Zane Šustere

The composition of commercial acetylated glycerol samples determined by 13C and 1H NMR. The comparison with gas chromatography

A convenient method for the analysis of commercial acetylated glycerol samples based on 13C NMR is presented with the accuracy comparable to the standard gas chromatography approaches. The advantage of method is that it does not need any sample derivatization procedure by silyl groups and its application is much more straightforward, as compared to the published 1H NMR method.

Competitive Interesterification-Transesterification of Rapeseed Oil with Methyl Acetate in Presence of Potassium Metoxide Solutions

Two catalytic systems (CH3OK/CH3OH and CH3OK/tert-BuOH) were tested to estimate competitive interesterification-transesterification processes of rapeseed oil with methyl acetate. Catalyst completely dissolves in methanol, while in tert-butanol suspension was obtained. With CH3OK/CH3OH catalytic system high FAME content was obtained (86 wt%), but triacetin content was negligible and without FAME mostly transesterification products of oil and triacetin were observed (up to 94 wt% of all products). When CH3OK/tert-BuOH catalytic system was used, only interesterification of oil proceeded, nevertheless the composition of product complicated the interesterification of triacetin with tert-butanol.

Production of Biodiesel and Triacetin by Interesterification of Rapeseed Oil

Interesterification of vegetable oils is one of the methods which have been considered for biodiesel production. Average yield of fatty acid methyl esters (FAME)/triacetin (TA) containing product mixture obtained under developed optimal rapeseed oil (RO) interesterification reaction conditions reached 117.2%. Treatment of FAME/TA mixture with three different commercial ion exchange resins (Amberlyst-A26 (OH-), Amberlyst-15 (H+), Lewatit GF 202 (Na+)) and water was investigated to improve fuel properties or extract FAME and TA as two separate marketable products. Fuel properties of obtained product mixtures were relatively close to biodiesel obtained from RO by transesterification reaction with methanol. The highest influence on chemical composition of product mixture showed water as treatment agent. Water can be successfully used as extraction agent for separation of TA and other glycerol (G) acetates from fatty acid moiety containing compounds. Two separate product mixtures were obtained after treatment of FAME/TA containing mixture with water. G (~5 wt.%), DAG (~33 wt%) and TA (~61 wt.%) mixture extracted with water using developed method has high potential for application in different industrial areas. Rest of product mixture with high content of FAME (~77 wt.%) could be used as renewable fuel for diesel engine exploitation.

GC Analysis of Biodiesel Synthesis Reaction Mixtures Formed in Rapeseed Oil Reaction with Ethyl Acetate

GC Analysis of Biodiesel Synthesis Reaction Mixtures Formed in Rapeseed Oil Reaction with Ethyl Acetate There are publications concerning the studies on interesterification of oils with methyl and ethyl acetate using immobilized lipase as a catalyst. With this approach, triacetin (TA) could be produced instead of glycerol as the main by-product, possessing a much higher commercial value. In this study, the synthesis of biodiesel (BD) by interesterification of triglycerides (TG) and ethyl acetate in the presence of sodium methoxide catalyst has been investigated. Apart from the BD and TA, the reaction mixture may contain intermediates, such as diacyl monoacetyl glycerols (DiGlAc) and monoacyl diacetyl glycerols (MonoGlAc2). Sodium methoxide solution in methanol as a catalyst may yield also such products as monoglyceride, diglyceride and glycerol in low concentrations. The reaction mixture may also contain unreacted TG and undistilled ethyl acetate. In the case of interesterification with ethyl acetate, the degree of conversion may be low, so that the known method (EN 14105) cannot be applied because the TG concentration falls outside the conventional calibration range. In order to obtain the information concerning the composition of interesterification reaction mixtures, a new calibration procedure for the determination of TG in the range from 0.5% to 80% (wt %) was developed in the present study, and the peaks of DiGlAc and MonoGlAc2 were identified. Rapšu Eļļas Pāresterificēšanas Ar Etilacetātu Reakcijas Maisījumu Gāzhromatogrāfiska Analīze Pāresterificējot eļļu ar metil- un etilacetātu, veidojas biodīzeļdegviela un triacetīns, kurš atšķirībā no glicerīna ir daudz vērtīgāks. Literatūrā pieejami šāda veida reakciju pētījumi, kurās kā katalizatorus izmanto ekstragētas lipāzes. Lai iegūtu jaunu informāciju par reakcijas ar etilacetātu realizācijas iespējām, veicām šādas pāresterificēšanas reakcijas līdzsvara pētījumus, kā katalizatoru izmantojot nātrija metanolātu. Bez biodīzeļdegvielas un etilacetāta, reakcijas maisījums var saturēt starpproduktus - monoacildiacetilglicerīdus un diacilmonoacetilglicerīdus. Katalizators, nātrija metanolāta 30% šķīdums metanolā, reakcijas maisījumā var veidot arī monoglicerīdus, diglicerīdus un glicerīnu zemās koncentrācijās. Turklāt reakcijas maisījumā var būt arī neizreagējušie triglicerīdi un neatdestilētais etilacetāts. Interesterifikācijas gadījumā konversijas pakāpe var būt zema, tādējādi standartmetodi EN 14105 nevar lietot triglicerīdu noteikšanai. Lai noteiktu reakcijas maisījumu sastāvu, veikta kalibrēšana triglicerīdu noteikšanai intervālā no 0.5-80% (sv. %) un uz hromatogrammām identificētas monoacildiacetilglicerīdiem un diacilmonoacetilglicerīdiem atbilstošas smailes.