OA20823A - Process for transforming vegetable oils into biodiesel and other by-products - Google Patents

Abstract

The invention relates to a process for transforming vegetable oils obtained from the seeds of Hevea brasiliensis, into a chemical composition that can be used as biodiesel and other derived products, by the processes of transesterification and glycerolysis. Rubber seed oil is obtained after dehulling, grinding, cooking and subsequent extraction by pressure and solvent. It is then esterified to reduce its free fatty acid content using glycerol and thus increase the yield of the transesterification reaction.

Description

DESCRIPTION OF THE INVENTION

Process for transforming vegetable oils into biodiesel and other by-products

The present invention relates to the field of energies and concerns the production of a chemical composition that can be used as a second-generation biofuel, in particular a process for the production of biodiesel from rubber tree seeds, Hevea brasiliensis, used as raw material.

The invention also relates to the biodiesel obtained from the implementation of the transformation process.

The rubber tree, the rubber tree or the Brazilian rubber tree (Hevea brasilîensis) is a species of tree, of the genus Hevea of the Euphorbiaceae family. We mainly extract a latex which is used to be transformed into rubber.

Côte d'Ivoire, a small natural rubber producing country a decade ago, is now one of the world's largest producers of rubber. Indeed, from 170,000 tons in 2005, Ivorian rubber production, the first in Africa, has continued to grow, going from 602,000 tons in 2018, 783,000 in 2019 to 950,000 tons in 2020, to reach the 4th position in the world. with an orchard covering more than 650,000 ha.

When ripe, Hevea brasiliensis gives dehiscent fruits which are composed of a three-celled capsule each containing a seed of about 2 cm, oval, brown in color decorated with whitish spots. From these rubber seeds are generated two products: the oil obtained either after pressure or by solvent extraction and cakes. The oil is currently finding outlets in the soap, paint, resin, sealant and biofuel industries, while the cake, obtained after recovering the oil, can be used in animal feed.

A biofuel or agrofuel or biofuel or vegetable fuel, is a fuel, that is to say a liquid or gaseous fuel produced from non-fossil organic materials, originating from biomass. Biofuels represent an additional source of fuel and a new agro-industrial activity. They allow the countries that produce them to reduce their energy dependence on fossil fuels. Their frantic development these days can also be explained by the fact that the fossil diesel used

[2] is currently negatively impacting the environment with an increase in greenhouse gas emissions, and its high sulfur dioxide (SOz) content.

There are three generations of biofuels, they are:

- first-generation biofuels: they are mainly of two types:

* bioethanol: this is the most developed; it results from the sugar industry and is produced from sugar cane, cereals and sugar beets. It is used in gasoline engines. It is obtained by fermentation of sugars (simple sugars, hydrolyzed starch) by yeasts of the genus Saccharomyces. Ethanol can partially or completely replace gasoline. A small proportion of ethanol can also be added to diesel, thus giving oxygenated diesel, but this practice is rare.

* biodiesel: it comes from the "oil" sector and makes it possible to produce crude vegetable oil and biodiesel (vegetable oil ethyl ester or EEHV). It is derived from different sources of fatty acids, including soybean, rapeseed, palm, and other vegetable oils. It is used in diesel engines.

These so-called first-generation biofuels have the major drawback of entering into direct competition with the food chain. Because they are produced from raw materials that can be used in an animal or human food chain.

- second-generation biofuels: they are obtained using technologies currently being developed to exploit cellulosic materials such as wood, the leaves and stems of plants or those from waste: thus we obtain biodiesel, biohydrogen or biogas. Here, the raw materials used have the advantage of superior availability and non-food competition compared to the first generation of biofuels. It has not yet been deployed at the industrial stage, but prospects for medium-term application are emerging. Their large-scale production is planned for 2020-2030.

- third-generation biofuels: these are less developed forms, or even simply at the research stage. The processes, still under study, are mainly based on the use of microorganisms such as microalgae.

Biodiesel is an ester, produced from a vegetable oil to which an alcohol is added. The ester is miscible with conventional diesel (petrodiesel) and can be used either alone as

[3] fuel, for compatible vehicles, or added to fossil diesel up to 20% (B20), for vehicles that are not suitable for the use of biodiesel alone (B100). Biodiesel is generally produced from other vegetable oils such as palm oil, rapeseed oil, corn oil and used cooking oils.

