Studies on Biodiesel Production

Abstract

Biodiesel is a nontoxic, biodegradable, renewable diesel fuel obtained from vegetable oils and fats. Biodiesel plays an important role in meeting future fuel requirements in view of its ability to reduce emissions from diesel engines for many air pollutant precursors, the lower toxicity of the diesel particulate matter emissions, and its edge over conventional diesel as they are obtained from renewable sources. The most common production process for biodiesel is through the batch transesterification of vegetable oils with alcohol. The main objective of this study to investigate safe and fast method, without using reflux, to produce biodiesel from Jatropha oil, considering the Indian perspective. Different transesterification reaction methods like homogeneous alkali and acid catalyzed method, heterogeneous solid catalyzed method, lipase, ultrasound-assisted and microwave assisted syntheses, employed in the study and best results are compared. It was observed that among all the methods employed in this study, except ultrasound-assisted and microwave-assisted syntheses methods, all the methods are giving not much comparable results and also required reflux to accomplish the reaction. That was not fulfilling the purpose of the study. Ultrasound-assisted and microwave-assisted transesterification of Jatropha oil gives good results. Present work studied influence of various process parameters i.e. reaction time, reaction temperature, oil to methanol molar ratio, amount of catalyst concentration was studied for all the methods. Analysis of biodiesel produced by each method employed in present study was carried out.

Considerable increase in conversion of triglyceride was obtained in a remarkably short time span of 45 min for 30 0C, 40 min for 40 0C and 30 min for 50 0C at conditions of molar ratio of oil to methanol of 1:9 with NaOH concentration of 1 wt% of oil using ultrasound-assisted synthesis. According to the kinetic study of ultrasound-assisted transesterification, the order of reaction is one and the activation energy required for reaction is 4094.61 cal/ mol.

Microwave-assisted technique was studied in three different ways: (1) Full microwave assisted synthesis without H2SO4 and without reflux. (2) Full microwave-assisted synthesis with H2SO4 and without reflux. Results and reaction conditions are not meeting with the objective of the study. New technique (Part microwave without reflux, PMWWR) was employed using microwave-assisted synthesis wherein part process accomplished under microwave irradiation and part outside microwave. Results are very much comparable to other published results using microwave irradiation with reflux. Maximum conversion of 93% was achieved at the reaction time 3 min, catalyst (NaOH) amount of 1% by wt. of oil and microwave output power of 600 W and 92% conversion was achieved at the reaction time 7 min, catalyst (NaOH) amount of 1% by wt. of oil and microwave output power of 300 W using Part microwave assisted synthesis without reflux and H2SO4 (PMWWR).

Biodiesel produced using well established homogeneous alkali catalyzed method and recommended method PMWWR was tested on four stroke diesel engine to test emission performance and engine performance.

PMWWR is the new, innovative, original and recommended method for further work. Also, ultrasound assisted synthesis has the potential of commercialization and can be recommended for further research. Economic analysis is to be done for recommended methods.