Thermolysis of benzyl phenyl ether in subcritical and supercritical water, and supercritical methanol

The thermolysis of benzyl phenyl ether (BPE) in subcritical and supercritical (SC) water and SC methanol has been studied to investigate the solvent effects on thermolysis of ether compounds in supercritical fluids (SCFs). Experiments were performed at temperatures of 593 and 648 K, over a solvent density range from 2.2 to 21.7 mol/dm³, and in the range of reaction period from 180 to 2400 seconds. Reactions in water at 593 K proceeded under subcritical conditions, while all other reactions proceeded under SC conditions. Selectivity for reaction products was determined from the plot of product yield versus BPE conversion. It was found that both pyrolysis and hydrolysis occurred in subcritical and SC water, but only pyrolysis occurred in SC methanol. The lumped elementary reaction model for the reaction in SC methanol proposed by Wu et al. was extended to the reaction in subcritical and SC water by adding therefore hydrolysis reaction. The values of rate constants for such reactions as C-O bond fission, hydrogen abstraction, radical recombination, and hydrolysis were optimized using the multivariable constrained search method. The dependence of rate constants of BPE thermolysis in SCFs on density was discussed.