A Mimetic Amorphous Active Carbon Model Using Molecular Dynamics Simulation

Abstract

Porous carbons are disordered materials with applications in many areas such as catalysis, molecular separation, and energy storage/conversion. Among porous materials, active carbons are the most popular materials in separation processes. They are non-crystalline materials with heterogeneous pore structures. This property does not permit accurate structural determinations by diffraction techniques. Thus only limited structural information can be extracted from experimental techniques. Consequently, a molecular model of nanoporous carbon can't be constructed that is based solely on experimental data. Computer simulation techniques provide an alternative way to tackle this problem. So, in this study, the synthesis process of an amorphous active carbon is investigated using molecular dynamics simulation. Simulations are carried out at constant temperature in the box containing specific numbers of pure carbon sheets. Two different types of ensembles have been used for simulation includingNPTandNVT. Calculated results show that the final structure of porous carbons is in agreement with SEM images of some commercial active carbons. Also, results indicate that the final structure is consisted of three different pore size (r) zones: r<2 nm which produces micro pores,250 nm which named macro pores. These observations are exactly the same as what is observed in experiments. These various pore sizes especially micro and meso pores are observed in radial distribution function curve, too. At last, the temperature effect on the pore size is investigated. Three different temperatures of 973K, 1073 K and 1173 K are applied for the simulation. Calculated results show that increasing the temperature does not have any significant effects on the pore size and structure.