Jacobson synthesized and utilized various solid acid catalysts such as MoO3/SiO2, MoO3/ZrO2, WO3/SiO2, WO3/SiO2–Al2O3, zinc stearate supported on silica, zinc ethanoate supported on silica and 12-tungstophosphoric acid (TPA) supported on zirconia. They were synthesized and evaluated for biodiesel preparation from waste cooking oil containing 15 wt.% FFA. The results revealed that the zinc stearate immobilized on silica gel (ZS/Si) was the most effective catalyst in simultaneously catalyzing the transesterification of triglycerides and esterification of FFA present in waste cooking oil to methyl esters. The maximum FAME yield of 98 wt.% was obtained at the optimal parameters: molar ratio of methanol to oil of 18:1; catalyst amount of 3 wt.%; stirring speed of 600 rpm and reaction temperature of 200 °C with the most active ZS/Si catalyst. Particularly, the catalyst was recycled and reused many times without any loss in activity .
Another process, a plasma technology is promising for biodiesel synthesis from vegetable oils due to very short reaction time, no soap formation and no glycerol as a by-product.
Synthesis of biodiesel via acid catalysis.
Since a low frequency of ultrasound gives a high mixing efficiency, the frequency adapted for biodiesel production is in the range from 20 to 40 kHz. Many researchers have studied the production of biodiesel in a laboratory scale using an ultrasonic water bath with frequency of 24, 28 and 40 kHz [,,,,].
Experiment 11: Synthesis of Biodiesel and Soap ..
For instance, Di-Serio and co-workers have reported the use of carboxylic salts of metals such as Cd, Mn, Pb and Zn for the production of biodiesel from vegetable oil containing high amounts of FFA .
Flow esterification for the synthesis of biodiesel fuel ..
Despite the successful use of these catalysts, their application to biodiesel manufacturing is restricted due to their cost and delicate conditions of synthesis.
Kinetics of biodiesel synthesis from sunflower oil ..
NMR analysis demonstrated that AlCl 3 catalyzes both the esterification of long chain fatty acid and the transesterification of vegetable oil with methanol suggesting that the catalyst is suitable for the preparation of biodiesel from vegetable oil containing high amounts of free fatty acids.
fatty acid and cholesterol synthesis and on acetate ..
Biodiesel is a renewable and alternative fuel to petro diesel fuel. In addition, biodiesel is environmental friendly due to its easy biodegradability, non-toxicity, being primarily free of sulfur and aromatics and containing oxygen in its structure resulting in production of more tolerable exhaust gas emissions than conventional fossil diesel, despite providing similar levels of fuel efficiency. Currently, biodiesel is produced thank to esterification and transesterification reactions from edible and non-edible vegetable oils or animal fats with primary alcohols in the presence of an acid- or base-catalyst. Several catalysts such as homogeneous acid/base, heterogeneous acid/base, enzymes, have been studied and applied to the synthesis of biodiesel. However, in commercial production, a homogeneous alkaline catalyst transesterification is predominately used for good quality oils containing a low content of FFA because the base alkaline catalyst gives a high FAME yield in a short reaction time and the reaction can be carried out in simple equipment. In contrast, with poor quality raw oils containing a high amount of FFA, a strong sulfuric acid catalyst esterification used as a pre-treatment step followed by an alkaline catalyst transesterification is the most popular way to produce biodiesel.
Ester synthesis by esterification - Organic chemistry
Biodiesel can be synthesized by the transesterification reaction of a triglyceride with a primary alcohol in the presence of catalysts. Among primary alcohols, methanol is favored for the transesterification due to its high reactivity (the shortest alkyl chain and most polar alcohol) and the least expensive alcohol, except in some countries. In Brazil, for example, where ethanol is cheaper, ethyl esters are used as fuel. Furthermore, methanol has a low boiling point, thus excess methanol from the glycerol phase is easily recovered after phase separation .