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在CF_3CFH_2脱HF制三氟乙烯的反应工艺中,如何解决催化剂失活是一个重要的研究难题。在固定床反应器上分别考察Al_2O_3催化剂和经活化的NiF_2/AlF_3催化剂用于CF_3CFH_2脱HF反应的稳定性,其中Al_2O_3催化剂的反应稳定性较差,而在Al_2O_3添加NiO改性并经活化后制备的NiO/Al_2O_3催化剂,其稳定性明显提高。通过X射线衍射(XRD)、N_2吸脱附法(BET)、NH3程序升温脱附(NH_3-TPD)、热重分析法(TG)和激光拉曼光谱(Raman)技术的表征,研究认为Al_2O_3催化剂活性下降的原因是催化剂表面的HF腐蚀作用和结焦双重因素所致。而经HF活化处理的NiO/Al_2O_3催化剂失活的主要原因是它的表面结焦现象。另外,NiF_2/AlF_3催化剂在连续300h反应的稳定性试验中,发现催化剂晶粒的缓慢增长现象,这也是导致催化剂活性下降的次要因素。总之,不同Lewis酸催化剂用于CF_3CFH_2脱HF反应的失活原因主要有三个方面:HF侵蚀、结焦和缓慢烧结。最后,NiF_2/AlF_3催化剂经再生之后,其反应活性恢复比率可达到87.2%。
How to solve the catalyst deactivation is an important research problem in the reaction of trifluoroethylene with CF_3CFH_2 to HF. The stability of Al_2O_3 catalyst and activated NiF_2 / AlF_3 catalyst for CF_3CFH_2 HF removal reaction were investigated on a fixed bed reactor. The reaction stability of Al_2O_3 catalyst was poor, but after Al_2O_3 added NiO was modified and activated, NiO / Al 2 O 3 catalyst, its stability is obviously improved. The properties of Al 2 O 3 (Al 2 O 3) were characterized by X-ray diffraction (XRD), N 2 adsorption and desorption (BET), NH 3 temperature-programmed desorption (NH 3 -TPD), thermogravimetric analysis (TG) and laser Raman spectroscopy The reason for the decrease of the catalyst activity is due to the HF corrosion on the surface of the catalyst and the double factor of coking. The main reason for the deactivation of HF-activated NiO / Al 2 O 3 catalyst is its surface coke formation. In addition, NiF_2 / AlF_3 catalyst in the continuous 300h reaction stability test found that the slow growth of the catalyst grain, which is the secondary factor leading to the decline in catalyst activity. In summary, there are three main reasons for the deactivation of the HF_3CFH_2 removal reaction with different Lewis acid catalysts: HF erosion, coking and slow sintering. Finally, after the regeneration of NiF_2 / AlF_3 catalyst, the reactivity recovery ratio can reach 87.2%.