Green Chemical Engineering Research Center, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China.
Green Chemical Engineering Research Center, Shanghai Advanced Research Institute, University of Chinese Academy of Sciences, Beijing 100049, China.
Molecules. 2021 Apr 28;26(9):2568. doi: 10.3390/molecules26092568.
Microwave (MW) heating was proven to efficiently solid-synthesize calcium carbide at 1750 °C, which was about 400 °C lower than electric heating. This study focused on the investigation of the diffusion behaviors of graphite and calcium oxide during the solid-state synthesis of calcium carbide by microwave heating and compared them with these heated by the conventional method. The phase compositions and morphologies of CaO and C pellets before and after heating were carefully characterized by inductively coupled plasma spectrograph (ICP), thermo gravimetric (TG) analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that in both thermal fields, Ca and C inter-diffused at a lower temperature, but at a higher temperature, the formed calcium carbide crystals would have a negative effect on Ca diffusion to carbon. The significant enhancement of MW heating on carbon diffusion, thus on the more efficient synthesis of calcium carbide, manifested that MW heating would be a promising way for calcium carbide production, and that a sufficient enough carbon material, instead of CaO, was beneficial for calcium carbide formation in MW reactors.
微波（MW）加热被证明可以有效地在 1750°C 下固相合成电石，比电热法低约 400°C。本研究重点研究了在 MW 加热和传统加热下，石墨和氧化钙在电石固相合成过程中的扩散行为。通过电感耦合等离子体光谱仪（ICP）、热重（TG）分析、X 射线衍射（XRD）、扫描电子显微镜（SEM）和 X 射线光电子能谱（XPS）对加热前后的 CaO 和 C 颗粒的物相组成和形貌进行了仔细的表征。实验结果表明，在两种热场中，Ca 和 C 在较低温度下相互扩散，但在较高温度下，形成的碳化钙晶体对 Ca 向碳的扩散有负面影响。MW 加热对碳扩散的显著增强，从而对更高效的电石合成产生了积极的影响。这表明 MW 加热将是一种有前途的电石生产方法，并且在 MW 反应器中，足够数量的碳材料而不是 CaO 有利于碳化钙的形成。
