Study Of Preparating C_16～22 Higher Fatty Alcohol By Natural Oil

In order to obtain new agricultural preservation materials OHAA, we used the C16～22 higher fatty alcohol as raw material, which was prepared by natural oils. This paper used palm oil and rapeseed oil as raw material, studied on the transesterification process conditions, the mixed ester separation, enrichment C16-22 fatty acid methyl ester, methyl ester following the raw material handling pressure hydrogenation process conditions and alcohol products, physical and chemical properties of a preliminary exploration.Results were mainly showed as follows:As to analyzing some of the common physical and chemical properties of natural plant and animal oils and fatty acid composition, palm oil and rapeseed oil was selected as raw materials for the preparation of higher fatty alcohol C16-22, because the composition of fatty acids in palm oil was mainly C16 and C18 fatty acids, and fatty acid composition of rapeseed oil concentrated in the fatty acid C16-22.To optimize the reaction conditions in which palm oil and rapeseed oil were turned into fatty acid methyl ester, single factor experiments were designed and completed. The optimum reaction conditions were:methanol to oil molar ratio 6:1; catalyst amount of 1%; reaction temperature 65℃; reaction time 60min. The first transesterification reaction of rapeseed oil was higher (98%) under these conditions, while the methyl ester obtained from palm oil by transesterification reaction once was less than ideal, and saponification phenomenon was often emerged during the transesterification process. The second transesterification was implemented to increase the yield of palm oil methyl ester by orthogonal experiment. The optimum second methyl transfer process conditions were maintaining the temperature of 65℃, stirring speed 100r/min, the molar ratio of first ester of methanol to oil 3.5:1, the amount of catalyst 0.6%, reaction time 10min, the second esterification of methanol to oil ratio of 2:1, the catalyst 0.3%, reaction time 25min, not only to palm oil the yield of methyl to 98% or more, and reduce the amount of raw materials and the reaction time of methanol. Comparison of three transesterification, the yield of the methyl ester was lowest and the saponification was serious when transesterification reached three times.Urea was used to separate and enrich methyl ester compounds in palm oil and rapeseed oil. The effect of separation and enrichment of palm oil methyl ester compounds using urea by Box-Behnken response surface orthogonal design was studied, the results showed that the best process conditions were urea of 35 g,95% ethanol of 120 mL, inclusion temperature of 5℃, inclusion time of 16 h. At the same time, a comparative study of separation and enrichment of rapeseed oil methyl ester compounds by urea and molecular distillation carried out, the results showed the separation and enrichment of C22 fatty acid methyl ester by urea bag was better than distillation under laboratory conditions. The isolated products were researched by gas analysis, The results suggested the content of single carbon-chain methyl was higher among all components after separation, the content of C16 and C18 and C22 methyl ester was about 80%,94%,70% respectively.The single carbon-chain methyl ester components of high content which were obtained as above were processed by the pressure hydrogenation in the autoclave. Various process conditions of carbon chain methyl ester hydrogenation were obtained, and mixed carbon chain ester hydrogenation conditions are compared by single factor test, the results showed that the yield of higher fatty alcohol can reach 90% and the yield of fatty alcohol for methyl ester in the mixed carbon chain after hydrogenation was about 80%, when the temperature was 260℃～270℃, pressure was 10 MPa, time was 4-5 h, stirring speed was 900 r/min. By analyzing higher fatty alcohol products with GC-MS, it can be found that single carbon chain methyl ester of high content after hydrogenation was better than higher fatty alcohol products, In which the content of C16 fatty alcohol was 72.8% by the way of C16 fatty acid methyl ester hydrogenation, the content of C18 fatty alcohol was 94.1% by the way of C18 fatty acid methyl ester hydrogenation, the content of C22 fatty alcohol was 65.8% by the way of C22 fatty acid methyl ester hydrogenation. Besides, the content of C16～22 fatty alcohol was above 95% in higher fatty alcohol, which has reached the first standard of fatty alcohol.