Patent Application
20230002309
The present invention is related to nitrates of ethers of glycerol and ethanol as diesel cetane improvers, and the production process of the same. The invention proposed here aims at providing an additive produced from glycerol from the production of biodiesel and to bring to the additive market a more economical and efficient option to facilitate the ignition of diesel and improve the cetane number in said fuel.
Currently, environmental and legislative restrictions drive the development of biodiesel in the world. However, its production generates a series of by-products of low added value, among which it is possible to mention glycerin, which represents about 10% by weight of biodiesel production. Thus, for each ton of biodiesel produced, about 100 kg of glycerin are generated, which may vary according to the raw material used.
Considering that, in Brazil, Law No. 13,263/2016 determines a schedule for a progressive increase in the biodiesel content in diesel, from 8% in 2017 to 9% in 2018 and, finally, 10% in 2019, a great opportunity for the development of new applications to the surplus of glycerin generated is created.
From another point of view, more modern engines demand better quality fuels, which is reflected in the need for increasingly higher cetane numbers, since the progressive increase in this specification is directly linked to greater fuel economy, better cold start, lower emission of particulates and noise from the engine.
Among the various compounds used as cetane-improving additives, 2-ethyl hexyl nitrate (2-EHN) stands out. This compound, used all over the world, is produced from the nitration of 2-ethyl-hexanol (2-EH), a superior alcohol basically obtained from the hydroformylation of propene with synthesis gas (CO/H2). This raw material has a high cost and is also used in the production of plasticizers for polymers and esters.
In general, the companies producing 2-EHN dominate the entire production chain from the raw material to its distribution in the refineries. In Brazil, all the 2-EHN used to adapt the diesel to the specification of the Brazilian National Agency of Petroleum, Gas and Biofuels (ANP) is imported.
With respect to the universe of nitrates and their use as additives, it is important to highlight the document U.S. Pat. No. 2,294,849 that addresses to methods of preparing nitrates from various alcohols, aiming at using them as cetane improvers.
In the same context, patent GB 993623 points out the positive effect of nitrates of aliphatic alcohols of up to 5 carbon atoms in the increase of cetane in diesel compared to other nitrates of superior carbon chain. Likewise, U.S. Pat. No. 4,448,587 describes the synergistic effect of mixing aliphatic alcohol mono-nitrates with alcohol alkylated nitrates on increasing the cetane number in diesel.
Still in relation to additives, document PI 0803767-1 addresses to the production of glycerin ethers from the glycerin etherification reaction, under heterogeneous catalysis conditions, aiming at obtaining, with high selectivity, glycerol mono-ether, in particular glycerin tert-butyl ether. Said glycerol mono-ether is added to the fuel as an additive and the proposal is to obtain the additive from glycerin and tert-butanol. However, the document under analysis does not propose the nitration of the final additive.
Another document to be mentioned is PI 0505472-9, which addresses to a process and additive to increase the cetane number of the diesel. The additive is obtained from the reaction of an alkene or alkyne with glycerin, coming or not from the production of biodiesel. However, the process referring to document PI 0505472-9 does not dispense with the use of hydrocarbons for the production of the claimed additive.
From the mentioned documents, it appears that nitrated additives have superior performance with regard to the cetane number. Furthermore, the specialized literature SIRIPRAPAKIT et al., 2009, compares nitrated compounds with dinitrated compounds, showing the superiority of dinitrated compounds over nitrated ones, including against 2-ethyl hexyl nitrate, currently used in the market.
From the disclosure above, there is a need to obtain dinitrated compounds from glycerol, in order to optimize the properties of diesel and give a specific destination for the glycerol from the production of biodiesel.
The production process of nitrates from glycerol ethers and ethanol to be used as diesel cetane improvers uses reagents with a high supply on the market, namely glycerol and ethanol, according to the steps described below:
The addition of said glycerin and ethanol dinitrates to diesel allows to reach the specified cetane number using smaller amounts of additive when compared to the use of conventional additives.
The present invention will be described in more detail below, with reference to the attached figures that, in a schematic way and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:
The detailed description of the production process of the diesel cetane improver additive, from glycerol and ethanol, will be carried out according to the identification of the reagents and the steps of the obtaining process.
For a better understanding of the object of the present invention, diesel is considered to be a mixture of hydrocarbons, with a distillation range between 160° C. and 370° C. Glycerin is known by the traditional IUPAC nomenclature as propanetriol.
