An evidence for the strong association of N-methyl-2-pyrrolidinone with some organic species in three Chinese bituminous coals

Three Chinese bituminous coals collected from Shenfu, Heidaigou and Feicheng coal fields were respectively extracted with carbon-disulfide/N-methyl-2-pyrrolidinone (CS2/NMP) mixed solvent (volume ratio 1:1) at room temperature followed by distillation of CS2 under ambient pressure and subsequent removal of most of NMP by distillation at 110°C under reduced pressure to afford mixed solvent-extractable fractions (MSEFs) with small amount of NMP. Acetone-extractable fraction 1 (AEF1) was obtained by extracting each MSEF under ultrasonic irradiation at room temperature and subsequently using a Soxhlet extractor. Direct extraction of each bituminous coal affords acetone-soluble fraction 2 (AEF2). GC/MS analysis shows that m/z of base or secondary peak in mass spectra of a series of components from each AEF1 is 98, whereas such components were not detected in AEF2. Since m/z of base peak in mass spectrum of NMP itself is 99, the base or secondary peak at m/z 98 should result from loss of α-H from NMP, i.e., NMP is strongly associated with some organic species (OSs) and thereby the components detected with base or secondary peak at m/z 98 in their mass spectra should be associated NMP-OS. Supported by the National Natural Science Foundation of China (Grant Nos. 90410018, 90510008 and 10432060), the Key Project of Chinese Ministry of Education (Grant No. 104031) and the Program of the Universities in Jiangsu Province for Development of High-Tech Industries (Grant No. JHB05-33)