Study On The Process And Kinetics For Dehydrogenation Of Vapor Phase Methyl Isobutyl Carbinol To Methyl Isobutyl Ketone

Methyl isobytyl ketone(MIBK) is one of the most important chemical products, which is widely used in the field of chemical engineering especially in the production of antioxidant. This paper concerned with the preparation of a kind of catalyst containing Cu and initiated its application to the dehydrogenation process of vapor phase methyl isobutyl carbinol(MIBC) to produce methyl isobutyl ketone(MIBK). The factors influencing the conversion of MIBC and the selectivity for MIBK were discussed, which provided a new method for fixed-bed recycling MIBC and reducing the cost in the synthesizing process of rubber antioxidant N-(l,3-Dimethyl butyl)-N'-Phenyl-p-Diamino Benzene(4020), in which the byproduct MIBC was obtained partly from the hydrogenation of MIBK under high pressure.The experimental study of vapor phase methyl isobutyl carbinol dehydrogenation to produce methyl isobutyl ketone using a CuO-ZnO-Al₂O₃ catalyst prepared by a co-precipitation method was carried out under the atmospheric pressure. By a single-tube reactor, the influences of the reaction temperature and the space velocity of methyl isobutyl carbinol on the dehydrogenation activities were experimentally determined. The experimental results showed that under the temperature of 483-513K and space velocity of 1.0².0 h^-1, the maximum per pass conversion rate of methyl isobutyl carbinol was 91.11%, and the selectivity for methyl isobutyl ketone was over 99.0%. The research also concerned the stability of catalyst, the results showed that the catalyst had a stable conversion and kept the selectivity under the experimental conditions.Detected by a Gas Chromatography-Mass Spectrography method, the main byproduct was found to be a dimer of MIBK(C₁₂H₂₄O) rather than alkene, for which the the mechanism was assumed.Based on these experimental results, the Langmuir-Hinshelwood model and the Power velocity model were adopted respectively to figure the reaction. The L-H model showed that the adsorption of MIBC was rate-determining step and the apparent activation energy E_a was equal to 76.89 kJ · mol^-1, the adsorption enthalpy of MIBK was -8.17 kJ·mol^-1 An experiential rate equation has been determined by a leastsquare method as ,in which the apparent activation energyE_a was equal to 69.01 kJ · mol^-1.The analytical results of the two equations by the correlation index and variance error calculations indicate that the calculated conversion data agree well with the experimental data. Compared to L-H model, the Power velocity model show a better possibility for the practical application.