长期以来, 学者们致力于将玉米秸秆这类低品位的生物质资源向高附加值的化学品转化, 提高其利用价值。 对玉米秸秆进行常压酸催化多元醇液化试验, 并对其所得液化残渣的主要组成成分、 热解及纤维特性进行研究。 采用傅里叶红外光谱技术(FTIR)、 热裂解气相色谱-质谱联用技术(Py-GC/MS)、 热重分析技术(TGA)、 X射线衍射技术(XRD)及扫描电子显微镜技术(SEM)对玉米秸秆及其液化残渣的化学基团、 热裂解产物、 热失重情况、 晶体结构和微观形貌进行了检测分析。 FTIR分析表明, 液化残渣中三组分(纤维素、 半纤维素和木质素)官能团的特征吸收峰几乎消失, 其主要含有未液化完全的纤维素和三组分降解产生的小分子间通过聚合反应生成的大分子物质。 Py-GC/MS表明, 液化残渣热裂解产物中包含呋喃类(10.64%)、 酚类(18.89%)、 酮类(3.73%)、 烃类(35.23%)、 醇类(4.17%)、 醛类(4.31%)、 醚类(1.25%)和有机酸类(4.79%)及含S或N杂原子化合物(17.00%)等89种可识别的有机物, 这些有机物的含碳数高于玉米秸秆同类族化合物中的含碳数。 通过TGA明确液化残渣热失重的情况, 即加热阶段, 其质量损失约为3%; 快速失重阶段, 质量损失非常明显, 约为45%; 缓慢失重阶段, 质量损失不足4%; 其发生热解的条件比玉米秸秆的更为苛刻。 XRD结果可知, 液化残渣的主峰和次峰消失, 破坏了纤维素Ⅰ晶格结构, 形成球磨纤维素。 SEM图像表明, 玉米秸秆经酸催化多元醇液化后生成杂乱无序、 粗糙、 不规则、 呈颗粒状的液化残渣。 综上, 此条件下玉米秸秆几乎完全液化。 这为液化残渣制备木质基炭材料给予理论基础与应用支持, 促进了生物质资源全组分利用。

Researchers have been committed to transforming low-grade biomass resources, such as corn stalks, into high-value chemicals to improve their utilization value. Therefore, it is very significant to carry out the liquefaction of corn stalks in the presence of polyhydric alcohols with an acid catalyst at atmospheric pressure and study the main components, pyrolysis and fiber properties of the liquefaction residue. In this paper, the chemical groups, pyrolysis property, thermogravimetric loss, crystal structure, and microstructure of corn stalk and its liquefaction residue were analyzed by Fourier transform infrared spectroscopy (FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), thermogravimetric analysis (TGA), X-rays diffraction (XRD), and scanning electron microscopy (SEM). FTIR analysis results showed that the characteristic absorption peaks of three components (cellulose, hemicellulose and lignin) in liquefaction residue almost disappeared. It was mainly large molecules produced by interactions of some small molecules produced by the degradation of three components and incompletely degraded cellulose. Py-GC/MS showed that 89 kinds of organic compounds could be identified in pyrolysis products of liquefaction residue, including furans (10.64%), phenols (18.89%), ketones (3.73%), hydrocarbons (35.23%), alcohols (4.17%), aldehydes (4.31%), ethers (1.25%), organic acids (4.79%) and heteroatom-containing compounds (17.00%). The carbon number of these organic compounds was higher than that of similar compounds in corn stalks. TGA analyzed the thermal weight loss of liquefaction residue. In the heating phase, the rapid weightlessness phase and the slow weightlessness phase, the mass loss was about 3%, 45%, and 4%, respectively. Its pyrolysis conditions were more severe than those of corn stalks. Results from XRD revealed that the main and secondary peaks of liquefaction residue disappeared, destroyed the cellulose I latticed and formed an amorphous structure. In addition, from SEM characterization results, the liquefaction residue exhibited a disorganized, rough, irregular, and granulated morphology. In conclusion, the corn stalk’s fibrous structure was destroyed and liquefied under this liquefaction condition. The theoretical foundation and technical support could be provided for preparing wood-based carbon materials from liquefaction residue and then promoted the high value-added utilization of biomass resources.