BRPI0905176B1 - PROCESS OF PRODUCING A CATALYST AND ITS USE FOR ACROLEIN AND LOW MOLECULAR WEIGHT ALDEIDS FROM GLYCERIN - Google Patents

Abstract

A process for producing a catalyst and its use for obtaining acrolein and low molecular weight aldehydes from glycerine The invention relates to a process for producing acrolein and low molecular weight aldehydes from glycerine, to maximize the production of acrolein and low molecular weight aldehydes by means of a glycerine dehydration process, whether or not derived from a biodiesel production process, in gas phase and in an alumina-based fixed catalyst reactor or fluorine-treated alumina base under specific operating conditions.

Description

(54) Title: PROCESS OF PRODUCTION OF A CATALYST AND ITS USE FOR OBTAINING ACROLEIN AND LOW MOLECULAR WEIGHT FROM GLYCERIN (51) Int.CI .: B01J 20/08; B01J 4/21; C07C 45/52; C07C 47/22 (73) Holder (s): PETRÓLEO BRASILEIRO S.A.- PETROBRÁS (72) Inventor (s): ANTONIO MANZOLILLO SANSEVERINO; JOÃO GUILHERME ROCHA POÇO; DAVID AUGUSTO DE FREITAS; ELIEZER LADEIA GOMES

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PROCESS OF PRODUCTION OF A CATALYST AND ITS USE FOR

OBTAINING ACROLEIN AND LOW MOLECULAR WEIGHT ALDEHYDES FROM GLYCERIN

FIELD OF THE INVENTION

The present invention finds its field of application among the processes of production of acrolein and low molecular weight aldehydes from glycerin. The proposed invention preferably uses glycerin from a biodiesel production process, aiming to maximize the production of acrolein and low molecular weight aldehydes through a process of glycerin dehydration, in gas and in a catalyst fixed bed reactor. based on modified alumina. BACKGROUND OF THE INVENTION

Acrolein is used in processes for the production of allyl alcohol, pyridine, beta-picolines, acrylic acid, acrylonitrile, methionine and 1,3propanediol.

A process of production of acrolein well known in the prior art occurs through the oxidation of propene.

The production of biodiesel from the transesterification of vegetable oils generates glycerin as a co-product, in a proportion of approximately 100 kg of glycerin for every 1000 kg of biodiesel. The worldwide increase in biodiesel production has led to a much greater supply of glycerin in the market than the demand.

The glycerin generated in a biodiesel production process contains a plurality of impurities, such as water, soaps, bases and salts. In this way, several alternatives for the use of glycerin are being studied, taking into account the particularities of the glycerin obtained by the referred biodiesel production process.

The acrolein production process by means of dehydration of glycerin, using acid as a catalyst, is a

2/11 a process known since before the 1920s. Initially, the processes best known in the state of the art had field of application on a laboratory scale.

Since then, great efforts have been made to increase acrolein production processes in terms of acrolein yield and scale, enabling an industrial application.

Acrolein production processes from glycerin have become viable alternatives for the use of this glycerin generated with biodiesel.

In general, one of the disadvantages of processes for the production of acrolein from glycerin consists in the formation of byproducts with inadequate selectivity, notably low molecular weight aldehydes and acetol (2-hydroxy-propanone).

Thus, a process for the production of acrolein from glycerin, where it is possible to prioritize selectivity for the production of a given product is something not yet well known in the state of the art.

RELATED TECHNIQUE

There are several patent documents in the state of the art that claim processes for obtaining acrolein.

These processes have many disadvantages for industrial applications, namely: low yields, high corrosivity, long reaction times, batch operation, catalyst formulations poorly suited in terms of activity, operating time and decommissioning. In addition, these catalytic systems are difficult to regenerate.

US patent 5,387,720 (Armin Neher et al.), Inserted here as a reference, discloses a process for obtaining acrolein through glycerin dehydration, using catalysts more suitable for an industrial application such as

3/11 example, ZSM-5 and Y zeolites, alpha-alumina with phosphoric acid, clays and other solid acids. Dehydration of glycerin solutions in water takes place in a gas phase in a temperature range between 250 ° C and 350 ° C, or in a liquid phase in a temperature range between 180 ° C and 350 ° C. The concentration of glycerin in water is between 10% and 40% w / w. The catalysts have an optimal range of acidity, defined by the acid function of Hammet: -8.2 <H _O <+2.

