Biodiesel fuel production by transesterification of oils.

https://seniordesign.engr.uidaho.edu/2007_2008/frenchfryfuel/Biodiesel%20from%20WVO%20Part%201.pdf

Biodiesel production from waste cooking oil: 1. Process design and technological assessment

Integrated biodiesel production: a comparison of different homogeneous catalysts systems.

Biodiesel (fatty acid methyl ester) is a nontoxic and biodegradable alternative fuel that is obtained from renewable sources. A major hurdle in the commercialization of biodiesel from virgin oil, in comparison to petroleum-based diesel fuel, is its cost of manufacturing, primarily the raw material cost. Used cooking oil is one of the economical sources for biodiesel production. However, the products formed during frying, such as free fatty acid and some polymerized triglycerides, can affect the transesterification reaction and the biodiesel properties. Apart from this phenomenon, the biodiesel obtained from waste cooking oil gives better engine performance and less emissions when tested on commercial diesel engines. The present paper attempts to review methods for the transesterification of waste cooking oil and the performance of biodiesel obtained from waste cooking oil in a commercial diesel engine. The paper also examines the basic chemistry involved during frying and the effects of the products formed in the frying process on biodiesel quality.

Waste cooking oil – an economical source for biodiesel: a review

Vegetable oils and animal fats can be transesterified to biodiesel for use as an alternative diesel fuel.
Conversion of low cost feedstocks such as used frying oils is complicated if the oils contain large amounts of free fatty
acids that will form soaps with alkaline catalysts. The soaps can prevent separation of the biodiesel from the glycerin
fraction. Alternative processes are available that use an acid catalyst. The objective of this study was to investigate the
effect of process variables on acid-catalyzed transesterification. The molar ratio of alcohol, reaction temperature, catalyst
amount, reaction time, water content, and free fatty acids were investigated to determine the best strategy for producing
biodiesel. Food grade soybean oil was used to prepare esters using excess methanol and sulfuric acid as a catalyst. To
compare the effect of different alcohol types on ester formation, methanol, ethanol, 2-propanol, and n-butanol were
compared. The American Oil Chemists’ Society Method Ca 14-56 was used to measure the biodiesel’s total glycerin
amount as an indicator of the completeness of the reaction. It was found that acid catalysis can provide high conversion
rates but much longer times are required than for alkaline catalysts. The acid catalyst also requires the concentration of
water to be less than 0.5%, which is about the same as is required for alkaline catalysts. Water formed by the
esterification of free fatty acids limited their presence in the oil to 5%.

Biodiesel production via acid catalysis

Used frying oil was transesterified by reaction with excess alcohol under both acidic and basic conditions. The alcohols used were: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-ethoxyethanol. Yields of the fuels determined by gas chromatography and their viscosities are reported. The best result was obtained using methanol with catalysis by potassium hydroxide. The methyl ethyl and 1-butyl esters all ran very well in short-term engine tests with a laboratory high-speed diesel engine.

W. Deshpande

Papers

Conversion of used frying oil to diesel fuel by transesterification: preliminary tests