Research On the Fractal Dimensions of the Organic-Rich Shale Pores Via Different Models

Fractal dimension can be used to the pore surface characterize. For pore structures in different sizes, the calculation models of fractal theory should be distinguished due to the different principles of the gas adsorption experiments. To further study the adaptability of the fractal model for gas adsorption experimental data, the author collected shale samples of Longmaxi formation from Well JY1, then CO2 and N2 adsorption provided the PSD curves. In addition, the fractal dimensions of micropore and mesopore were calculated by the Jaroniec fractal model and Frenkel–Halsey–Hill (FHH) fractal model respectively. The research shows that the Jaroniec model may be suitable to calculate CO2 adsorption data and could characterize the fractal dimension of micropore, while the FHH model may be suitable to calculate N2 adsorption data in the high relative pressure region. It suggests that the micropore and mesopore could have different dimensions and the evaluation of the structure in shale pores should consider both of them.

NITROGEN, WATER AND BENZENE ADSORPTION IN MESOPOROUS CARBON (CMK-1) AND COMMERCIAL ACTIVATED CARBON (NORIT SX22)

Adsorption at various interfaces has attracted the attention of many scientists. This article discusses gas-solid and vapour-solid adsorption in CMK-1 and Norit SX22 using nitrogen, water and benzene as adsorbates. For comparison, MCM-48 used as template in synthesizing CMK-1 was also utilized as adsorbent. Results showed that the shape of nitrogen isotherm for CMK-1 is categorized as Type IV shape, whereas activated carbon (Norit SX2) has Type I shape with a hysteresis loop at P/P0 > 0.5, which is a H4 type of hysteresis. The shape of nitrogen isotherm for MCM-48 is categorized as Type IV shape with small hysteresis loop observed at P/P0 above 0.45, indicating that the larger pores are filled at high P/P0, which is typical of an H3 hysteresis loop The amount of nitrogen adsorbed in activated carbon at the high relative pressure is considerably smaller than that in CMK-1. The hydrophobicity feature of CMK-1 is the same as activated carbon (Norit SX2), but slightly different to the template MCM-48. The affinity of CMK-1 to benzene is considerably higher than activated carbon, suggesting the promising future of CMK-1 to be used as a selective adsorbent for the removal of organic compounds from water environment. Keywords: Adsorption, water, benzene, CMK-1, activated carbon