ITRM20060120A1 - USE OF NON SAPONIFIABLE MATERIALS OF VINEGAR SEED OIL AS AN ANTIOXIDANT ADDITIVE FOR BIODIESEL - Google Patents

Description

Description of the industrial invention entitled: "USE OF NON-SAPONIFIABLE MATERIAL OF GRAPE SEED OIL AS ANTI-OXIDANT ADDITIVE FOR BIODIESEL"

DESCRIPTION

The present invention relates to the use of unsaponifiable matter (USM) obtained from grape seed oil (GSO) as an antioxidant additive for fuels of vegetable origin for internal combustion engines, in particular for diesel engines. These fuels of vegetable origin will be generically referred to hereafter as biodiesel.

The use of fuels derived from natural sources has grown in recent years substantially due to two factors: on the one hand the increase in the cost of oil, on the other hand the increased sensitivity to environmental problems. However, as better explained below, a strongly limiting factor in the use of these fuels is the fact that they are subject to oxidation processes during the storage, distribution and use phases.

Biodiesel is a fuel produced from natural and renewable sources, such as vegetable oils and fats, by transesterification using alcohol in the presence of a catalyst. This fuel can, for example, be produced by transesterification of vegetable or animal oils or fats prepared from different raw materials, in particular turnip oil (Brassica napus), soybean oil, sunflower oil or used frying oil, made react with methanol / ethanol. Biodiesel has some advantages such as a reduced emission of unburned hydrocarbons, carbon monoxide, sulfates, polycyclic aromatic hydrocarbons and particulate matter. The main disadvantage of biodiesel is that it is more prone to oxidation than fossil fuels. Oxidation causes an increase in acidity which, in turn, favors the onset of corrosion phenomena in the fuel supply system and the formation of insoluble gums and sediments. The effect of the above is an increase in viscosity with negative consequences also on the operation and efficiency of the engine. Furthermore, oxidation damages the quality of the fuel during storage, which is not a secondary aspect, taking into account that, in some countries, particularly in Italy, biodiesel must be stored for long periods to meet strategic needs.

Although natural components that inhibit oxidation are present in the starting materials for the production of biodiesel, these are largely removed during the processing of biodiesel and therefore cannot perform their function.

To slow down the oxidation phenomenon, the use of antioxidant substances has been proposed. Antioxidants are substances which, although present at low concentrations and, or quantities compared to those of an oxidizable substrate, significantly delay or completely prevent the oxidation of the same substrate (Gordon 1995). With this in mind, to stabilize the biodiesel, the use of synthetic antioxidants such as pyrogallol, pyrogallate, TBHQ and BHA has been proposed. This solution encountered two kinds of difficulties. First, a considerable increase in costs; in addition, the frequent dangerousness and harmfulness of the substances used. For example, TBHQ has been confirmed to produce lung damage and promote tumors in mice.

The above considerations have sparked interest in plant-based antioxidants.

Among the families of compounds examined, tocopherols can be mentioned which stabilize methyl esters (a family of components of biodiesel) by reducing the rate of peroxide formation and, at the same time, increasing the period necessary to reach the level of peroxides that causes the beginning of the increase in viscosity. The effect of tocopherols and carotenoids on the oxidation stability of the sunflower methyl ester (one of the components of biodiesel) was also evaluated, using a- and δ-tocopherol in different concentrations. The study showed that δ-tocopherol is more active, the maximum of activity being at concentrations of 500 mg / kg. The antioxidant activities of individual tocopherols in biodiesel fuels have been studied within the BIOSTAB project but the indications obtained were simply qualitative, as the exact type and origin of tocopherols and, above all, the optimal quality of these have not been determined. exactly.

The need was therefore felt in the state of the art to make fuels of vegetable origin available, in particular for diesel engines, with improved resistance to oxidation, a resistance obtained in such a way as to allow use compatible with the environment.

It has now been surprisingly found that unsaponifiable matter of grape seed oil can be advantageously used as an antioxidant additive in fuels of vegetable origin.

Therefore, the subject of the present invention is the use of unsaponifiable matter obtained from grape seed oil as an antioxidant additive in fuels of vegetable origin for internal combustion engines, in particular diesel engines.

