HaNoi University of Mining and Geology
Faculty of Oil and Gas
Advanced Program
Topic: “Biodiesel”
Instructor: A.Prof. Pham Xuan Nui
Students: Vu Ngoc Hai
Ha Thanh Tung
Main contents:
Overview about Biodiesel
Process of Biodiesel Production
Catalyze for Biodiesel Production
Techniques for Biodiesel Production
Conclusion.
BIODIESEL
Biodiesel is an alternative fuel for diesel engines that is now receiving great attention world wide


Biodiesel is defined as the mono-alkyl esters of fatty acids derived from vegetable oils or animal fats.
BIODIESEL
Biodiesel is the product obtained when a vegetable oil or animal fat is chemically reacted with an alcohol to produce fatty acid alkyl esters.
Methanol
Ethanol
BIODIESEL
Feedstock for Producing of Biodiesel:
Virgin oil feedstock
Waste vegetable oil
Animal fat
Algae
Oil from halophytes
Sewage Sludge
There are 5 primary reasons for encouraging the development of biodiesel:
It provides a market for excess production of vegetable oils and animal fats.
It decreases the country`s dependence on imported petroleum.
Biodiesel is renewable and does not contribute to global warming due to its closed carbon cycle.
The exhaust emissions from biodiesel are lower than with regular diesel fuel.
Biodiesel has excellent lubricating properties.
Production of Biodiesel
Transesterification reaction
Catalysis for process of Biodiesel production
Catalyst for Biodiesel reaction
Homogeneous catalysts
Heterogeneous catalysts
Homogeneous acid-catalysts
Homogeneous base-catalysts
Heterogeneous acid-catalysts
Heterogeneous base-catalysts
Homogeneous base catalysts

Alkaline metal alkoxides: are most active catalysts, since they give very high yields in short reaction times even if they are applied at low molar concentrations
Alkaline metal hydroxides:are a good alternative since they can give the same high conversions of vegetable oils simply by increasing the catalyst concentration to 1 or 2 mol%
Heterogeneous acid catalysts
Ion-exchange resins: are widely used in important industrial processes for both separation and reaction applications.
Zeolites: are crystalline aluminum-silicates with a three-dimensional porous structure. They can be synthesized with different crystal structures, definitive pore sizes, framework Si/Al ratios and adjustable acid centers to have some important catalytic properties.
Heteropoly acids
Heterogeneous base catalysts
Hydrotalcites: are a class of an ionic and basic clays known as layered double hydroxides with the formula Mg6Al2(OH)16CO3.4H2O
Metal oxides: are composed of cations possessing Lewis acid and anions with Brønsted base.
Metalic salts: Inorganic solid bases, such as sodium silicate, vanadyl phosphate, calcium zincate and calcium methoxide, are low-cost and easy-to-use heterogeneous catalysts. Reports on metallic salts catalyzed conversion in biodiesel preparation are rare.
Supported base catalysts:Alkali metals (Li, Na, K) and alkaline earth metals (Mg, Ca, Ba) are the most common sources of super basicity, and selected as the active species of supported catalysts for biodiesel synthesis.
Transesterification Mechanism
The transesterification reaction involves catalytic reaction between triglyceride and alcohol such as methanol, ethanol, and propanol to form biodiesel (FAMEs) and glycerol. In the reaction, 3 reactions are required to complete the transesterification of a triglyceride molecule. In the presence of acid or base, a triglyceride molecule reacts with an alcohol molecule to produce a diglyceride and FAME. Then, a diglyceride reacts with alcohol to form a monoglyceride and FAME. Finally, an monoglyceride reacts with alcohol to form FAME and glycerol. Diglyceride and monoglyceride are the intermediates in this process.
Transesterification mechanism
Transesterification reactions of glycosides with alcohol.
Mechanism for heterogeneous acid-catalyzed transesterification

Acidic or basic functional groups in the active sites of solid catalysts catalyze the reaction by donating or accepting protons:
Firstly, triglycerides are protonated at the carbonyl group on the surface of solid acid.
Then, a nucleophilic attack of the alcohol to carbocation forms a tetrahedral intermediate (hemiacetal species). Unstable tetrahedral intermediate leads to proton migration, followed by breakdown of the tetrahedral intermediate with assistance of solvent.
After repeating twice, 3 new FAMEs as products were produced and the catalyst was regenerate.
Mechanism for heterogeneous acid-catalyzed transesterification
Mechanism for heterogeneous base-catalyzed transesterification

In base-catalyzed process, OH- or CH3O- ions performed as active species:
First, ion-exchange proceeded after methanol absorbed on the surface of solid base, producing catalytic active specie (CH3O-) which is strongly basic and highly catalytic active.
Secondly, nucleophilic attack of CH3O- on the carbonyl carbon of triglyceride formed a tetrahedral intermediate.
Thirdly, rearrangement of the intermediate resulted in the formation of FAME.
Finally, protons were converted to diglyceride ion to generate diglyceride. This sequence was then repeated twice to yield glycerol and biodiesel.
Mechanism for heterogeneous base-catalyzed transesterification
Techniques for Biodiesel Production
Techniques for Biodiesel Production
Conclusion
Biodiesel is the most promising fuel in the near future as an alternative to fossil diesel.
Homogeneous catalysis is a predominant method for transesterification reaction. But separating the catalyst from a mixture of reactants and product is difficult.
Compared with liquid acid catalysts, solid acid catalysts have distinct advantages in recycling, separation, and environmental friendliness.