科研之友
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摘要
Epoxidation of canola oil was carried out using a peroxyacid generated in situ from hydrogen peroxide and a carboxylic acid (acetic or formic acid) in the presence of liquid inorganic acid, H(2)SO(4), as catalyst. Acetic acid was found to be a better oxygen carrier than formic acid as it gave about 11% more conversion of ethylenic unsaturation to oxirane than that given by formic acid under otherwise identical conditions. A high temperature of above 65 degrees C is significantly unfavourable for achieving high oxirane numbers, as the selectivity to oxirane ring opening reaction increases. Higher concentrations (above 0.5 mol/mol of ethylenic unsaturation) of acetic acid, formic acid or hydrogen peroxide are also detrimental (mainly, the carboxylic acids) but much less than that of the temperature effect. From a detailed process developmental study, the parameters optimised were a temperature of 65 degrees C, acetic acid-to-ethylenic unsaturation molar ratio of 0.5, hydrogen peroxide-to-ethylenic unsaturation molar ratio of 1.5 and sulphuric acid loading of 2%. A relative conversion to oxirane of 81% and an iodine value conversion of 86.5% were obtained under the optimum reaction conditions. The formation of the epoxide as well as ring-opened product of canola was confirmed by FTIR and (1)H NMR spectral analysis. From a kinetic analysis, the activation energy of this commercially important reaction was determined to be 10.7 kcal/mol. The findings of this study show that hydroxylated canola oil can be used as a starting material for the lubricant formulations.
- 出版日期2011-3