Brief description of the drawings

Attached to this description are 10 tables showing:

Figure 1 the induction time of a biodiesel with the addition of 0.01% weight / weight of tocopherols and tocotrienols;

figure 2 the induction time of the same biodiesel with the addition of 0.02% weight / weight of tocopherols and tocotrienols;

figure 3 the induction time of the biodiesel with the addition of 0.05% weight / weight of tocopherols and tocotrienols;

figure 4 the induction time of the biodiesel with the addition of 0.1% weight / weight of tocopherols and tocotrienols;

figure 5 the induction time of the biodiesel with the addition of 0.2% weight / weight of tocopherols and tocotrienols;

figure 6 the induction time of the biodiesel with the addition of 0.01% weight / weight of unsaponifiable matter of grape seed oil

figure 7 the induction time of the same biodiesel with the addition of 0.02% weight / weight of unsaponifiable matter of grape seed oil

figure 8 the induction time of the biodiesel with the addition of 0.05% weight / weight of unsaponifiable matter of grape seed oil;

figure 9 the induction time of the biodiesel with the addition of 0.1% weight / weight of unsaponifiable matter of grape seed oil; and Figure 10 shows the induction time of the biodiesel with the addition of 0.2% weight / weight of unsaponifiable matter of grape seed oil.

The unsaponifiable matter (USM) of grapeseed oil (GSO) used in the field and produced according to the process of the present invention also contains minor quantities of other compounds including sterols, 4-methyl sterols, triterpene alcohols, tocopherols, tocotrienols, compounds phenolics, hydrocarbons (squalene).

It should also be emphasized that the present invention, using waste products from the cultivation of the vine and the wine industry in general, presents an undoubted advantage in terms of environmental policy and impact on the territory.

Detailed description of the invention

The residue of industrial processing of grapes called "pomace", consists mainly of grape seeds, skins and stems. Grapeseed seeds (Vitis Vinifera L.) contain a percentage of 6-21% by weight of oil, depending on the single variety, a quantity that makes extraction possible and economically advantageous. Extractions using the cold press method still leave about 4% of the oil in the residue and the solvent extraction method leaves about 1%.

The unsaponifiable matter of the invention can be produced according to the following methodology which includes the following operations:

(1) Extraction of grape seed oil.

The seeds are separated from the residues of industrial processing of the grapes by washing to remove the pulp, then dried and the oil is extracted with the so-called soxhlet method, for example using petroleum ether as a solvent (boiling point: 30 ° C - 60 ° C);

(2) Extraction of the unsaponifiable matter: After evaporation of the solvent, the oil samples undergo a saponification and the unsaponifiable substance is extracted using diethyl ether according to the AOAC procedure, no. 933.08 (1990). After removal of the solvent, for example by using a rotary vacuum evaporator, the residues are solubilized in diethyl ether.

(3) For the isolation of tocopherols and tocotrienols, chromatographic techniques, TLC (thin layer chromatography pre-coated with kilsegel 40 in n-hexane: diethyl ether in the ratio 4: 1) are used. The members of the USM are separate and in their respective zones; the third zone consisting of tocopherols and tocotrienols, after identification under UV rays of the single components (250 nm) was extracted from the layer and purified with diethyl ether.

(4) The tocopherols, tocotrienols and USM of GSO obtained from the previous step are added in different percentages to the same type of biodiesel. In particular, two series of biodiesel samples were prepared with the addition of 0.01%, 0.02%, 0.05%, 0.1% 0.2% weight / weight respectively of tocopherols, tocopherols and tocotrienols and of USM extracted from GSO. A sample of biodiesel was also prepared without any additives (control).

The biodiesel used in the present invention was obtained with known technologies starting from sunflower oil of the Carnia variety reacted with methanol (20%) and lye (0.035%). Glycerin was also obtained as a by-product. All the experimental data reported in the present application were obtained with biodiesel as just indicated.

In principle there are different methods for the determination of the oxidative stability of and of fats; these are referred to as Rancimat and Schal oven Storage test AOM (method with active oxygen) and OSI (oxidative stability instrument). In particular, the data shown below were obtained through the Rancimat and Schal oven Storage tests.

