Abstract
The extraction yield of coal in N-methyl-2-pyrrolidinone (NMP)-CS2 mixed solvents was greatly increased from 60% to 85% by adding a small amount of tetracyanoethylene (TCNE). The mechanism of TCNE interaction with coal to increase the coal extraction yield in solvent was investigated based on the spectrum properties of TCNE in NMP. It was found that TCNE does not exist as a neutral molecule in extraction solvent. Instead, TCNE forms 1, 1, 2, 3, 3-pentacyanopropenide anion in NMP. The 1, 1, 2, 3, 3-pentacyanopropenide anion might be responsible for the coal solubility increase.
