Study On Macrokinetics Of Ethylen Epoxidation Over YS-7Silver Catalyst

The macrokinetic experiments of ethylene epoxidation over Ag-based catalyst, YS-7, were carried out using an internal-recycle gradientless reactor made by American Autoclave Engineers group under the conditions of pressure at2.1MPa, temperature from190℃to250℃, concentration of C2H4from14.00%to31.00%, O2from3.00%to8.00%, CO2from3.00%to10.00%and concentration of ethylene dichloride (EDC) inhibitor, from0.10ppm to0.50ppm. Based on the kinetic models as reported in literatures, sixteen kinds of semi-empirical and semi-theoretical macro-kinetic models (either the hyperbola type or the power law type) were developed. The residual squares sum among the experimental data and simulation data was taken as the target function. By means of Levenberg-Marquardt optimal methods, the parameters of the kinetic models were estimated, respectively, and eight kinds of macrokinetic models of YS-7Ag-based catalyst were developed. Statistical test showed all these eight kinds of macrokinetic models were highly acceptable and reliable. It’s impossible that a catalytic reaction process can be described equivalently and effectively by the kinetic models which have obvious textural-difference. Thus, eight kinds of macrokinetic models mentioned above were distinguished with the industrial operating data. There were considerable differences in performance prediction among different models when they were employed to model three set industrial reactors. On the basis of comprehensive analysis, the macrokinetic model for YS-7Ag-based catalyst was determined finally, which had a very well simulation agreement with the industrial operating data. Its expression was written as follows:1denotes the main reaction of generating ethylene oxide;2denotes the side reaction of generating water and carbon dioxide.