The schal oven Storage test method is a simple, fast and reliable method in which the samples are stored in an oven at a temperature of 25-80 ° C (in this specific case 70 ° C) with a repeated check of the peroxide value. In the present case this test was performed following the AOCS Cd 8b-90 methodology. Another series of samples was used to terminate the induction time according to the Rancimat method with the Rancimat Metrohm instrument which allows the identification of the starting point of rancidity, of the accelerated phase and the end point of rancidity; this method was performed following the ISO 6886 procedure. In order to determine the oxidative stability by the Rancimat method, a stream of air is blown through the samples (10 liters / h) with the heating system temperature set to 110 ° C . At this temperature there is the oxidation of the fatty acids and / or of the methyl esters of the fatty acids. In general, oxidation takes place according to a radical chain mechanism that produces easily volatile oxidation products (mainly formic acid). These short-chain carboxylic acids are transferred by the air stream into a measuring vessel containing deionized water whose conductivity is continuously measured (0 to 400 μS / cm ± 0.1 μS / cm). Following on the graph the conductivity as a function of time we obtain the oxidation curve whose inflection point is known as the induction time. The determination is completed automatically. The time / conductivity curves of different biodiesel samples containing various percentages of tocopherols, tocopherols and tocotrienols, and USM of GSO are shown in the attached figures (Figures 1 - 11). The longer induction time (IT) in Figures 9 and 10, in the biodiesel samples containing 0.1% and 0.2% USM of GSO respectively, indicates that the amount of this additive added to the biodiesel is sufficient to ensure effective preservation of the biodiesel itself.

Therefore, in the context of the present invention, quantities of USM of GSO to be added to the biodiesel for efficient stabilization vary from 0.05 to 0.3%, preferably from 0.1 to 0.2% by weight based on the biodiesel weight.

The reaction induction time (RIT) is the time necessary for the sample under the conditions of preparation of temperature at a current of air to arrive at the considered reaction. In this specific case the reaction considered is the oxidation and the production of final oxidation products aldehydes and ketones at a certain concentration, is able to modify the conductivity of deionized water. In the specific case, the induction time can be defined as the time needed to cause a defined reaction.

The term stability index refers to the ratio between the induction time of biodiesel added with antioxidant and the induction time of pure biodiesel (Table 1).

Table 1- Stability Index of Biodiesel Contain Different Amounts of Grapeseed Oil Derivatives (as Percentage of Biodiesel Weight w / w)

Stability Index = Induction time (antioxidant biodiesel) / Induction time (pure

Biodiesel)

The results reported in table 1 show that, with the same concentration of added additive, adding USM to biodiesel has obtained a greater stability (measured in terms of induction time) of the biodiesel compared to blends of tocopherols, and of tocopherols and tocotrienols, stability which is also significantly higher than tocopherols alone in the same concentration which accounts for a synergistic effect of other components of the USM on the stability of biodiesel.

A determination was also performed

the oxidative stability of biodiesel in samples including the various percentages of USM using a rapid and reliable method such as "schal oven Storage test". According to this method, the samples were stored in an oven at temperatures between 25-80 ° C (in the present experiment 70 ° C) and a repeated control of the peroxide value was performed following the AOCS Cd 8b -90 methodology (Table 2).

Table 2- Comparison between the peroxide values. Student-Newman-Keuls Test

The following means of the same reading are not significantly different at 1% as indicated by the Student-Newman-Keuls Test

From Table 2 it is evident how the addition of USM to biodiesel improves its quality and durability by reducing the formation of peroxides.

According to the present invention, as confirmed by the attached experimental data, the addition of USM of GSO to the biodiesel is suitable for improving the stability of the biodiesel itself. The addition of this material does not create changes in the dispensing device as well as in the nature of the final product ie biodiesel. Since the heating system is connected with the external environment and some of the synthetic antioxidants such as TBHQ are dangerous (lung disease and tumor induction in mice) it is beneficial to limit the use of these and use natural antioxidants. The antioxidant mentioned on the other hand is obtained from waste material and therefore has no environmental impact.

After intense research, not only the type of antioxidants but its effective amount (i.e. 0.3 preferably 0.1% -0.2% of USM of GSO) as well as the optimal stability required (Oxidation stability of BD at 110 ° C according method) were determined. EN 14112 should be minimum 6 hours) in the addition to biodiesel (see Table 2). The results demonstrate that the natural stabilizing factors of GSO are effective antioxidants for biodiesel.

Claims (5)

CLAIMS Use of unsaponifiable matter obtained from grape seed oil as an antioxidant additive in fuels of vegetable origin for internal combustion engines. Use according to claim 1, wherein said internal combustion engines are diesel engines. 3. Use according to at least one of the preceding claims, wherein said unsaponifiable matter is added to said fuels in a quantity comprised between 0.05 and 4. Use according to claim 3, wherein said unsaponifiable matter is added in a quantity comprised between 0.1 and 0.2%. 5. Fuel for internal combustion engines containing unsaponifiable matter obtained from grape seed oil.