生質柴油之非勻相催化劑

Abstract

生質柴油又稱生物柴油，是以未加工過或者使用過之植物油或動物脂肪作為原料，採用混合稀釋、微細乳化、熱解或轉酯化反應等方法所產製之生質燃料，具生物可分解性、無毒、燃燒後污染性低等優點，不僅可以單獨使用，也可與石化柴油混合使用，是一項具有潛力之潔淨替代燃料。 轉酯化反應是指以適當比例混合之油脂與醇類，在加入與反應物同相之酸性催化劑、鹼性催化劑、脂解

Biodiesel is a kind of clean and renewable energy which can be used directly or mixed with fossil diesel as fuel on vehicles. It can be extracted from recycled vegetable oil or animal fat by using blending, diluting, microemulsion, pyrolysis, or transesterification method. Transesterification means that appropriate amount of alcohols and fat are mixed in supercritical condition with various kind of catalyst to produce esters. It is a common process in producing biodiesel. By using all kinds of catalyst, heterogeneous catalyst is relatively environment-friendly and makes a simple process. In this study, soy bean oil is mixed with methanol under 60℃ with sodium hydroxide as catalyst to investigate the effect of molar ratio between oil and methanol and catalyst amount. Hydrotalcite, one kind of homogeneous catalyst, is then produced at different temperature by 3:1 Al/Mg molar ratio after the best ratio between oil and methanol is determined. Sodium hydroxide is then replaced by hydrotalcite to examine the performance of hydrotalcite as catalyst. As result, the best ratio between oil and methanol is 6:1 with Sodium hydroxide as catalyst. Conversion ratio and reaction rate are both improved with increasing catalyst amount. In preparation of hydrotalcite, crystallization dimension is reduced at higher calcination temperature which makes a larger accessible area. The content of Alumium oxide is decreasing with increasing magnesium oxude. Alumium oxide is all replaced by MgAl2O4 when calcination temperature is rised to 650℃. Hydrotalcite made at 550℃ has the best result in conversion ratio and conversion ratio does not rise significantly with increasing catalyst amount in long term reaction time. However, the initial reaction rate is clearly related to the catalyst amount.