The present invention uses glycerin as a raw material for the synthesis of ethers that subsequently undergo a nitration process, according to the following steps:
In a first aspect, it should be highlighted that the compounds generated in step (a) are mono-ethers (1-ethoxy-2,3-propanediol; 2-ethoxy-1,3-propanediol), di-ethers (1,2-di-butoxy-3-propanol and 1,3-di-butoxy-2-propanol), and tri-ethers (tri-ethoxy-propane), as well as di-ethyl ether and water.
In a second aspect, it is highlighted that from step (b), a separation, a mixture of glycerol and ethanol mono-ethers is obtained, namely 1-ethoxy-2,3-propanediol and 2-ethoxy-1,3-propanediol, as well as a mixture of glycerol di- and tri-ethers and a di-ethyl ether stream.
In a third aspect, it is mentioned that the compounds resulting from step (d) are: 1-ethoxy-2,3-propadiol dinitrate and 2-ethoxy-1,3-propanediol dinitrate.
In a fourth aspect, it should be emphasized that the dinitrated ethers obtained in step (d) present unexpectedly superior results, as diesel cetane improvers, when compared to those obtained with 2-ethyl hexyl nitrate (2-EHN).
In a last aspect, the nitration process of glycerol and ethanol mono-ethers is processed in the reactor until the temperature stabilizes, indicating the end of the formation of a mixture of dinitrated ethers, in particular, 1-ethoxy-2,3-propanediol dinitrate or 2-ethoxy-1,3-propanediol dinitrate.
As can be seen in
A sample of S10 diesel (with up to 10 ppm sulfur), with a cetane number of 45.8, was used to evaluate the performance of various cetane-improving additives. The additives studied were: 2-ethyl hexyl nitrate (2-EHN), considered to be the standard for diesel additives; 1,2-di-butoxy-3-propanol nitrate; 1-butoxy-2,3-propanediol dinitrate; 1,2-propylene glycol dinitrate and 1-ethoxy-2,3-propanediol dinitrate. For each type of additive, several samples were prepared with concentrations of additive varying from 100 to 2100 ppm by weight. The cetane number of each sample was evaluated by the ASTM D6890 method (Ignition Quality Test—IQT) and the results are shown in
It is verified that the mono-ether of glycerol and ethanol nitrated in two positions (1-ethoxy-2,3-propanediol dinitrate) performed much better than 2-EHN (2-ethyl hexyl nitrate) for all concentrations tested.
With regard to 1,2-propylene glycol dinitrate, it is noted that it has lower performance than 1,2-di-butoxy-3-propanol nitrate, despite having two nitro groups. This fact suggests that the greater polarity of this dinitrate should negatively influence its miscibility in diesel and, consequently, its performance as an additive.
In relation to 1-butoxy-2,3-propanediol dinitrate, it presented results well superior to 1,2-propylene glycol dinitrate, approximating to 2-EHN (2-ethyl hexyl nitrate). Possibly, this result can be explained by the lower polarity of 1-butoxy-2,3-propanediol compared to 1,2-propylene glycol dinitrate, allowing greater miscibility in diesel.
This said, one would not expect a better result from 1-ethoxy-2,3-propanediol dinitrate than that obtained from 1-butoxy-2,3-propanediol dinitrate, as they both have two nitro groups and the first is more polar than the second. However, what is observed is a much superior result for 1-ethoxy-2,3-propanediol dinitrate, which is even higher than 2-EHN (2-ethyl hexyl nitrate).
In a second test, a sample of S10 diesel (up to 10 ppm of sulfur), of naphthenic base, with initial cetane number of 46.4, was used to compare the performance of 2-EHN (2-ethyl hexyl nitrate) and 1-ethoxy-2,3-propanediol dinitrate in different concentrations. The cetane number of each sample was evaluated by the ASTM D6890 method (Ignition Quality Test—IQT) and the results are shown in
From these analyses, it was possible to confirm a better performance of glycerol and ethanol mono-ether dinitrate when compared to 2-EHN (2-ethyl hexyl nitrate).
Thus, to obtain cetane number 48, specification of S10 cetane by the ANP (Brazilian National Agency of Petroleum, Gas and Biofuels), approximately 200 ppm of 2-EHN (2-ethyl hexyl nitrate) would be needed, whereas to achieve the same cetane number, under the same conditions, only 100 ppm of 1-ethoxy-2,3-propanediol dinitrate would be needed.
It should be noted that, although the present invention has been described in relation to the attached figures, it may undergo modifications and adaptations by technicians skilled on the subject, depending on the specific situation, but provided that it is within the inventive scope defined herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| BR10 2019 0251735 | Nov 2019 | BR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/BR2020/050488 | 11/19/2020 | WO |