Biodiesel consists of fatty acid methyl esters based on vegetable oil (FAME), which can be obtained by chemical reaction of transesterification, i.e. reaction of fatty acids (oil or fat) with l alcohol in the presence of a homogeneous or heterogeneous catalyst. The product of this reaction is a mixture of methyl esters (biodiesel) and glycerol (which has no combustible properties). However, obtaining glycerol, a transesterification by-product constituting about 20% of the total reaction product, can be a problem in that it contributes significantly to the decrease in the profitability of a biodiesel manufacturing plant.

To this end, various patents describe processes for the manufacture of biodiesel, addressing the problem of the use of glycerol. For example, the European patent application EP2730567 filed on November 09, 2012 by INST UNIV DE CIÈNCIA I TECNOLOGIA S A, relates to a process for simultaneously obtaining several compositions consisting of alkyl esters of fatty acids (biodiesel), glycerol and bioesters of fatty acid glycerol, the glycerol being used as a substrate for the production of biofuel components. The process for producing the composition involves reacting a triglyceride, glycerol, and diacoxymethane in the presence of an acid catalyst. The reaction product forms two unmixed layers, the upper layer comprising fatty acid alkyl esters, fatty acid glycerol esters, alkyl alcohol and excess diaicoxymethane. The lower layer includes the glycerol and the catalyst.

Application 15808480, filed at ΙΌΕΒ on November 30, 2015 by BIOTIM SPOLKA. Z OGRANICZONA ODPOWIEDZIALNOSCIA, relates to the formation of methyl esters, to be used as biodiesel from vegetable oils containing triglycerides. The process described comprises two stages: the first involves the reaction of methanolysis of triglycerides (vegetable oils) with production of methyl esters (biodiesel) and glycerol phase, i.e. a transesterification process using methanol and potassium hydroxide as a catalyst and the second involves an acidolysis reaction of glycerol obtained in the first stage of the process; which is a reaction of glycerol in the presence of dimethyl sulfate in

[4] excess sulfuric acid as a catalyst in a temperature range of 50 to 55°C to obtain reaction products comprising a polar phase in the form of an ether/ester phase and a non-polar phase; separation of the polar phase from the non-polar phase of the reaction products; distillation of the polar phase to separate the ethers from the esters; and collects ethers and esters in separate tanks.

As we can see, the transesterification process, the basic reaction of the transformation of oils (glycerides) into methyl esters (biodiesel) is not a panacea. Its effectiveness, the quality of the biodiesel obtained and its yield depend on several factors such as the nature and origin of the oils used, the operating conditions of temperature and pressure, the nature of the catalyst used which contribute to its particularity.

The aim of the present invention is to propose another process for the transesterification of triglycerides of fatty acids for the production of methyl esters which can be used as biodiesel from non-food vegetable fat.

In accordance with the invention, this object is achieved with the process for transforming vegetable oils from the seeds of Hevea brasiliensis into a chemical composition that can be used as biodiesel and other derived products by transesterification and glycerolysis.

The implementation of the method according to the invention takes place in several stages. In one embodiment, the seeds of Hevea brasiliensis undergo shelling and the almonds obtained are ground, then the ground material is first cooked under a humid steamer before being pressed to extract most of the oil. The cake obtained still containing oil is depleted of oil using a solvent. The oil with a triglyceric structure thus obtained is filtered before continuing the transformation.

In one embodiment, the filtered oil undergoes glycerolysis to reduce its free fatty acid content to increase the yield of the subsequent transesterification reaction. To do this, the oil extracted from the almonds of Hevea brasiliensis is mixed with glycerol and the mixture is heated. The free fatty acids then esterify the glycerol to give triglycerides.

In one embodiment, all of the oil obtained after glycerolysis undergoes transesterification in the presence of an alcohol which may be ethanol or methanol and of a catalyst; potassium hydroxide, which converts Hevea almond triglycerides

[5] brasiliensis to methyl ester and glycerol. The methyl ester that can be used as biodiesel is separated from the glycerol, then stripped of traces of soap and all other impurities. It is finally stored in a tank which will be used to supply tank trucks for distribution.

Residual glycerol is purified to 99.5% in a dedicated treatment unit and then stored.

