Abstract The thermal decomposition and products generation characteristics of ammonium thiocyanate (NH4SCN) have been studied in Ar and H2 by thermogravimetry - differential scanning calorimetry, thermogravimetry-Fourier transform infrared spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results show that NH4SCN undergoes four endothermic processes between 40–850 °C in Ar and H2. The first two processes are dominated by the crystal transformation of NH4SCN, melting, and sublimation, and the isomerization of NH4SCN occurred in the third stage due to the pyrolysis process. H2 can inhibit the isomerization slightly and obviously promote the pyrolysis of NH4SCN. The pyrolysis end temperature in H2 was reduced to 603.80 °C, which is 120.55 °C lower than that using an Ar atmosphere. This difference is due to the higher thermal conductivity of H2 than Ar and the participation of H2 in the generation of HNCS and NH3. The main gaseous products are HNCS, NH3, CS2, and H2S. They were found to peak at 240.61 °C, which is 24.62 °C lower than in Ar. Thiourea, guanidine thiocyanate, cyanamide, dicyandiamide and melamine are main intermediates, while graphitic carbon nitride (g-C3N4) was formed at the end of pyrolysis.

中文翻译：

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H 2 中硫氰酸铵热解及其产物形成特性研究

摘要 采用热重-差示扫描量热法、热重-傅里叶变换红外光谱、傅里叶变换红外光谱和X射线衍射研究了硫氰酸铵(NH4SCN)在Ar和H2中的热分解和产物生成特性。结果表明NH4SCN在Ar和H2中在40-850°C之间经历了四个吸热过程。前两个过程以NH4SCN的晶体转变、熔融和升华为主，第三阶段由于热解过程发生NH4SCN的异构化。H2对异构化有轻微抑制作用，明显促进NH4SCN的热解。H2 中的热解结束温度降低到 603.80 °C，比使用 Ar 气氛低 120.55 °C。这种差异是由于 H2 的热导率高于 Ar 以及 H2 参与 HNCS 和 NH3 的生成。主要的气态产品是 HNCS、NH3、CS2 和 H2S。发现它们在 240.61 °C 达到峰值，比 Ar 中低 24.62 °C。硫脲、硫氰酸胍、氰胺、双氰胺和三聚氰胺是主要的中间体，而石墨氮化碳（g-C3N4）在热解结束时形成。