NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS AND THE PRODUCTION PROCESS OF THE SAME

Abstract

The present invention is related to the use of nitrates of ethers of glycerol and ethanol as diesel cetane improvers, and the production process of the same, aiming at producing an additive from glycerol from biodiesel production and bringing to the additive market an option more economical and efficient to facilitate the ignition of diesel and improve the cetane number of said fuel.

Claims

1- NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS, characterized in that they are produced by a process comprising the following steps: a) etherification reaction between glycerol and alcohols; b) separating the compounds obtained in step (a); c) nitration of glycerol and ethanol mono-ethers, separated in step (b), with the substitution of the two available hydroxyls, forming dinitrated ethers, wherein the additive obtained is 1-ethoxy-2,3 propanediol dinitrate or 2-ethoxy-1,3 propanediol dinitrate.

2- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that they use anhydrous or hydrated ethanol as raw material in their production.

3- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that they use glycerin from biodiesel production process plants as raw material in their production.

4- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that the etherification reaction is catalyzed by acidic catalysts, which can be chosen from: ion exchange resins, zeolites, aluminas, niobic acid or other acidic catalyst.

5- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that the etherification reaction is carried out in a batch reactor (STR), continuously fed (CSTR), fixed bed or reactive distillation.

6- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that the etherification reaction occurs with a glycerol/ethanol molar ratio ranging between 1:1 and 1:6, temperature between 50 and 250° C. and the space velocity (LHSV) from 0.25 to 4.00 h.sup.−1.

7- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that there are generated in step (a) 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.

8- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that in step (b) the following streams are separated: mixture of glycerol and ethanol mono-ethers, namely, 1-ethoxy-2,3-propanediol and 2-ethoxy-1,3-propanediol; mixture of glycerol di- and tri-ethers (1,3-di-ethoxy-2-propanol, 1,2-di-ethoxy-3-propanol and 1,2,3-tri-ethoxy-propane) and di-ethyl ether.

9- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that the nitration step of glycerol and ethanol mono-ethers occurs in a temperature range between −10° C. and 10° C.

10- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that the nitration step of glycerol and ethanol mono-ethers uses a sulfonitric mixture (sulfuric oleum or concentrated sulfuric acid and concentrated nitric acid) with or without the addition of a cosolvent (dichloromethane, preferably, but not limited to this), a mixture of nitric acid and acetic anhydride, in a ratio of 30:70 to 50:50, with an excess of up to 200%.

11- THE NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS according to claim 1, characterized in that, in the nitration step of the glycerol and ethanol mono-ethers (step (d)), there is the formation of a mixture of dinitrated ethers, specifically, 1-ethoxy-2,3-propanediol dinitrate or 2-ethoxy-1,3-propanediol dinitrate.

12- A PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL AS DIESEL CETANE IMPROVERS characterized in that it comprises the following steps: a) etherification reaction between glycerol and alcohols; b) separating the compounds obtained in step (a); c) nitration of glycerol and ethanol mono-ethers, with the substitution of the two available hydroxyls, forming dinitrated ethers, using glycerin from the biodiesel production process.

13- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that it uses ethanol and glycerol from the biodiesel reaction as reagents.

14- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that the etherification reaction is catalyzed by acidic catalysts that can be chosen from: ion exchange resins, zeolites, aluminas, niobic acid or another acidic catalyst.

15- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that the etherification reaction occurs with a glycerol/ethanol molar ratio ranging between 1:1 and 1:6, temperature between 50 and 250° C. and the space velocity (LHSV) from 0.25 to 4.00 h.sup.−1.

16- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that the etherification reaction is carried out in a batch reactor (STR), continuously fed (CSTR), fixed bed or reactive distillation.

17- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that mono-ethers, (1-ethoxy-2,3-propanediol) are generated in step (a), 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.

18- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that, during step (b), the following streams are separated: mixture of glycerol and ethanol mono-ethers, namely 1-ethoxy-2,3-propanediol and 2-ethoxy-1,3-propanediol; a mixture of glycerol di- and tri-ethers (1,3-di-ethoxy-2-propanol, 1,2-di-ethoxy-3-propanol and 1,2,3-tri-ethoxy-propane) and di-ethyl ether.

19- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that the nitration step of glycerol and ethanol mono-ethers occurs at temperatures in the range between −10° C. and 10° C.

20- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that the nitration step of the glycerol and ethanol mono-ethers uses a sulfonitric mixture (sulfuric oleum or concentrated sulfuric acid and concentrated nitric acid) with or without the addition of a cosolvent (dichloromethane, preferably, but not limited to this), mixture of nitric acid and acetic anhydride, in a ratio of 30:70 to 50:50, with an excess of up to 200%.

21- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that the nitration step of glycerol and ethanol mono-ethers occurs by direct reaction with dinitrogen pentoxide or nitronium chloride.

22- THE PROCESS FOR OBTAINING NITRATES OF ETHERS OF GLYCEROL AND ETHANOL according to claim 12, characterized in that, in the nitration step (step (d)) of glycerol and ethanol mono-ethers, occurs the formation of a mixture of dinitrated ethers, specifically, 1-ethoxy-2,3-propanediol dinitrate or 2-ethoxy-1,3-propanediol dinitrate.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0018] 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:

[0019] FIG. 1: a graph with results of tests carried out with the objective of evaluating the performance of different nitrates of glycerol ethers against 2-EHN (2-ethyl hexyl nitrate) in increasing the cetane number in S10 diesel (with up to 10 ppm sulfur).

[0020] FIG. 2: graph with the results of tests carried out with the objective of evaluating the influence of the concentration of the additives 1-ethoxy-2,3-propanediol dinitrate and EHN (2-ethyl hexyl nitrate) on the increase in the cetane number of the S10 diesel (with up to 10 ppm sulfur).

DETAILED DESCRIPTION OF THE INVENTION

[0021] 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.

[0022] 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.

[0023] 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: [0024] (a) etherification reaction of glycerin with ethanol, at a temperature between 50° C. and 250° C., in liquid phase. In this step, acidic catalysts can be used, chosen from: ion exchange resins, zeolites, aluminas, niobic acid or others. The reaction takes place in batch reactors (STR), continuously fed (CSTR) or in a fixed bed. Preferably, the glycerol/ethanol molar ratio ranges from 1:1 to 1:6 and the space velocity (LHSV) ranges from 0.25 to 4.00 h.sup.−1, depending on the catalytic system used. In this process, there are produced mono-ethers (1-ethoxy-2,3-propanediol, 2-ethoxy-1,3-propanediol), di-ethers (1,3-di-ethoxy-2-propanol, 1,2-di-ethoxy-3-propanol), tri-ethers (1,2,3-tri-ethoxy-propane), di-ethyl ether and water, with yields depending on the operating conditions used; [0025] (b) after the etherification reaction, the reactor effluent is separated by traditional unit operations, such as flash, decantation and distillation, in order to obtain the glycerol and ethanol mono-ethers in a concentrated form. The glycerol di- and tri-ethers produced can be sent to the diesel pool or to other applications such as solvents and bases for paints and cleaning products. The di-ethyl ether formed could also be used as a fuel or in more specific applications; [0026] (c) nitration of the glycerol and ethanol mono-ethers obtained in step (b). Nitration takes place at a temperature of −10 to 10° C., using a sulfonitric mixture (sulfuric oleum or concentrated sulfuric acid and concentrated nitric acid), with or without the addition of a cosolvent (dichloromethane, preferably, but not limited to this), a mixture of nitric acid and acetic anhydride, in a ratio of 30:70 to 50:50, with an excess of up to 200%. Alternatively, the nitration process can occur by means of the direct reaction with dinitrogen pentoxide (N.sub.2O.sub.5) or nitronium chloride; [0027] (d) dilution of the mixture from step (c) with ice water, followed by a neutralization reaction, in which the organic phase is subjected to neutralization to pH 6.0, with an alkaline solution, at a temperature close to 0° C. In this step, the co-solvents and residual acids are recovered, while the dinitrated ethers are stabilized and are then ready for use.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] 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.

[0033] As can be seen in FIGS. 1 and 2, the dinitrated glycerol and ethanol mono-ethers obtained in step (d) are compared with other nitrated additives used as diesel cetane number improvers. In these tests, it was observed that 1-ethoxy-2,3-propanediol dinitrate performed significantly better than 2-ethyl hexyl (2-EHN), the main commercial additive used.

EXAMPLE 01

[0034] 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 FIG. 1. It is observed that both glycerol tert-butyl ethers nitrated in one or two positions and 1,2-propylene glycol dinitrate showed lower performances than 2-ethyl hexyl nitrate (2-EHN).

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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).

EXAMPLE 02

[0039] 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 FIG. 2.

[0040] 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).

[0041] 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.

[0042] 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.