Abstract Nitrogen-containing porous carbonaceous materials based on chitosan were successfully prepared by hydrothermal carbonization (HTC) followed by thermal treatments at different temperatures. A detailed characterization of structure, porosity, and chemical composition of these carbonaceous materials was done by X-ray diffraction, scanning electron microscope, thermogravimetric analysis, Raman and infrared spectroscopies, nitrogen adsorption-desorption isotherms, and CHN elemental analysis techniques. Low structural order like amorphous carbons, low porosity, and various functional groups were observed for the precursor hydrochar (obtained from hydrothermal carbonization of chitosan). When this precursor was thermally treated from 200 to 800 °C it was possible to understand its structural transformations due to the changes in the vibrational properties. These results indicate that an increase in the temperature of the thermal treatment promotes an increase in the graphitization degree of the carbonaceous materials. However, it leads to the formation of a defective graphitic-type structure. Furthermore, it was observed an increase in the meso- and micropores up to 600 °C, affecting considerably the porosity and, consequently, the specific surface area of these materials. However, this porous structure can collapse when the treatment temperature increases to 700 and 800 °C. Also, the prepared carbonaceous materials showed high nitrogen content for all temperature interval, and the morphology of the particles was not strongly affected. Our results suggest that thermal treatments of hydrochars are suitable to prepare carbonaceous materials with controlled compositional, structural and textural properties and containing a high nitrogen content.

中文翻译：

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来自水热处理生物质的有序多孔碳：热处理对结构和孔隙率的影响

摘要 通过水热碳化（HTC）和不同温度的热处理，成功制备了基于壳聚糖的含氮多孔碳质材料。这些碳质材料的结构、孔隙率和化学成分的详细表征是通过 X 射线衍射、扫描电子显微镜、热重分析、拉曼和红外光谱、氮吸附-解吸等温线和 CHN 元素分析技术完成的。前体水碳（从壳聚糖的水热碳化获得）中观察到低结构有序，如无定形碳、低孔隙率和各种官能团。当这种前体在 200 至 800 °C 下进行热处理时，可以理解由于振动特性的变化而导致的结构转变。这些结果表明热处理温度的增加促进了碳质材料的石墨化程度的增加。然而，它导致形成有缺陷的石墨型结构。此外，观察到中孔和微孔增加到 600 °C，显着影响孔隙率，从而影响这些材料的比表面积。然而，当处理温度升高到 700 和 800 °C 时，这种多孔结构会坍塌。此外，制备的碳质材料在所有温度区间都显示出高氮含量，并且颗粒的形态没有受到强烈影响。我们的研究结果表明，氢化碳的热处理适合制备具有受控成分、结构和质地特性并含有高氮含量的碳质材料。