【摘要】 阐述了用于二氟甲烷(HFC-32)、1,1,1,2-四氟乙烷(HFC-134a)、1,1,1,2,2-五氟乙烷(HFC-125)等ODS替代品合成的铬基催化剂的制备方法 ,讨论了载体、前驱体、铬含量、焙烧气氛、焙烧温度以及助剂等因素对催化剂的比表面积、铬物种引入量、铬物种状态及分散程度的影响以及进而造成对铬基催化剂反应活性及稳定性的影响;分析了铬基催化剂在氟氯交换反应中的失活与催化剂中活性组分流失、晶相转变、表面烧结和积炭之间的关系。指出了目前铬基催化剂在氟氯交换反应中所面临的挑战及展望,认为在真正认识反应的活性中心和反应机制的基础上,提高铬基催化剂的抗积炭、抗烧结能力,加强催化剂的再生工艺,提高催化剂的催化活性,以及延长催化剂的使用寿命等将成为今后氟化工领域研究的方向。更多还原

【Abstract】 Chromium-based materials are the main catalysts for chlorine/fluorine exchange reactions, which are often used for the syntheses of difluoromethane(HFC-32), 1,1,1,2-tetrafluoroethane(HFC-134a), 1,1,1,2,2-pentafluoroethane(HFC-125) and so on. In this paper, the synthetic methods of chromium-based catalysts were reviewed. Meanwhile, the effects of synthetic parameters such as supports, precursors, chromium content, calcination atmosphere, calcination temperature and additives on the surface area, chromium species introduction, state and dispersion degree were discussed, which consequently influenced the catalytic activity and stability of these catalysts. Moreover, the causes of catalyst deactivation with the loss of active species, phase change, sintering and coke deposition were summarized. Finally, the challenges and prospects of chromium-based catalysts for chlorine/fluorine exchange reactions were discussed. It was pointed out that on the basis of real understanding in reaction active center and reaction mechanism,it will be the future research direction in the field of fluorine chemical industry such as improving coke formation resistance and sintering resistance of chrome base catalysts, strengthening regeneration process of the catalysts, improving the catalytic activity of catalysts and extending the service life of catalysts.更多还原