Abstract Lignites show great potential as feedstock for the production of valuable carboxylic acids by mild oxidation. In this study, valuable aromatic polycarboxylic acids were produced from Xianfeng lignite-derived residue (XLDR) through mild oxidation in green aqueous H2O2 solution. The results show that XLDR oxidation can produce benzene carboxylic acids (BCAs) and polycyclic aromatic carboxylic acids (PCACAs) in high selectivity. The BCAs are dominated by mellitic acid and benzenepentacarboxylic acid with 55.5% and 13.3% in the total yield of all group components based on the analysis with gas chromatography/mass spectrometer. Moreover, three series of PCACAs with an aliphatic ring were identified by direct analysis in a real-time ionization source coupled to a time-of-flight mass spectrometer. The BCAs and PCACAs could be generated from different kinds of aromatic structures via oxidation by OH produced from H2O2.

中文翻译：

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咸丰褐煤残渣在 H2O2 水溶液中温和氧化选择性生产芳族羧酸及表征

摘要 褐煤作为通过温和氧化生产有价值的羧酸的原料显示出巨大的潜力。在这项研究中，通过在绿色 H2O2 水溶液中温和氧化，从咸丰褐煤衍生残渣 (XLDR) 中生产有价值的芳香族多元羧酸。结果表明，XLDR氧化可以高选择性地产生苯羧酸（BCA）和多环芳族羧酸（PCACA）。根据气相色谱/质谱分析，BCA以苯六甲酸和苯五甲酸为主，各组组分的总收率分别为55.5%和13.3%。此外，通过在与飞行时间质谱仪耦合的实时电离源中进行直接分析，鉴定了三个系列的具有脂肪族环的 PCACA。