Research On The Doping Modification Of Iron Oxide Catalyst In The Preparation Of Sebacic Acid By Cracking Castor Oil

Sebacic acid is an important chemical raw material, mainly prepared by catalytic cracking of castor oil. It can be used to produce high-quality engineering plastics, heat-resistant lubricants, cosmetics, additives and surfactants, etc. In order to solve the pollution problem of the lead oxide catalyst in the traditional preparation technology, our laboratory has been developed for the clean production technology of iron oxide as catalyst. However, the condition of the reaction temperature is relatively rigid, this article try to doping modification of iron oxide catalyst, and exploration the process of preparing sebacic acid by cracking of castor oil under the condition of low temperature.The effect of dopants and doping amount on catalytic properties of iron oxide was studied under low temperature conditions. The results show that catalyst has the highest catalytic activity in preparing sebacic acid by cracking of castor oil, when doped 6% magnesium ions. The optimal preparation condition of catalyst:the precursors were prepared by sol-gel method, and used ammonium hydroxide solution as precipitant, the precursors were calcined at 600? for 4 h.Catalysts were characterized by XRD, SEM, EDAX and TPR, and the precursors were characterized by DSC/TGA. The results showed that:the crystal type of catalysts is a-Fe2O3, was not change, and magnesium ions were evenly distributed in catalyst, after doped 6% magnesium ions. After doped 6% magnesium ions, made the particle size of catalyst smaller, the reduction temperature of catalyst be increased to 307? from 294 ?, and the stability of catalyst was improved in the system of preparation of sebacic acid by cracking castor oil. Moreover, the temperature of the formation of ?-Fe2O3 from the precursors be increased to 500?600? from 400?500?, after doped 6% magnesium ions.Research on the process of preparing sebacic acid by cracking of castor oil under the condition of low temperature, used the catalyst after doping modification, and the reaction temperature was 250 ?. The results showed that:the dosage of castor oil is 15 mL, the optimum dosage of catalyst is 0.3 g, the optimum dosage of the mass fraction of 40% NaOH solution is 15 mL, the optimum dosage of liquid paraffin is 50 mL, under the condition of 250 ?. And with the unmodified iron oxide as catalyst was compared, the optimum time of reaction be reduced to 4.5 h from 5.0 h, the yield of sebacic acid be increased to 39.64% from 25.24%.To calculate kinetic data in the reaction of preparing sebacic acid by cracking of castor oil, and comparison the effect of the catalyst after doping modification and the unmodified catalyst on the kinetics constants of the cleavage reaction. The results showed that:at the temperature of reaction were 250?,260 ? and 270 ?, compared with the catalyst without doping modification, the catalyst, after doping modification, respectively made the rate constant be raised to 0.7800 h-1,0.8276 h-1,0.8955 h-1 from 0.7180 h-1,0.8020 h-1, 0.8864 h-1, and apparent activation energy be reduced to 16.235 kJ/mol from 24.893 kJ/mol. It is shows that the activity of iron oxide catalyst can be improved after doping modification, improve the cracking reaction rate, reduce the apparent activation energy of the cracking reaction, and made the reaction of preparing sebacic acid by cracking of castor oil under the condition of low temperature more easily.