The process of transforming vegetable oils from Hevea brasiliensis seeds into biodiesel has the following advantages:

- it makes it possible to increase the income of players in the rubber sector by promoting the seeds of Hevea brasiliensis;

- biodiesel is environmentally friendly because its low sulfur content produces very little greenhouse gas such as sulfur dioxide;

- the biodiesel produced makes it possible to reduce the cost of living by reducing the cost of diesel and therefore of transport, since the seed of Hevea brasiliensis is a very cheap product;

- the process generates by-products that can be used as fuel, or for animal feed or even in cosmetics.

The other characteristics and advantages will appear more clearly in the detailed description illustrated by FIG. 1 of the single board and which only represents a non-limiting example of embodiment.

The invention relates to a process for transforming vegetable oil with a triglyceric structure, originating from rubber tree seeds, into a chemical composition that can be used as biodiesel. In one embodiment, the method takes place according to the following steps:

- husking: the selected and well-cleaned rubber seeds undergo a mechanical treatment which results in the separation of the kernel from the shell. In one embodiment, an hourly throughput of 2 tons of rubber seeds generates 1 ton of kernels and 1 ton of hulls. The huller used is an electric roller huller fitted with a sieve which continuously unloads the shell while the clean almonds are used for subsequent operations;

- grinding: the almonds obtained undergo another mechanical treatment which consists in reducing their size in the form of fine particles in order to facilitate the subsequent expression of the fat;

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- cooking: the ground almonds are steamed. To do this, in one embodiment, a flow of wet steam is injected onto the ground material in order to hydrate it, heat it and cook it. This operation aims to facilitate the simultaneous extraction of free fatty acids and other fats; which increases the yield of the extraction operation.

- extraction: it is done in two stages; crushed, cooked and softened almonds undergo mechanical pressing to extract most of the oil they contain. Then the cake is mixed with hexane or ethanol to extract the rest of the oil. This operation makes it possible to obtain an average of 400 kg of fat for 1 tonne of processed almond,

- filtration: the fat obtained is freed of its impurities thanks to filters. In one embodiment, a vertical bed vibrating filter is used;

- glycerolysis: in order to reduce the content of rubber oil in free fatty acids (20 to 26%), this filtered oil is mixed with glycerol already produced and heated to a suitable temperature in order to allow the free fatty acids to esterify glycerol. This operation reduces the free fatty acid content of rubber seed oil to less than 5%. Its purpose is to increase the yield of the subsequent transesterification. In a non-limiting embodiment, approximately 20 kg of glycerol are added to 400 kg of almond oil and the whole is heated using as a heat source the combustion of the shell resulting from the shelling of the seed;

- Transesterification: in an appropriate reactor, rubber oil reacts with ethanol in the presence of potassium hydroxide (KOH) as a catalyst at a suitable temperature to be transformed into methyl ester that can be used as biodiesel and into glycerol. In one embodiment, the reaction mixture may consist of approximately 420 kg of fat, 55 kg of ethanol, 5 kg of potassium hydroxide and 700 g of sulfuric acid. At the end of this operation, approximately 360 kg of methyl ester (biodiesel), 12 kg of soap and 50 kg of glycerol are collected separately.

The methyl ester that can be used as a component of biodiesel or totally as biodiesel for compatible engines is stored in the tanks after purification.

Claims (4)

1- Process for preparing a chemical composition from vegetable oil, characterized in that said process comprises a glycerolysis step which consists in esterifying glycerol using free fatty acids contained in said vegetable oil of structure triglyceride, extracted from rubber tree seed (Hevea brasiliensis), and a transesterification step which consists of heating to a suitable temperature, in the presence of ethanol, the mixture of vegetable oil with a triglyceride structure and esterified glycerol, under the action of a catalyst consisting of sodium hydroxide, to give a chemical composition usable as fuel or fuel composition. 2- Process according to claim 1, characterized in that the glycerolysis makes it possible to reduce the free fatty acid content of the vegetable oil in order to increase the yield of the transesterification reaction. 3- Process according to claims 1 and 2, characterized in that the chemical composition is btodiesel or a biodiesel composition. 4- Process according to the preceding claims, characterized in that the rubber seed oil is obtained at the end of the operations comprising: - hulling; - grinding; - the cooking ; - and extraction by pressing and by solvent.