| The sebacic acid is a kind of broad-spectrumsed chemical materials, its demand is increasing rapidly in recent years, especially the high quality sebacic acid. The traditional production process of sebacic acid is using phenol as diluent, and conducting alkaline cracking of castor oil in the condition of high temperature, but this process not only has serious pollution to environment, whose yield is low, but also the products hidden safety problems. This paper targeted the development of cleaning process getting sebacic acid from castor oil, study on the preparation, characterization and application technology of ferric oxide supported by activated carbon (Fe2O3/AC) catalyst of catalytic alkaline cracking process.Fe2O3/AC catalyst is prepared by impregnation and precipitation method. First of all, improve the loading Fe3+ amount of carrier activated carbon and the adsorption force through pretreatment. Conduct the acid, oxidation or ultrasonic pretreatment to the selected coal, coconut shell, nut shell and wood activated carbon, and compare the effects of acid type and concentration, treatment time, the oxidizing agent type and concentration, ultrasound on the pretreatment. Coal activated carbon pretreated by the method of being treated by 30% nitric acid in ultrasonic environment for 1 hours after washing, owns the best adopting iron amount. EDTA titration shows that the adopting Fe3+ amount of the coal activated carbon after pretreatment increases from 10.46 mg/g to 36.24 mg/g; Boehm titration shows that the total content of surface oxygen groups increases from 0.432 mmol/g to 0.721 mmol/g; FTIR test shows that the characteristic absorption strength of the surface functional group of phenolic hydroxyl and carboxyl increases with oxidation strength; but the characterization of FE-SEM shows that after pretreatment the surface hole structure of coal activated carbon is improved with the reduction of ash.Then, on the basic of carrier pretreatment, Fe2O3/VAC catalyst is prepared by impregnation and precipitation method, study the affect on catalyst activity of the main factors during preparation process from the three main processes of impregnation, precipitation and roasting. Obtain the optimum preparation conditions of the catalysts:the iron content loaded is 12%, the mpregnating solution is the solution of 0.6 mol/L Fe(NO3)3, the precipitating agent is the solution of 0.5 mol/L Na2CO3, and the calcination temperature and time is 350℃ and 3 h. Under these conditions preparing Fe2O3/AC catalyst, its iron content is 28.72 mg/g, when used for catalytic cracking reaction of castor oil, the yield of products sebacic acid is 68.2%, The activity of catalyst is 0.0114 mol/(h-g). TG/DTG test shows that the early somatic Fe(OH)3 has a completely thermal decomposition at the roasting temperature; XRD test shows the catalyst owns a-Fe2O3 crystal characteristics; ED AX test show that the surface elements are mainly C, O, Fe, and combined with SEM and ED AX test shows that the catalyst surface morphology and elemental composition had no significant changes in the reaction process, which shows that C-O-Fe or COO-Fe binding plays an important role in maintaining the stability of the catalyst. Stability test of the catalyst indicated that after used 3 times, the iron content of catalyst, the sebacic acid yield and the activity of catalyst is reduced to 87.8% of the catalyst before repeating, which shows the stability of the catalyst is good.Finally, using the prepared Fe2O3/AC catalysts, study the change of the reaction conditions of catalytic cracking reaction of castor oil. Get the best process condition after enlarging experiments:the amount of catalyst is 5% of the mass of ricinoleic acid, the volume ratio of diluents and ricinoleic acid is 5:1, the reaction temperature is 270℃, the reaction time is 3 h. Under these conditions, the yield of sebacic acid was 68.6%, the iron content of product was 80.2μg/g. The prepared catalyst showed better catalytic activity under the optimum reaction conditions. |
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