Safety of ethoxylation reactions

摘要

Ethylene Oxide (EO) is a reactive monomer obtained by oxidation of ethylene. In ethoxylation processes, EO is reacted with various chemicals such as alcohols, phenols, acids, fatty alcohols and fatty acids, ammonia, amines, mercaptans, to produce a wide range of surfactants, solvents and specialty chemicals. Ethoxylation processes operate at temperatures between 40℃ and 200℃ under pressures ranging from atmospheric to 100 bar, mostly in the presence of a catalyst. The reaction of EO is exothermic. In continuous processes, a tube reactor or a series of stirred reactors or a combination of these, are used to produce solvents or commodities. Semi-batch ethoxylation processes are carried out in stirred reactors or in different types of loop-reactors to produce long chain ethoxylates. Liquid EO is injected in the process and dissolves in the liquid reaction mixture where the ethoxylation reaction takes place. A partial pressure of EO is also present in the gas phase if any. Due to the many accidents that have occurred in processing EO, related with its dangerous properties, the process design and operating conditions of ethoxylation processes may create important safety issues. In this paper, the standards in this field are discussed on the basis of: 1. the case histories collected from the literature, 2. the data available on interaction of EO with construction materials and gaskets, 3. the data on gas phase instability, limiting nitrogen concentration, MIE, explosion overpressure and the methods to control gas phase explosion hazard. 4. the literature on EO accumulation, runaway reaction hazard in ethoxylation processes and how to control it. A full review of the literature in this field is given.