Study on the Adsorption Law of n-Pentane in Silica Slit Nanopores.

Abstract

As the main components of shale, inorganic minerals are important carriers for oil and gas adsorption, whose pore structures and surface properties have significant effects on the fluid adsorption capacity. In this study, slit nanopores (SNPs) were constructed by silica. To investigate the microscopic adsorption law of n-pentane in silica, the grand canonical Monte Carlo (GCMC) method was used to simulate the adsorption behaviors of n-pentane in silica nanoparticles. The effects of different surface wettability, pore size, temperature, and pressure values on the adsorption behavior of pentane were discussed, revealing the micro adsorption mechanism of pentane in silica with different pore sizes and wettability and evaluating the degree of oil and gas utilization. The research results indicate that the adsorption capacity of pentane is greatly affected by the temperature under low-pressure conditions. With the increase of the pore size, the adsorption capacity of pentane increases linearly, and the number of adsorbed pentane molecules gradually decreases. The availability of oil and gas increases, and the oil and gas are more easily extracted. As the surface hydrophobicity of minerals increases, the van der Waals force between minerals and pentane also increases, leading to an increase in the number of adsorbed states of pentane. The stronger the hydrophilicity of the wall, the fewer the pentane molecules adsorbed on the surface, which would improve the efficiency of oil and gas extraction. This study provides potential for the development of novel surfactants based on adsorption selectivity.