TO STUDY THE EFFECT OF VARIOUS CATALYST TYPES AND THEIR CONCENTRATION ON BIODIESEL PRODUCTION

Abstract

ABSTRACT Biodiesel is a low-emissions diesel substitute fuel made from renewable resources and waste lipid. The most common way to produce biodiesel is through transesterification, especially alkali-catalyzed transesterification. When the raw materials (oils or fats) have a high percentage of free fatty acids or water, the alkali catalyst will react with the free fatty acids to form soaps. The water can hydrolyze the triglycerides into diglycerides and form more free fatty acids. Both of the above reactions are undesirable and reduce the yield of the biodiesel product. In this situation, the acidic materials should be pretreated to inhibit the saponification reaction. Homogeneous basic catalyst like sodium hydroxide and potassium hydroxide are generally used for biodiesel production at industrial scale due to short reaction time and mild reaction conditions. However, the use of this catalyst leads to soap formation due to reaction of alkaline catalyst with free fatty acids. It is very difficult to remove catalytic species after reaction and to large extent formation of waste water streams. An alternative way to process vegetable oils, is the utilization of a solid state catalyst which will cope with the most economical and environmental draw back. The main hurdle for biodiesel preparation is the process economics which arises from the catalytic system. All these have been taken care by solid state catalyst. Currently, most of the biodiesel is produced from the edible/refined type oil using methanol and alkaline catalyst. However, large amount of non-edible type oils and fats are available in our country. In this study, crude neem oil is used as alternative fuel for biodiesel production. The difficulty with alkaline transesterification of these oils has contained large amounts of free fatty acids (FFA). These free fatty acids quickly react with the alkaline catalyst to produce soaps that inhibit the separation of the ester and glycerin. xiv A two-step transesterification process is developed to convert the high FFA oils to its mono-esters. Using 100 ml of oil, the optimum combination of parameters for pretreatment were found to be 0.45 v/v methanol-oil-ratio, 0.5% v/v H2SO4 acid catalyst, 50˚C and 45 min reaction time. After pretreatment of neem oil, transesterification reaction was carried out with 4.5:1 methanol-to-oil molar ratio, 1% KOH as alkaline catalyst, 75 min reaction time and 50˚C reaction temperature to produce the fatty acid methyl ester. This two step process gave maximum average yield of 70±2%.