The effects of supercritical CO2 on mesopore and macropore structure in bituminous and anthracite coal

By Shiqi Liu, Jingsheng Ma, Shuxun Sang, Tian Wang, Yi Du, Huihuang Fang. Fuel, 2018

138 citations recorded by the source corpus.

Abstract The effects of supercritical CO2 (scCO2) on coal pores play a critical role in CO2 geological storage-enhanced coalbed methane recovery (CO2-ECBM). To investigate the effects of scCO2 on the pore structure and connectivity in coals of different ranks, CO2 sequestration processes were replicated using a scCO2 geochemical reactor. Four coal samples with different ranks were exposed to scCO2 and water for 240 h under 80 °C and 20 MPa. Mercury intrusion porosimetry, nitrogen adsorption tests, and scanning electron microscopy analysis were used to identify the pore volume, pore size distribution, pore connectivity, and pore morphology of the coal samples before and after scCO2-H2O treatment. The increase in the macropore volume caused by the scCO2 is mainly controlled by the pores >30 μm, resulted from the dissolution of carbonate minerals with large grain size in organic matter. The coal rank has a positive influence on the volume and specific surface area of the pores >30 μm, whereas coal rank is more significant for macropore specific surface area in the high-volatile bituminous coal and macropore volume in the low-volatile bituminous, semi-anthracite, and anthracite coal. With an increase in the coal rank, the volume and specific surface area of the mesopores increase. The changes in the mesopore volume in the high-volatile bituminous coal are caused by changes in the pores 20–50 nm in diameter, while these changes in the low-volatile bituminous coal, semi-anthracite, and anthracite are caused by changes in the pores

Subfields: Environmental Engineering, Mechanics of Materials, Ocean Engineering

View Paper: https://www.semanticscholar.org/paper/7b54c22703a1669c79919d0fb11300561e1aa50f