Recent Researches in Engineering and Automatic Control

Comparing the biodiesel and biogasoil production from different natural triglycerides JENİ HANCSÓK, ZOLTÁN VARGA, SÁNDOR KOVÁCS, TAMÁS KASZA MOL Department of Hydrocarbon and Coal Processing University of Pannonia Egyetem str. 10., Veszprém, H-8200 HUNGARY [email protected], http://olaj.mk.uni-pannon.hu Abstract: - Regarding the sustainable mobility, product quality and environmental aspects fatty acids methyl esters and biogasoils were compared. They were produced by the transesterification and special hydrocracking (including the isomerization, as well) of triglycerides, respectively. It was concluded that the 10 energy percent biofuel share will be attained in the EU up to 2020 only by building of new biogasoil plants beside the currently working biodiesel plants. In medium and long-term, probably the fuel purpose hydrogenation of natural and waste triglycerides will be spread in higher and higher degree.

Key-Words: - biodiesel, biogasoil, feedstock supply, quality comparison. feedstocks (e.g. wood processing, forestry and agricultural wastes, etc.), the hydrogenated bio-oils produced from agricultural wastes by pyrolysis [13] and other bio-paraffins and bio-hydrogen produced by many different methods [14] belong to the first group. The so-called biogasoils belong to the second group. They are the mixture of iso and normal paraffins which can be produced by the special hydrocracking of different natural triglycerides and/or fatty acids [8], [9], [15]-[24]. Their industrial scale production has already started in some refineries [25]. Accordingly, fatty acid alkyl(metyl) esters and biogasoils can be concurrent products regarding the feedstock supply. Consequently the comparison of their production technologies (industrial processes) and product quality are necessary.

1 Introduction Fuels produced from agricultural products or wastes had a high importance in the last 10-15 years. In case of spark ignition engines bioethanol is still produced from first generation feedstock (e.g. corn, waste grains, etc.) in the expected quality and quantity [1]. In case of Diesel engines the most prevalent fuels (>95%), the biodiesels (fatty acid methyl esters) are produced by acidic [2], [3] or enzymatic [3], [4] transesterification. However, they cannot satisfy either the quantity, or the quality demands. The reason of the quantity barrier is the insufficient quantity of feedstock (e.g. vegetable oils, used frying oils and fats, etc.) [5], [6]. The quality problem comes from the disadvantageous utilization properties of fatty acid methyl esters such as poor storage (oxidation and heat) stability because of the olefinic double bonds of the molecule; hydrolysis sensitivity of ester bonds, which results the formation of corrosive acids; unfavorable cold flow properties; metal and phosphorous content, etc [7]-[9]. Accordingly intensive research activity started in the recent past to develop new alternative fuels that can be used in Diesel engines (Table I.) [8], [9]. Some of them have totally different feedstock supplies than biodiesels, while that of some fuels partially overlaps with that of biodiesel. Regarding the feedstock supply the synthetic gas oils [10], [11] and dimethyl-ether [11], [12] produced by Fischer-Tropsch synthesis form synthesis gas via gasification of many kinds of

ISBN: 978-1-61804-057-2

2 Experimental Based on the abovementioned we present the main results of our experiment of biodiesel and biogasoil production; the quality properties of products and those critical evaluations obtained in case of different triglycerides as feedstock.

2.1 Apparatuses and methods 2.1.1 Transesterification apparatus and experimental method Transesterification experiments were catalysed by sodium-methylate and an enzyme catalyst. The

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Recent Researches in Engineering and Automatic Control

TABLE I. CATEGORIZATION OF ALTERNATIVE FUELS OF DIESEL ENGINES ACCORDING TO THE CHRONOLOGY OF THEIR DEVELOPMENT AND APPLICATION GENERATION first second third fourth biogasoils (special synthetic bio-fuels from synthesis bio-hydrogen vegetable oils hydrocracking of gas triglycerides) synthetic gasoil (hydrocracking synthetic bioof bio-oils produced by biomass methane pyrolysis)

bio-paraffins from hydrocarbons, lignocelluloses

bio-methane (bio gas) biodiesels

yet unknown

dimethyl ether (DME)

blends of the previous and conventional petroleum-based fuels

alkali-methylate catalysed transesterifications were carried out in a known apparatus [26] at 60°C; 4:1 methanol:triglyceride molar ratio; 2% catalyst and 180 minute reaction time. After 7 hours sedimentation time phases were separated. Methanol was removed from the fatty acid methyl esters phase by vacuum distillation. Using ion exchange resin the product was purified, then its mass and main characteristics were determined (EN 14214). The first enzyme catalysed transesterification experiments were carried out in New Brunswick G24 shaking incubator. In this apparatus nine parallel experiments can be done at the same time, assuring the same conditions. The degree of shaking and the temperature could be controlled. These values had less than 1% differences at the parallel measurements. The vegetable oil (44 g in every case) and enzyme were shaken at different temperatures and through different reaction times [27]. To produce a higher amount of product and to separate the glycerine by dialysis we used another apparatus (Fig.1). The system contained an asymmetric, hydrophilic ultrafiltration membrane made of cellulose acetate (surface area: 100 cm2, membrane cutting number: 40 kDa). Based on our pre-experiments the process parameters were the following: temperature: 50 ± 1°C; pressure: atmospheric; methanol:triglyceride molar ratio: 4:1; catalyst: 9% immobilised enzyme (relative to reaction mixture), reaction time: 12 hours; methanol addition in 9 portions. The dialysis was started only in case of an adequate degree of conversion. The glycerine free reaction

ISBN: 978-1-61804-057-2

Fig.1 Theoretical scheme of the apparatus used for enzyme catalysed transesterification

product was recycled until almost total conversion was reached. After the separation of glycerine, the surplus methanol was removed by vacuum distillation from the ester phase, and then further purification was carried out over the ion exchange resin. The used immobilised enzyme can be regenerated with iso-prolyl-alcohol. 2.1.2 Special hydrocracking and isomerization apparatus The catalytic reactions were carried out in a bench scale, high pressure reactor system containing two fixed bed flow through reactors with 100-100 cm3 catalyst volume (Fig. 2) [8], [9]. It contains all the equipment and devices applied in the reactor system

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Recent Researches in Engineering and Automatic Control

Fig.3 Scheme of the separation of the product mixture made by heterogeneous catalytic hydrogenation of vegetable oil/gas oil mixtures Fig.2 Simplified scheme of the test apparatus (1 reactor; 2 pre-heater; 3 oxygen converter; 4, 5 gas dryer; 6,10 gas filter; 7 gas flow meter; 8 gas flow meter; 9 demister; 11 compressor; 12, 13 burettes for liquid feed; 14 pump; 15, 18 cooler; 16 separator; 17 level meter; 19 closing valve; 20 control valve; 21 back valve; 22 manometer)

The residue of atmospheric distillation was separated by vacuum distillation into the main product (gas oil boiling range fraction, mainly C11C22 hydrocarbons up to 370°C) and the residue. At the investigated parameter combination small amount (