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利用傅里叶红外光谱分析技术对煤化程度(R_O)范围为0.35%~5.32%的19个煤样进行了结构分析。分析结果表明:随着R_O值的增加,煤结构中不同的官能团具有不同的演化规律。芳环结构中C-H键在红外谱图中先增加,当R_O>3.0%后逐渐减小。含氧侧链与脂肪族侧链随着R_O值增加,吸收峰强度总体呈减弱的趋势。含氧官能团的含量在逐渐的减少,R_O>2.5%时,煤结构中基本不再含有含氧侧链;脂肪族侧链R_O<2.0%时,脂肪侧链随着煤化程度的增加快速减少,R_O>2.0%时脂肪族侧链在煤结构中缓慢减少,当R_O>2.5%时,在煤结构中检测到的脂肪侧链已经很少。煤结构的上述演化规律预示着煤在不同的演化阶段具有不同的生气特征。R_O<0.8%含氧侧链在煤结构的快速减少说明CO_2气的生成主要发生在相对低的演化阶段;脂肪侧链两段式的演化规律说明煤的主要生气(烃类气体)阶段发生在R_O<2.0%,而煤生气结束的煤化程度界限为R_O>5.0%。煤在石墨化过程中从芳环上脱落的氢与煤在演化阶段生成的CO_2之间发生的费—托反应可能是过成熟阶段煤成气碳同位素倒转(反转)的一个重要因素。
The structure of 19 coal samples with a range of R_O ranging from 0.35% to 5.32% were analyzed by Fourier transform infrared spectroscopy. The results show that with the increase of R_O value, different functional groups in coal structure have different evolutionary rules. C-H bond in the aromatic ring structure first increased in the infrared spectrum, when R_O> 3.0%, gradually decreased. Oxygen side chains and aliphatic side chains with increasing R_O value, the absorption peak intensity generally showed a weakening trend. The contents of oxygen-containing functional groups decreased gradually. When R_O> 2.5%, the oxygen-containing side chains were almost no longer contained in the coal structure. When the aliphatic side chains R_O <2.0%, the aliphatic side chains decreased rapidly with the increase of the degree of coalification, When R_O> 2.0%, the aliphatic side chains slowly decreased in the coal structure. When R_O> 2.5%, there were few aliphatic side chains detected in the coal structure. The above evolutionary rules of coal structure indicate that coal has different angry characteristics in different evolution stages. R_O <0.8% The rapid reduction of oxygen-containing side chains in the coal structure indicates that the generation of CO_2 gas mainly occurs at a relatively low stage of evolution. The evolution of the two-stage fat side chain indicates that the major gas-producing stage of the coal occurs at R_O <2.0%, while the limit of coalification at the end of coal gasification is R_O> 5.0%. The Fischer-Tropsch reaction between hydrogen released from the aromatic ring of coal and CO 2 generated by coal during the graphitization process may be an important factor for reversing (reversing) the carbon isotope of coal-forming gas during the overriding stage.