The role of hydrogen bonding in swelling of coal

摘要

The swelling behavior of coal is different from that of cross-linking polymer, and is affected significantly by the hydrogen bonding between coal and hydroxyl in coal. Since almost all the hydroxyls in coal are phenol type, p-fluorophenol(PFP) is used here as a suitable model compound for coal hydroxyl. The swelling ratio of coal increases proportionally with the heat of hydrogen bonding formation between PFP and the corresponding solvent. Acid treated lignite and alkali/acid treated bituminous coal have higher swelling ratio in polar solvents than that of untreated coal due to the increase of hydroxyl group in coal by these treatment. The swelling ratio of lower rank coal is more sensitive than the higher rank coal to the heat of hydrogen bonding formation of coal-solvent. These evidence show that the hydrogen bonding between coal and solvent is the key factor in determining the swelling behavior of coal in organic solvents.