PROCESS TO PRODUCE BIODIESEL FUEL USING SOLID CATALYST TO DECREASE THE EMISSION

植物油或动物脂肪与乙醇通过酯交换反应生成的脂肪酸烷基酯被称为生物柴油（BDF），用作柴油的替代品。通常甲醇被用作醇，然后生产的BDF是甲酯形式。溶解在甲醇中的氢氧化钠或氢氧化钾在工业上用作均相催化剂。然而，均相催化剂引起一些问题。由于这些碱性催化剂溶解在副产物甘油中，因此在分离后难以处理该副产物。使用非均相催化剂的方法将是简单的，并且催化剂容易与产物分离。因此，将简化所产生的甘油的纯化过程。此外，固体催化剂将重复或连续地用于反应。在本研究中，由于氧化钙并不昂贵，我们研究了氧化钙的催化活性。即使当使用粉状氧化钙时，该催化剂的活性也远低于均相催化剂如氢氧化钾的活性。我们还测试了负载在多孔氧化铝上的氧化钙催化剂。当30 g植物油和10 g甲醇与0.8 g活性最高的氧化钙在60 ℃下反应2 h后，转化率达到90%。催化剂的活性随反应重复次数的增加而降低。使用后的煅烧和甲醇洗涤不能防止失活。在本研究中，我们还没有确定这种失活的主要原因。然而，提高氧化钙催化剂的性能对于工业应用是重要的。

Fatty acid alkyl esters produced by the transesterification from vegetable oils or animal fats with alcohol is called as biodiesel fuel(BDF) and used as a substitute for diesel fuel. Usually methanol has been used as alcohol and then produced BDF is methyl ester form. Sodium hydroxide or potassium hydroxide dissolved in methanol is industrially used as homogeneous catalysts. However, homogeneous catalysts cause some problems. Since these basic catalysts are dissolved in the by-product ; glycerol, it is difficult to treat this by-product after the separation. The process using heterogeneous catalysts would be simple and the catalysts are easily separated from the products. Therefore, the purification process of yielded glycerol will be simplified. In addition, the solid catalysts would be used for the reaction repeatedly or successively. In this study, since calcium oxide is not expensive, we investigated the catalytic activity of calcium oxide. Even when the powdery calcium oxide was used, the activity of this catalyst was much lower than that of the homogeneous catalysts such as potassium hydroxide. We also tested the calcium oxide catalysts supported on porous alumina. The conversion reached 90 % after 2 h, when 30 g of vegetable oil and 10 g of methanol were reacted with 0.8 g of the highest active calcium oxide at 60 ℃. The activity of the catalyst decreased with the repetition of the reaction. The deactivation could not be prevented by the calcinations and methanol washing after the use. In the present study, we have not identified the main cause of this deactivation. However, it is important to improve the performance of calcium oxide catalyst for industrial use.