菜籽油脚制备生物柴油的原料预处理研究

Pretreatment of rapeseed oil sediment used to prepare biodiesel

菜籽油脚浸提油酸值高、杂质多,不利于酯交换生产生物柴油,故采用四水硫酸锆为催化剂对浸提油进行甲酯化降酸处理。通过单因素试验和正交试验,确定最佳酯化降酸条件为:醇油摩尔比12∶1,催化剂加入量3%,反应时间3h,反应温度70℃。在最佳酯化条件下浸提油的酯化率达到98.55%,降酸油酸值(KOH)降为0.81mg/g,磷含量降为0.006%;四水硫酸锆的插层性能还能使浸提油中的磷脂、色素随胶体一起沉降下来,脱色率高达73.6%。将处理后的降酸油进行固体碱催化酯交换反应制备生物柴油,脂肪酸甲酯含量为91.8%。

Because of the high acid value and impurity, the rapeseed oil sediment is not suitable for producing biodiesel. The zirconium sulfate tetrahydrate was used as a solid acid catalyst in the methyl esterification reaction to reduce the acid value and improve the applicability in producing biodiesel. The optimal conditions of methyl esterification were as follows ： molar ratio of methanol to oil extracted with acetone from rapeseed oil sediment 12：1, amount of catalyst 3% , reaction time 3 h, reaction temperature 70 ℃. Under the conditions, the esterification yield was 98.55 % , and the acid value of the extracted oil reached 0.81 mgKOH/g, the content of phosphorus reduced to 0.006%. Phospholipids and pigment in the extracted oil could be sedimented with the colloid because of the intercalation of zirconium sulfate tetrahydrate and the decolouration rate was 73.6%. After deacidification, the oil was used to produce biodiesel catalyzed by solid alkali, and the content of fatty acid methyl ester was 91.8%.