The best reported acrolein yield is 70.5%, with 100% conversion of glycerin, in a reaction conducted in a vapor phase with the gamma-alumina catalyst impregnated with phosphoric acid and an inlet concentration of aqueous glycerin solution equal to 20% w / w. Hydroxypropanone was formed with 10% yield. For a load with a concentration of 40% w / w, for example, the yields are lower.

The liquid phase reaction was carried out at a pressure of 70 atm, which is a disadvantage compared to the gas phase reaction. Conversions were low, in a range of values between 8% and 16%, and the best reported selectivity of acrolein is 75%.

In processes where high pressures and temperatures are involved, special metallurgy is required for the reactors used in the process, which considerably increases the process costs and, consequently, the final cost of the products obtained.

Patent application JP 2008088149 (Tomoji et al.), Inserted here as a reference, protects the use of heteropoly acids for dehydration of glycerin. Significant results were obtained for glycerin selectivity.

Despite the high selectivity, heteropoly acids are complex materials, whose syntheses require special conditions and consumption of various raw materials. In addition, heteropoly acids have low

4/11 thermal stability when compared with other traditional heterogeneous catalysts. Thus, the deactivation of the catalyst by the formation of coke becomes critical, since the heteropoly acids are not stable at temperatures commonly used for regeneration of the deactivated catalyst.

The international patent application WO 08/052993 (Paul OOonnor and others), inserted here as reference, claims a process for obtaining acrolein, through dehydration of glycerin in a circulating fluidized bed reactor, with solid acid catalysts based on zeolites . The process claimed in said patent has not very high yields, due to the formation of coke and various hydrocarbons.

It is important to note that the analyzed inventions do not take into account the possibility of an acrolein production process, with high selectivity for a wide range of glycerin concentration. Furthermore, the feasibility of a process with more simplified, safe and optimized industrial production conditions is not considered, such as, for example, lower reaction time, lower consumption of raw materials, softer pressure conditions, suitability of the catalysts in terms of activity, operating time and ease of regeneration.

SUMMARY OF THE INVENTION

The present invention deals with a process for the production of acrolein and low molecular weight aldehydes from glycerin, through the use of a modified alumina-based catalyst, eventually treated with fluorine, in order to maximize its selectivity for acrolein or for low molecular weight aldehydes.

The process, object of the invention, aims to maximize the production of acrolein and low molecular weight aldehydes using mild production conditions, lower consumption of raw materials, simplified metallurgy for the equipment involved and ease of regeneration

5/11 catalyst.

In addition, this process makes it possible to employ a wide range of aqueous glycerin solution concentration, as well as the use of glycerin from a biodiesel production process.

Thus, the objective is to maximize the production of acrolein and low molecular weight aldehydes through the dehydration of glycerin in the gas phase, in a catalyst fixed bed reactor based on alumina or based on fluorine-treated alumina. Thus, with the use of alumina or fluorine-treated alumina catalysts under specific operating conditions, one can maximize selectivity for acrolein or low molecular weight aldehydes.

BRIEF DESCRIPTION OF THE FIGURE

The characteristics of the production process of acrolein and low molecular weight aldehydes from glycerin, object of the present invention, will be better perceived from the detailed description that will be made below, by way of example only, associated with the drawing referenced below , which is an integral part of this report.

Figure 1 shows a schematic representation of some equipment involved in the process for the production of acrolein and low molecular weight aldehydes.

DETAILED DESCRIPTION OF THE INVENTION

The description of the production process of acrolein and low molecular weight aldehydes from glycerin, object of the present invention, will be made based on the figure, according to the identification of the respective components.

Figure 1 shows a schematic representation of the process for the production of acrolein and low molecular weight aldehydes according to the present invention, whose advantage is due to the fact that the dehydration of the glycerin charge occurs in the gas phase in a fixed bed reactor, as will be described below.

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An aqueous solution of glycerin (1) is mixed with a stream of gaseous nitrogen (2), forming an N ₂ / glycerin mixture (3) which is sent to a vaporization equipment (4). The vaporized N ₂ / glycerin mixture (5) goes to a catalyst fixed bed reactor (6), where the reaction products (7) are generated. The reaction products (7) are sent to a condenser (8) to separate the obtained condensation products (9). Optionally, the reaction products (7) can be sent to a measurement and control system (10) for data acquisition and analysis of the obtained compositions.

