Simpler, Cheaper Biodiesel From Waste Oil

Chemical engineers at Univesity of La Guna in Spain have developed a simpler and less expensive method of producing methyl ester biodiesel from waste oils and vegetable oil triglycerides. The process involves substituting an easily separable solid catalyst for harsh basic catalysts such as sodium hydroxide. Highly basic NaOH creates side reactions that decrease yield and force expensive and time consuming purification steps that would be unnecessary using the La Guna researchers' method. The production facilities could be simpler and less expensive, and the production time from feedstock to product would be reduced.

Biodiesel is a cleaner burning fuel than diesel and a suitable replacement. It is made from nontoxic, biodegradable, renewable resources, such as new and used cooking oil and animal fats. Fats and oils are chemically reacted with alcohols (transesterification reaction) to produce fatty acid methyl esters (biodiesel). Glycerine, used in the pharmaceutical and cosmetic industry along with many other applications, is produced in this reaction as a byproduct. The processes and production of biodiesel (methyl esters) from vegetable oil and animal fats feedstock remain a strong growth market in the European Union as well as the United States and Canada.
The most commonly used technology for fats and oils transesterification is based on the use of batch reactors, in which a basic homogeneous catalyst is used. The use of homogeneous catalysts requires extensive conditioning and purification steps for the reaction products (methyl esters and glycerol) to separate the catalysts. In contrast, heterogeneous catalysts are easily removed from the reaction mixture, making the purification step easier.(1) Biodiesel production costs could certainly be reduced by using a heterogeneous catalyst for transesterification reaction instead of a homogeneous catalyst. This heterogeneous process provides higher quality esters and glycerol, which are more easily separated and further expensive refining operations are not needed.(2) _ACS