13C-NMR分析混合酸处理脱灰对永兴褐煤结构的影响

运用煤的结构化学理论和固态 ¹³C-NMR的研究方法,对比分析了永兴褐煤在混合酸处理脱灰前后碳组成的变化。研究表明,混合酸处理脱灰对永兴褐煤中脂肪碳和芳香碳两者比例分配的影响并不大,但对季碳、环内氧接脂碳、芳香桥碳和羧基碳的破坏作用比较明显;在芳香桥碳锐减的同时,芳甲基的比例非但没有减少反而略有增加,表明永兴褐煤中的双环及多环结构被破坏为单环结构,芳香簇的尺寸变小了,这是混合酸处理脱灰对永兴褐煤结构最重要的影响。

13C-NMR study on effect of demineralization by mixed acid treatment on Yongxing lignite structure

Based on the theory of coal structure chemistry, the carbon composition differences between Yongxing lignite and its demineralized sample were comparatively studied with solid state ¹³C-CP/MAS NMR analysis. The results show that the impact of mixed acid treatment demineralization on the allocation proportion of aromatic carbons and aliphatic carbons is insignificant, but its destructive effects on quaternary carbon, aliphatic carbon bonded to oxygen in cyclic hydrocarbon, aromatic bridgehead carbon and carboxyl carbon are more apparent. While aromatic bridgehead carbon is depleted, the proportion of aromatic methyl does not decrease but slightly increases simultaneously. This indicates that the double/multi-ring structures are destroyed into single-ring ones and the aromatic cluster size shrinks, which is the most critical influence of demineralization by mixed acid treatment on Yongxing lignite structure.