Alternatively, the condensation products (9) can also be sent to a measurement and control system (10) for data acquisition and analysis of the obtained compositions.

An alumina-based catalyst is used to maximize the production of acrolein. To maximize both the production of acrolein and the production of low molecular weight aldehydes, a fluorine-treated alumina-based catalyst can be used.

The glycerin-containing filler can be a composition with a concentration of glycerin preferably comprised in a range of values between 20% and 80% w / w. Alternatively, the glycerin-containing filler can be 100% pure glycerin. Preferably the cargo containing glycerin may come from a biodiesel production process. However, glycerin fillers from other sources can be used.

The operating temperature of the catalyst fixed bed reactor is between 320 ° C and 480 ° C.

The spatial speed is comprised in a range of values between 0.375 h ' ¹ and 1.5 h' ¹ .

EXAMPLES

The following non-limiting example serves to illustrate each step in the production process of acrolein and low molecular weight aldehydes a

7/11 starting from glycerin, the preparation of the catalysts and the results obtained. Example 1: Obtaining process

In order to assess the selectivity of acrolein and low molecular weight aldehydes, a small reaction system was set up and the catalysts were prepared, carrying out the experiments as described below:

An aqueous solution of glycerin, with a concentration comprised in a range of values between 20% and 80% w / w, was fed to the system through a metering pump. Nitrogen (N ₂ ) from storage tanks was mixed with the aqueous solution of glycerin. A N ₂ / glycerin mixture, in a known proportion, was sent to a vaporizer, and then to a commercially found catalyst fixed bed reactor of the Haber-Bosh type. The said catalyst fixed bed reactor, filled with known mass and volume of catalyst, was fed with the vaporized N ₂ / glycerin mixture, generating the reaction products. These reaction products were sent, under controlled flow, to a chromatograph. Periodic sampling of the produced liquid phase provided material for analysis. The chromatograph was coupled to a data acquisition system that provides the sampling compositions.

The catalyst fixed bed reactor used carries a load of up to 10 grams of catalyst. The tests were conducted according to the following conditions: the operating temperature of the fixed bed reactor comprised in a range of values between 320 ° C and 480 ° C; the flow of glycerin in a range between 0.18 ml / min and 0.72 ml / min and the spatial speed in a range between 0.375 h ' ¹ and 1.5 h ¹

Example 2: Preparation of the catalyst

An alumina-based catalyst was agglomerated with colloidal silica in order to obtain a catalyst / silica ratio of 60:40 by mass. O

8/11 particle diameter for use in the reactor was defined as 0.59 <Φ _Ρ <1.0 mm (28 to 16 Tyler). In a typical agglomeration, solid catalyst was added to the calculated amount of colloidal silica (31.5% w / w), at room temperature in a 150 ml becher. The addition of colloidal silica generated a mixture with a pH equal to 10.

The pH of the suspension was adjusted to 5 using nitric acid or ammonium hydroxide (1 Μ). The temperature was raised to 70 ° C, keeping the mixture stirred for 12 hours.

The pasty mixture obtained was dried in a porcelain crucible in an oven at 110 ° C for 12 hours. After drying, the sample was ground and sieved. The material obtained within the desired range of diameters was subjected to calcination in dry air at 350 ° C for 12 hours. After this stage, the particles were milled and classified and stored in a desiccator.

Example 3: Evaluation of results

Table 1 shows the selectivity as a function of temperature for acrolein and other products obtained, for example: acetaldehyde, propionaldehyde and hydroxypropanone, using alumina as a catalyst.

TABLE 1 Temperature (° C) Product Selectivity (%) for glycerin concentration 20% w / w 40% m / m 80% m / m 380 Acrolein 2 to 60 26 to 70 50 to 78 Acetaldehyde 10 to 20 9a 11 7a9 Propionaldehyde 12 to 30 9 to 22 8 to 14 Hydroxypropanone 0a4 1 to 13 10a 15 450 Acrolein 47 to 62 - 8 to 65 Acetaldehyde 20 to 23 - 5th 19 Propionaldehyde 8 to 28 - 12 to 20 Hydroxypropanone 3 to 7 - 0a7

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The spatial speed varied in a range of values between 0.375 h ' ¹ and 1.5 h' ¹ .

