tailieunhanh - Handbook of plant based biofuels - Chapter 4

4 Production of Biofuels with Special Emphasis on Biodiesel Ayhan Demirbas contents Abstract 45 Introduction 45 Vegetable Oils as Diesel Fuels .46 Biodiesel . 47 Noncatalytic Transesterification with Supercritical Alcohol Transesterification . 49 Transesterification Reaction Mechanism of Vegetable Oil 50 Variables Affecting Methyl Ester Yield . 51 Comparison of Fuel Properties andCombustion. | 4 Production of Biofuels with Special Emphasis on Biodiesel Ayhan Demirbas CONTENTS Vegetable Oils as Diesel Noncatalytic Transesterification with Supercritical Alcohol Transesterification Reaction Mechanism of Vegetable Variables Affecting Methyl Ester Comparison of Fuel Properties andCombustion Characteristics of Methyl and Ethyl Alcohols and Their Biodiesel Conclusions and Future Perspectives . 53 References. 53 ABSTRACT Biodiesel an alternative biodegradable diesel fuel is a renewable fuel that can be produced from vegetable oils animal fats and used cooking oil including triglycerides. It is derived from triglycerides by transesterification with methanol and ethanol. Concerns about the depletion of diesel fuel reserves and the pollution caused by the continuously increasing energy demands make biodiesel an attractive alternative motor fuel for compression ignition engines. There are four different ways of modifying vegetable oils and fats to use them as diesel fuel such as pyrolysis cracking dilution with hydrocarbons blending emulsification and transesterification. The most commonly used process is the transesterification of vegetable oils and animal fats. INTRODUCTION The term biofuel generally refers to liquid or gaseous fuels for the transport sector that are predominantly produced from biomass. Biomass all plants and living organisms can be converted into liquid and gaseous fuels through thermochemical 45 2009 by Taylor Francis Group LLC 46 Handbook of Plant-Based Biofuels and biological routes. Biofuel is a nonpolluting locally available accessible sustainable and reliable fuel obtained from renewable sources. The liquid biofuels being considered the world-over fall into the following categories 1 vegetable oils and biodiesels 2 alcohols and 3 biocrude and synthetic oils Demirbas 2006 . Figure shows the