Pore wall thickness and interpore influence on adsorption of alkanes in carbons using explicit pore models

Abstract

In modeling of activated carbons, the pores are often assumed to be slit-shaped formed of a constant number of graphene layers. X-ray diffraction studies show that micropores are formed between stacks of different numbers of graphene layers. In this study, we investigate, through the grand canonical Monte Carlo method, the influence on the adsorbed alkanes densities of pore walls with different graphene layers thickness and the related interpore adsorbate interaction when the pore wall has only one graphene layer. All studies of thickness and interpore interaction to date were performed using the Steele 10-4-3 potential model. Instead of Steele model, we propose explicit models made up of graphene layers of discrete carbon atoms. We also investigated the sensitivity of the system to the cut-off and solid-fluid parameter. With our explicit model we found that the influence of the number of carbon layers is not significant for n > 2 as previously observed by Steele model-DFT studies. The system was also insensitive to cut-off and well deep parameter variations. A new pore model with an extra dummy graphene wall was proposed to investigate the interpore interaction. The interpore interaction study with the alkanes series C1 to C4 shows that the retention capacity of heavier alkanes is the same whether for activated carbons with few layers (stronger interpore interaction) as for carbons with two or more layers (stronger solid-fluid interaction) assuming negligible surface mediation. The explicit models proposed can be successfully used in the elaboration of virtual porous carbon models to reproduce wall thickness and interpore adsorbate interactions phenomena.

Grand Canonical Monte Carlo Simulation Experiences of Methane and Ethane Adsorption Behaviors on Simplified Organic Shale Formed by Graphene Layering

“…To conduct a careful investigation and gain a better understanding of the effect of growing planes of graphene sheets in slit-like pore walls on the adsorption behaviors of methane and ethane, GCMC simulations are carried out for one layer (Type-1), two layers (Type-2), three layers (Type-3), and four layers (Type-4) as follows: Initially, the number of available layers in the pore, the cutoff, and the solid–fluid parameter are kept constant, and only the size of the aperture is changed . The adsorption behavior of pure methane or ethane separately on these slits is studied, considering a wide range of apertures (1–4 nm), pressures (1–30 MPa), and temperature (320 K), using Grand Canonical Monte Carlo (GCMC) simulations. Subsequently, the results of simulations for the same apertures are compared to study the effect of the number of graphene layers on the adsorbed gas density for methane and ethane under the same reservoir conditions …”

Valorization of lignocellulosic biomass into sustainable materials for adsorption and photocatalytic applications in water and air remediation

“…VOCs are primarily discharged from industries, such as organic chemicals, printing, and paint, with considerable adverse effects on the environment (Wang et al 2013 ; Liu et al 2019a , b ). The adsorption of VOCs on activated carbons depends on different factors, including the surface area, pore size, and the surface functional groups from one side, and characteristics of volatile molecules such as polarity, weight, and hydrophobicity (Lucena et al 2012 ; Huang et al 2021 ; Rahbar-Shamskar et al 2022 ). Biomass-based activated carbon materials were used as adsorbents to capture VOC materials (Ikram et al 2022 ).…”