Determining the influence of reaction parameters on the synthesis of isobutil fatty acid esters

Biodizel je ekološki prihvatljiva i održiva zamjena za petrokemijski dizel. Prema kemijskom sastavu biodizel obuhvaća monoalkilne estere masnih kiselina i jednostavnih alkohola. Sirovine za proizvodnju biodizela čine razna biljna i otpadna ulja poput suncokretovog, repičinog ulja te ulja kikirikija i soje, dok su od alkohola za sada najzastupljeniji metanol i etanol. U posljednje vrijeme istražuje se mogućnost korištenja i drugih alkohola poput butanola, izobutanoal i pentanola kao sirovina za proizvodnju biodizela. Biodizel se proizvodi reakcijom transesterifikacije ulja s alkoholom. U ovom radu obrađen je utjecaj četiri reakcijska parametra na bazno kataliziranu transesterifikaciju suncokretova ulja s izobutanolom uz kalijev hidroksid kao katalizator. Parametri čiji utjecaj je određivan su: vrijeme reakcije (1 - 3 h) , temperatura (40 - 80 °C), molarni omjer alkohola i ulja (6:1 - 12:1) te maseni udio katalizatora (1 - 3 %). Pomoću programskog paketa Desin-Expert 11 napravljen je Box-Behnkenov plan 28 pokusa. Rezultat svakog pokusa je iskorištenje reakcije. Iskorištenje je određeno pomoću 1H NMR analize reakcijske smjese. Na temelju eksperimentalnih rezultata napravljen je model ovisnosti iskorištenja o reakcijskim parametrima. Dobivenim modelom napravljena su tri slučaja optimizacije. Optimalni uvjeti za jedan od slučajeva su: vrijeme reakcije od 1 sat pri temperaturi od 71,98 uz omjer izobutnola i ulja 10,17:1 sa 1,72 % KOH katalizatora. Previđeno iskorištenje iznosi 99,69 %. Biodiesel is ecologically acceptable a sustainable substitute for petrochemical diesel. By its chemical composition biodiesel is a mixture of monoalkyl esters of fatty acid and simple alcohols. Biodiesel is produced from different waste and cooking oils such as sunflower, castor, peanut and soybean oils. Nowadays, most used alcohols are methanol and ethanol. In recent times, other alcohols, such as butanol, isobutanol and pentanol, are being investigated for biodiesel production. Biodiesel is produced by the reaction of transesterifiction of oil with alcohol. In this paper, the influence of four reaction parameters on base catalysed transesterificaton of sunflower oil with isobutanol was studied. Potassium hydroxide was used as catalyst. Reaction parameters were: reaction time (1 - 3 h), temperature (40 - 80 °C), molar ratio of alcohol and oil (6:1 - 12:1) and mass percentage of catalyst (1 - 3 %). Using Desin-Experst software a Box-Behnken plan with 28 experiments was made. Result of every experiment was the biodiesel yield which was determined by 1H NMR spectroscopic analysis. Based on the experimental results, a model of the dependence that takes into account the yield on the reaction parameters was made. Using the model three optimisation cases were made. Optimal reaction parameters for one of those cases were: 1 h of reaction time at 71.98 °C using 10,17:1 ratio of isobutanol and oil and 1.72 % of KOH catalyst. The estimated yield was 99.69%.