乙炔氢氯化用钌催化剂概况

随着“水俣公约”的约束及国家环保法规日益严格,开发新型高效的无汞催化剂已成为乙炔法聚氯乙烯产业可持续发展的迫切需求。本文概述了近年来钌基催化剂的研究进展,探讨了钌基催化剂工业化测试数据,综述了对应的废催化剂回收工艺,分析并对比了钌催化剂工业化应用的经济性。分析认为,提高钌基催化剂的使用寿命同时降低回收成本是提高钌基催化剂工业化应用潜力的关键。     

乙炔氢氯化反应无汞贵金属催化剂的研究进展

受“水俣公约”和环境保护政策约束,研究和开发新型无汞催化剂是保障我国乙炔法制备聚氯乙烯未来发展的核心环节。无汞催化剂包括贵金属催化剂、非贵金属催化剂和非金属催化剂,其中贵金属催化剂被认为是最具有工业化应用前景的催化剂。本文概述了近年来国内外乙炔氢氯化贵金属Au、Ru、Pd和Pt催化剂的研究进展,重点综述了不同催化剂的活性组分、催化机理及催化剂的改性方法等方面的研究,分析了不同改性方法的作用机制及不同催化剂改性的研究方向。研究表明,添加助剂或多金属复配、配体和离子液体的使用及载体改性均使贵金属催化剂的催化活性和稳定性得到一定程度提高,从而进一步增加了贵金属催化剂工业化应用的可能性。     

In-silico vinyl chloride suspension polymerization: Kinetic modelling,thermal runaway prediction,and prevention

In the present study, a combined kinetic and heat transfer model was developed to study the kinetics and predict thermal runaway of vinyl chloride (VC) suspension polymerization. Reactor temperature, monomer conversion, mole of initiator, radical concentrations in the two phases (i.e., VC-rich phase and PVC-rich phase), and average molecular properties were mapped during non-isothermal processes. Meanwhile, the risk of thermal runaway was evaluated using S–Z (divergence) and H–J criteria. Simulation results show that a lower jacket temperature T_j and a larger heat transfer coefficient U are able to postpone or even avoid the risk of thermal runaway. Both of the criteria serve well for the prediction of thermal runaway during non-isothermal processes. To prevent the occurrence of thermal runaway to the greatest extent, model-based design of strategies for an isothermal polymerization process was done. Specifically, either jacket temperature T_j or heat transfer coefficient U can be fine-tuned to maintain a 50°C isothermal process.