Modification of vegetable oils. VII. Alkali catalyzed interesterification of peanut oil with ethanol

Abstract

T H E alkali-catalyzed displacement of the glycerol in a fat b y methanol or ethanol is a n import a n t reaction in fat and oil technology. Besides producing monoesters f o r use as such, the reaction simplifies the manufacture of some soaps, especially anhydrous soaps (2, 3); a n d it is valuable in conjunction with processes f o r fraetionating fatty acids. Potentially the reaction is important in producing mono-a n d diglyeerides of unsaturated acids, and it presents interesting possibilities in the field o f "tailor-made" f a t s .In a typical large-scale operation alcoholysis (the type of interesterification u n d e r discussion) is carried out in a n open kettle b y mixing substantially n e u t r a l fat with approximately 1.6 equivalents of anhydrous methanol or ethanol in which has been dissolved a fraction of 1% (on a n oil basis) o f sodium o r potassium hydroxide. Mixing is discontinued when the solutions become homogeneous. A f t e r standing a n hour or two a t 80°C. the free glycerol which has separated and settled to the b o t t o m of the t a n k is withdrawn, and the monoesters are purified by washing with water. The alcoholysis reaction as described above has been discussed in several publications; however, a n u m b e r of interesting questions have been left unanswered, and some of the conclusions reported are a t variance with those reached by the present authors. Toyama a n d co-workers (10) f o u n d t h a t the reaction rate of alcoholysis increases with temperature, b u t no quantitative data were offered to indicate the extent of this acceleration o r its effect on the composition o f the reaction product. W r i g h t , et al. (14), investig a t e d the ethanolysis of cottonseed a n d coconut oil with the idea of establishing the effeet of the variables, ethanol, water, and alkali, on the yield of glycerol Their primary interest was to show exactly how various amounts o f w a t e r lowered the glycerol yield and how excess sodium hydroxide and/0r alcohol compensated in some measure f o r the presence o f water. They did not report reaction times and temp e r a t u r e s ; and, like Toyama and co-workers, stated the reactions were complete in a n hour o r two. Bradshaw (2) described the process of alcoholysis in connection with the preparation of soaps and recovery o f glycerol b u t presented very little experimental d a t a .Several investigators (4, 6, 9), employing conditions o t h e r than those described above, have f o u n d that when alcohol, fat, and alkali are allowed to interact, the aeetyl value of the fatty portion obtainable from such a mixture increases to a m a x i m m n value and then decreases with time; and there is agreenlent as to the different types of compom~ds to be f o u n d in a reacting' mixture. It has been claimed by Toyama and Tsuchiya (11) t h a t the a c e t y l value o f the reac-

Biodiesel Fuel from Animal Fat. Ancillary Studies on Transesterification of Beef Tallow

“…The results are similar to the solubility of ethanol in peanut oil. 12 For the transesterification of beef tallow with methanol, stirring was necessary to mix the two phases well and to increase the reaction areas between the two phases. During the progress of the reaction, some intermediates, such as monoglycerides and diglycerides, were formed and acted as emulsifiers.…”

Biodiesel: visão crítica do status atual e perspectivas na academia e na indústria

“…Esse combustível, hoje poderia ser chamado de "óleo de Chavanne" em homenagem ao autor da brilhante idéia que fez possível a rodagem do primeiro ônibus "movido a biodiesel" já em 1938, na linha comercial de passageiros entre as cidades de Louvain e Bruxelas, na Bélgica, 17 mas que, no entanto, passaria a ser chamado de biodiesel, apenas a partir de artigo publicado em 1988 por Wang. 18 o desenvolvimento da reação de transesterificação de óleos vegetais com um álcool como o metanol ou etanol, sob catálise alcalina, [19][20][21][22][23][24] foi registrado em vários artigos 19,20 e patentes [21][22][23][24] nas décadas de 40 e 50. Apesar dos estudos de Chavanne 16,17 citarem o uso desses ésteres como combustível, as referidas patentes [21][22][23][24] destacam os processos inventados, com outras finalidades como, por exemplo, para o uso da glicerina.…”

Production of biodiesel from vegetable oils

“…the maximum free fatty acid content must be at most 0.5% (Ma et al, 1998;Bradshaw and Meuly, 1944;Feuge and Grose;1949). This parameter is, nevertheless, less critical than the water content.…”