Title Ispitivanje utjecaja reakcijskih uvjeta na sintezu heksilnih estera masnih kiselina Title (english) Influence of reaction parameters on the synthesis of hexyl esters of fatty acids Author Matija Krvavica Mentor Fabio Faraguna (mentor)Committee member Fabio Faraguna (predsjednik povjerenstva)Committee member Elvira Vidović (član povjerenstva)Committee member Marin Kovačić (član povjerenstva)Granter University of Zagreb Defense date and country 2022-09-12, Croatia Scientific / art field, TECHNICAL SCIENCES Abstract Biodizel je ester masnih kiselina koji se najčešće sintetizira reakcijom transesterifikacije triglicerida (biljna ulja i životinjske masti) s alkoholom u prisustvu katalizatora. Proizvodnjom od otpadnog ulja, eliminiraju se dodatni troškovi uzgoja biljaka uljarica, štede se plodne površine i voda, izbjegava se kompeticija s hranom što može dovesti do rasta cijena i nedostatka hrane (jestiva biljna ulja) te se smanjuje nastanak otpada u prehrambenom sektoru. Struktura molekule biodizela ovisi o sirovinama od kojih se sintetizira. Masne kiseline triglicerida uglavnom su ravnolančane, stoga molekula alkohola određuje hoće li ester biti razgranat ili ravnolančan. Oblik molekule je odlučujuć za neka svojstva dizelskog goriva. Primjerice, duže ravnolančane molekule povećat će vrijednost cetanskog broja, dok će razgranati esteri sniziti tecište što će omogućiti rad pri nižim temperaturama. Cetanski broj je primarni indikator kvalitete goriva korištenog u kompresijskim motorima s unutarnjim izgaranjem. Neki biodizeli pokazuju visoke vrijednost cetanskog broja, no dokazano je kako su dulji ugljikovodični lanci u molekulama estera proporcionalno povezani s vrijednosti cetanskog broja. U tu svrhu istražuju se sinteze s višim alkoholima poput 1-heksanola. U ovom radu ispitivani su utjecaji reakcijskih parametara na iskorištenje reakcije transesterifikacije otpadnog ulja s heksanolom. Pratio se utjecaj molarnog omjera alkohol/ulje, utjecaj masenog udjela lužnatog katalizatora KOH, utjecaj reakcijskog vremena i temperature. Iskorištenje se određivalo iz 1H NMR spektra integriranjem površine pojedinih signala. Eksperimentalnim dijelom rada utvrđeno je da se najveće iskorištenje dobiva pri temperaturi od 60 °C. Veće iskorištenje reakcija je imala s molarnim omjerom alkohol/ulje 12:1. Veći suvišak alkohola ovu je ravnotežnu reakciju pomaknuo više prema produktima. Maseni udio katalizatora od w(KOH) = 3 % dao je veća iskorištenja reakcije u odnosu na w(KOH) = 1 %. Visoka iskorištenja reakcije dobila su se već nakon 2 minute, no do 15. minute iskorištenje se u prosjeku još povisilo za 1,59 % i doseglo svoj maksimum. Eksperimentalno je pokazano da na iskorištenje najviše utječu parametri maseni udio katalizatora te molarni omjer alkohol/ulje.
Abstract (english) Biodiesel fuel is a fatty acid alkyl ester, commonly synthesized via transesterification of triglycerides (vegetable oils and animal fats) with an alcohol, in a presence of a catalyst. Production of biodiesel fuel from waste vegetable oil eliminates additional costs of growing oilseed plants as a raw material, reduces the amount of waste in the food sector, preserves fertile land area and water, eliminates direct competition with food which could otherwise potentially lead to price increase and shortages of edible vegetable oils. The structure of the biodiesel molecule depends on the feedstock from which it's synthesized. The triglyceride’s fatty acids have mainly straight hydrocarbon chains, so the alcohol molecule determines if the ester will be straight-chained or branched. The molecule structure is determinant for some diesel fuel properties. For example, longer straight-chained molecules will have higher cetane number values, while branched ones will have lower pour point values and, therefore, engines will be able to perform at lower temperatures. Cetane number is the prime indicator of the fuel quality used in the internal combustion compression engines. Some biodiesel fuels show high cetane number values. It has been proven that longer hydrocarbon chains in the ester molecules are proportionately related to the cetane number value, therefore, synthesis with higher alcohols are being tested, such as 1-Hexanol. In this research, the influence of reaction parameters on the transesterification process of waste vegetable oil with 1-Hexanol was examined. The influence of the alcohol/oil molar ratio, the influence of the mass fraction of the alkaline catalyst KOH, the influence of the reaction time and temperature were monitored. The conversion was calculated from 1H NMR spectra by integrating the surface areas of specific signals. The experimental part of the research established that 60 °C is the best temperature out of given three in the reaction. 12:1 alcohol to oil molar ratio had a higher conversion because greater excess of an alcohol shifted this reversible chemical reaction more towards the products. The catalyst mass fraction of w(KOH) = 3 % gave higher reaction yields than the 1 % one. High conversions of the reaction were obtained after only 2 minutes, but by the 15th minute the conversion increased by approximately 1.59 % and reached its near maximum. It was experimentally shown that the parameters that have the greatest effect on conversion are the mass fraction of the catalyst and the alcohol to oil molar ratio.
Keywords
biodizel
otpadno ulje
heksanol
transesterifikacija
reakcijski parametri
Keywords (english)
biodiesel
waste vegetable oil
1-hexanol
transesterification
reaction parameters
Language croatian URN:NBN urn:nbn:hr:149:587242 Project Number: UIP-2019-04-5242 Study programme Title: Environmental Engineering - Undergraduate study Type of resource Text File origin Born digital Access conditions Access restricted to students and staff of home institution Terms of use Created on 2023-03-17 14:52:10
