Adsorption induced deformation in graphitic slit mesopores: A Monte Carlo simulation study

Abstract

A grand canonical Monte Carlo simulation study of argon adsorption in deformable graphitic slit mesopores has been carried out, to determine the mechanisms of deformation in the different stages of adsorption and desorption. At pressures less than the condensation pressure, especially in the submonolayer coverage region, the pore walls are slightly compressed. This is due to the decrease in the potential energy of interaction between the adsorbate and the second graphene layer (the interaction with the outermost graphene layer remains the same) and this enhancement of the solid-fluid interaction compensates for the repulsive penalty incurred by compressing of the graphene layers. This mechanism holds, irrespective of pore size and temperature, because at low loadings the two pore walls behave like two independent surfaces. At higher loadings, after condensation has taken place, adsorbate molecules in the interior of the pore attract the pore walls, while those close to the 2 surface repel them. As a result the pore can either contract or expand at high loadings, depending on the balance between these two mechanisms. Across the capillary condensation, the attraction of the condensate in the pore interior is greater than the repulsion by the adsorbate close to the surface, resulting in pore contraction and a corresponding sharp decrease in the solvation pressure. After the capillary condensation, the pore either expands or contracts, depending on the balance between these two processes, which is a function of pore width and temperature, which in turn determine the commensurate or incommensurate packing and thermal motion of the molecules.

Molecular Simulation of Sorption-Induced Deformation in Atomistic Nanoporous Materials

“…Moreover, the results by Long et al also show that the pressure tensor differs in normal and longitudinal directions, indicating an anisotropic deformation pattern. Similar high in-pore pressure and related deformation are also given by other works employing either the GCMC method 30,31 or DFT. 15,32 However, a great limitation of works stated above is that the pore systems built are not deformable, thus one can only deduce the deformation by assuming a mechanical constitutive relationship (Hooke's law for instance).…”

Ti3C2 MXene Paper for the Effective Adsorption and Controllable Release of Aroma Molecules

“…However, the weak original (002) peak is still present in the XRD spectra, which could be attributed to the residual nanosheets that are not intercalated with PA. According to the work of Diao et al on slit pore deformation, the expansion of interlayer space is thought to be induced by the positive solvation pressure before capillary condensation of molecules in the mesopores, thus, leading to the deformation of interlayer space. The graphene paper as a reference material was subjected to the same PA adsorption process for comparison.…”

Deformation of Shale and Coal Organic Carbon Slit Micropores Induced by CO2-Enhanced Gas Recovery: A Monte Carlo Simulation Study

“…The micropores of shale organic matter and coal were modeled as carbon slit pores. The pore is composed of two fixed outermost carbon layers and a number of inner carbon layers that can move normal to the pore walls. , …”

“…The SS interaction energy between two carbon layers was calculated by integrating the interaction between a carbon atom and a carbon layer from the Bojan−Steele equation, with the details described in. 60, 61 2.2. Monte Carlo Simulation.…”

“…In this work, the GCMC simulation was performed with an in-house Monte Carlo algorithm written in Fortran. 60,61 Figure 1 shows the schematic diagram of the simulation box for the shale and coal organic carbon slit pore. The dimension of the simulation box was set as 10 times the collision diameter of CH 4 in the x direction.…”