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Degradation of a Victorian brown coal in sub-critical water

机译：亚临界水中维多利亚州褐煤的降解

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Conversion characteristics of a Victorian brown coal in sub-critical water were investigated. Pulverized brown coal was heated up to 623 K in flowing sub-critical water pressurized at 25 MPa. The total conversion of the coal into extract and non-condensable gas reached over 70 wt percent-daf, which was appreciably higher than the maximum conversion (50 wt percent-daf) with a sub-critical non-hydrogen donor solvent, l-methylnaphthalene (MN). Laser-ionization-desorption mass spectrometry showed that the sub-critical water extract was richer in lower-molecular-mass compounds than the sub-critical MN one. Thus, degradation of the coal occurred more extensively in sub-critical water than in MN. Along with the conversion in sub-critical water, both the total contents of hydrogen and phenolic hydroxyls in the whole products remained nearly unchanged. This suggests comparable and simultaneous formation and decomposition of hydroxyls through hydrolysis of ethers/esters and dehydration condensation between hydroxyls/carboxyls, respectively. For detecting the hydroxyl formation, the coal was first heated at 623 K under an inert gas atmosphere until the formation of water and the other volatiles was completed. Then, the heat-treated coal (LY-H) was exposed to flowing sub-critical water. As expected, the net formation of phenolic hydroxyls from LY-It was detected as 0.8 mmol-OH/g-LY-H while that of hydrogen as 2.3 mmol-H/g-LY-H. Approximately a half of the hydrogen gain was explained as phenolic hydroxyls gain, suggesting the importance of hydrolysis of esters and ethers that formed carboxyls and alcoholic hydroxyls as well as phenolic hydroxyls.
机译：研究了维多利亚褐煤在亚临界水中的转化特性。在压力为25 MPa的亚临界流动水中，将粉状褐煤加热至623K。煤转化为提取物和不可冷凝气体的总转化率达到70 wt％-daf以上，明显高于亚临界非氢供体溶剂l-甲基萘的最大转化率（50 wt％-daf）。 （MN）。激光电离-解吸质谱分析表明，亚临界水提取物中的低分子质量化合物比亚临界MN中的富含。因此，在亚临界水中，煤的降解比在MN中更广泛地发生。随着在亚临界水中的转化，整个产品中氢和酚羟基的总含量几乎保持不变。这表明通过醚/酯的水解和羟基/羧基之间的脱水缩合分别可比较和同时形成和分解羟基。为了检测羟基的形成，首先将煤在惰性气体气氛下在623 K加热，直到水和其他挥发物的形成完成。然后，将热处理过的煤（LY-H）暴露于流动的亚临界水中。如所预期的，从LY-的酚羟基的净形成被检测为0.8mmol-OH / g-LY-H，而氢的净形成为2.3mmol-H / g-LY-H。氢的增加量的大约一半被解释为酚羟基的增加，表明水解形成羧基，醇羟基以及酚羟基的酯和醚的重要性。

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