC = activated carbon, R = Pyridinic, -NH 2 , Pyrrolic, Quaternary) with different pore sizes (0.6-8.0 nm). The results showed AC-Pyridinic had the highest methanol-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 hydrogen of methanol's hydroxyl group, and electrostatic interaction between the pyridinic nitrogen and carbon of acetone's carbonyl group were crucial factors for that. In the case of methanol-acetone separation, the methanol molecular aggregation resulted in an increase in methanol-acetone selectivities on AC-Rs. Interestingly, AC-Pyridinic still showed the highest methanol-acetone selectivity. 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.

Size‐Controllable Synthesis of ZIF‐8 and Derived Nitrogen‐Rich Porous Carbon for CO2 and VOCs Adsorption

“…The electrostatic potential (ESP) charges distribution results from Figure 6e–g were obtained using ChelpG charge analysis in Gaussian 09 package [27] . The schematic of pristine graphite, graphite containing pyridinic‐N and pyrrolic‐N functional groups is shown in Figure S5.…”

“…The electrostatic potential (ESP) charges distribution results from Figure 6e-g were obtained using ChelpG charge analysis in Gaussian 09 package. [27] The schematic of pristine graphite, graphite containing pyridinic-N and pyrrolic-N functional groups is shown in Figure S5. Pyridinic-N and pyrrolic-N doping on graphite sheets compare with pristine graphite to study their effect on the surface charge distribution.…”

Hierarchical Nitrogen‐Enriched Carbon from Rationally Designed Polyimide Precursor for Exceptional Acetone Adsorption

“…Therefore, molecular simulations focusing on surface charge distribution were carried out to explore the interaction mechanism of functional groups on acetone adsorption. In brief, the electrostatic potential (ESP) charges were calculated using ChelpG charge analysis in Gaussian 09 package [23] . Perfect graphene sheets were used to simulate the surface of the sample.…”

“…In brief, the electrostatic potential (ESP) charges were calculated using ChelpG charge analysis in Gaussian 09 package. [23] Perfect graphene sheets were used to simulate the surface of the sample. Pyrrole, the selected representative of various func-tional groups due to its abundance, was doped on graphene sheets to study its effect on the surface charge distribution.…”