Some researchers believe that when working with oils of high acidity, the best way is hydrolyze all TAG, DAG and MAG in FFA and glycerin. After this step, the FFA is esterified with alcohol would be of interest. In my view, is very difficult specify in acidity the biodiesel (FAME or FAEE) by this route and requires process of polishing.

"Biodiesel is a fuel that is obtained from a manufacturing process that converts plant oils or animal fats together with alcohol into a fuel that can be used in an internal combustion engine" (Office of Gas and Electricity Markets, 2009). Chemically it is the alkyl esters of fatty acids which are produced by trans-esterification of triglycerides of fatty acids using an alcohol, normally methanol or ethanol.

Bio-oil is a kind of liquid fuel made from biomass materials using pyrolysis or hydro-thermal treatments.The terms liquefaction, hydro-liquefaction and hydro-thermal liquefaction are used for processes where wet biomass is converted to bio-oil by temperature and pressure in the presence of a catalyst.

The algal lipids are mainly glycolipids, phospholipids, sulfolipids, small amount of triacylglycerols, chlorophyll and others. They have to be saponified and converted in methyl esters, or directly trans-esterified, before being used as biodiesel.

Regards!

Hydrolysis or transestirification (treatment with methanol or ethanol) of vegetable oil such as Jatropha Curcas is a process by which triglycerides (esters of long chain fatty acid with glycerol) are converted into methyl or ethyl esters of long chain fatty acids (Biodiesel) and glycerol. Hope this clears your doubt.

Biodiesel is mono- methyl ester of fatty acids. As it is known, fat/vegetable oil is triglyceride which is glycerol ester of fatty acids. For this reason, biodiesel production process is an trans -esterification process which is carried out by changing glycerol groups by methyl groups in the presence of sodium methoxide as catalyst so the glycerol is obtained as a side product in this process. This trans-esterification process is the real process which is used often in technology today. But, instead of this single step process, sometimes vegetable oil is hydrolyzed in first step by any way such as enzymatic hydrolysis or water vapor hydrolysis at high temperature and high pressure to the faty acids then free fatty acids are converted to biodiesel by the esterification reaction with methyl alcohol. But this way is not preferred in the technology generally.

Dear Sir, If you posted along with the reference, then it will be easy for you to get necessary answer.

Usually rate of hydrolysis will be measured when they are using lipase. But I have never seen biodiesel preparation by complete hydrolysis, since transesterfication is the combination of hydrolysis and esterification (by its product) using intermediate products between the reactions and also reversible.

Biodiesel is obtained from oil-rich crops such as rapeseed, sunflower, soybean and oil palm. The oil in such crops is largely made up of long-chain triacylglycerols (TAGs). Although unmodified vegetable oil can be used directly in diesel engines, it is far more efficient to convert the TAGs to their methyl ester derivatives.

This is achieved via the process of methanolysis. The vegetable oil is incubated with methanol at about 60°C in the presence of an alkaline catalyst such as sodium hydroxide or alkoxide. The result is the formation of methyl esters and glycerol.

Methyl esters can be used alone as a diesel fuel normally labelled as B100. More commonly, however, methyl esters are mixed with petroleum diesel to produce either 5% (B5) or 10% (B10) biodiesel blends. The leading producers of biodiesel are the European Union (mostly from rapeseed oil), USA and Brazil (both mostly from soybean oil).

Baskar - I am not quite sure what you are looking for as an outcome for your question.

Do you want to understand the chemistry of biodiesel manufacture and the issues with it's use and application. If so get the book Biodiesel, the comprehensive handbook by Martin Mittelbach. This is a very mature technology.

If you are looking for more advanced technologies and the best way to get a high quality jet/diesel fuel you should look to focus on looking for maximum carbon conversion to C9 to C25 and the removal of O,N and S in particular.

Hope that helps.

Biodiesel can be prepared from animal, plant or microbial fats and oils by,

1. Alkaline catalyzed transesterification (suitable for feedstock with low free fatty acid).

2. Acid catalyzed tranesterification/esterification (good for feedstock with high FFA).

3. Tranesterification double step process (good for feedstock with high FFA).

Alkaline metal hydroxides or methoxides are very effective catalysts for transesterification. The rate of alkaline catalyzed transesterification is about 4000 times faster than acid catalyzed transesterification. But its drawback is, FFA cannot be converted to ester. It is only neutralized to fatty soap, which further complicate the separation and cause an additional loss of biodiesel in the separation step.

Acid is a good catalyst for both esterification and transesterification. The rate of transesterification is very much slower than esterification. This is the reason why some researches chose the double step process for high FFA feedstock (esterification of FFA with acid catalyst followed by alkaline catalyzed trnsesterification). Total reaction times are still shorter than one step acid catalysis.

Theoretically, similar to the double step process, it is possible to hydrolyze triglyceride to FFA (or soap), follows by esterification to form biodiesel. Reaction time should be approximately the same as the esterification-transesterifcationreaction. However, the major drawback of this process is, very large amount of alkaline metal is required for hydrolysis. In the hydrolysis, the hydroxide acts as a reactant (not catalyst). So you can imagine that very large amount of acid to neutralize the soap is un-avoidable. And additional amount is required for esterification catalyst.

The purpose of hydrolysis process for biodiesel production from vegetable oils are :(1) corverting the triglyseride in vegetable oil using H2O molekul to produce (a) carboxylic acid and (b) glycerol; then after the glycerol is separated from the mixture, the process continued by ( 2) esterification of the carboxylic acid using alcohol (methanol or ethanol) to produce biodiesel (methyl/ethyl ester) and H2O.

Hope that helps.

Kanit Krisnangkura's answer is correct! But not speak about the hydrolysis.

The process is like as Supranto Supranto write. This process has a role in case of high FFA-containing feedstocks. In case of 30-60% FFA-content in the feed (eg.: fats from the protein industry produced from animal carrions and wastes from slaughterhouses) the traditional processes are not suitable.

It is possible to separate the FFAs from the feed by vacuum distillation, but it is very expensive. The 2 step process is very slow.

So it is a good idea to produce from the high FFA feed a 100% FFA intermediate. From the fatty acids it can be produced FAMEs, essential fatty acids, soaps.......

Implement glycrolysis esterification for low quailty Oil(Hi-FFA)