RUNAWAY REACTION IN THE EPOXYDATION OF VEGETABLE OIL

Chemical processes can undergo to thermal runaway if the rate of heat generation is faster than the rate of heat removal by cooling system, thus leading to a continuous rise in the reactor temperature and a consequent acceleration of the reactions, leading eventually to explosion. This phenomenon needs to be investigated in the chemistry of peroxides, in particular for epoxidation reactions, when the passage from lab-scale to industrial scale is under investigation. Among others, the epoxidation reaction of vegetable oil is particularly interesting for industrial use. Oil epoxidation is carried out by Prileshajew’s reaction, where the oil double bonds are reacted with organic peroxyacids (generally performic or peracetic) produced in situ in the reaction vessel by acid catalyzed oxidation of the corresponding organic acid with hydrogen peroxide. The reaction is highly exothermic (Hr ≈ 230 kJ/mol of double bond of the unsaturated substrate) and decomposition reactions are likely. The scope of this work is the safety analysis for the occurrence of the runway reactions in the epoxidation of soybean oil in a semi-continuous fed-batch reactor (the classical technology) [Santacesaria et al., 2011] and in a new continuous reactor configuration proposed in previous works [Kralisch et al, 2012; Santacesaria et al, 2012 ]. To this aim, the initial temperature in the reaction vessel and in the jacket and the operating conditions (flow rate of the mixture of hydrogen peroxide and formic acid) have been purposely varied and compared with the data produced by the existing thermo-kinetic model [Salzano et al., 2012]. Ultimately, results are addressed to the recognition of the optimum between maximum yield and safety operations for semi-batch and continuous reactors