Significant results were obtained, in terms of selectivity for acrolein, for aqueous glycerin solutions with concentration ranges between 40% and 80% w / w. For example, for an operating temperature of 380 ° C and a spatial speed of 1.5 h ¹ , a selectivity of 78% for acrolein was obtained, with 100% conversion of glycerin using an aqueous solution of glycerin with a concentration 80% w / w.

For a fluorine-treated alumina-based catalyst, the alumina was initially calcined at 500 ° C. 3.56 grams of ammonium fluoride (NH ₄ F, corresponding to 25 mL of 16.77% solution, pH = 11) were taken, diluted in 65 mL of water. To this solution, 130 grams of dry alumina (impregnation) were added and homogenized as much as possible. The solid went to the oven at 100 ° C for 17 hours. After this step, a new calcination was carried out at 540 ° C for 3 hours to guarantee the final reaction between alumina and NH ₄ F. The molar ratio AI: F was 100: 5. After agglomeration and sieving, the catalyst obtained was calcined in dry air at 350 ° C for 12 hours. After calcination, the particles were milled and classified and stored in a desiccator.

Table 2 shows the selectivity as a function of temperature for acrolein and other products obtained, for example, acetaldehyde, propionaldehyde and hydroxypropanone, using fluorine-treated alumina as a catalyst. The spatial speed varied in a range of values between 0.375 h ' ¹ and 1.5 h' ¹ .

Significant results were obtained, in terms of selectivity for acrolein, for aqueous glycerin solutions with concentration ranges between 40% and 80% w / w. For example, for an operating temperature of 350 ° C and a spatial speed of 1.5 h ' ¹ , a selectivity of 80% for acrolein was obtained, with 100% of

10/11 conversion of glycerin using an aqueous solution of glycerin with a concentration of 40% w / w.

TABLE 2 Temperature (° C) Product Selectivity (%) for glycerin concentration 20% w / w 40% m / m 80% m / m 350 Acrolein 2 to 70 50 to 80 32 to 72 Acetaldehyde 9 to 26 2a 13 2a8 Propionaldehyde 12 to 38 6 to 23 2a 11 Hydroxypropanone 2a8 5th 11 10a 13 385 Acrolein 45 to 72 3 to 69 - Acetaldehyde 10 to 18 3a 11 - Propionaldehyde 11 to 31 4 to 17 - Hydroxypropanone 5a7 0 to 10 - 450 Acrolein 27 to 48 3 to 54 - Acetaldehyde 26 to 28 22 to 32 - Propionaldehyde 20 to 46 22 to 50 - Hydroxypropanone 0 0

The use of alumina catalyst treated with fluoride also provided a significant result with regard to the selective production of ethanaldehyde and propionaldehyde. Comparing the results for the alumina catalyst and for the fluorine-treated alumina catalyst, it can be concluded that the presence of fluorine causes an increase in selectivity for ethanaldehyde and propionaldehyde. At an operating temperature of 450 ° C, a spatial speed of 0.375 h ' ¹ and a concentration of 40% w / w aqueous glycerin solution, a selectivity of 50% propionaldehyde, 32% ethanaldehyde and 10% acrolein. The mixture of these three products is easily separated by distillation.

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The description that has been made so far of the production process of crolein and low molecular weight aldehydes from glycerin, object of the present invention, should be considered only as a possible or possible embodiments, and any particular characteristics introduced therein should be understood only as something that has been described to facilitate understanding. Thus, they cannot in any way be considered as limiting the invention, which is limited to the scope of the following claims.

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Claims (5)

1- PROCESS OF PRODUCTION OF A CATALYST FOR OBTAINING ACROLEIN AND LOW MOLECULAR WEIGHT FROM GLYCERIN, characterized by comprising a catalyst based on alumina agglomerated with colloidal silica in order to obtain a catalyst / silica ratio of 60:40 in mass and average particle diameter selected for use in the reactor between 0.59 <Φ _Ρ <1.0 mm. 2- PROCESS OF PRODUCTION OF A CATALYST FOR OBTAINING ACROLEIN AND LOW MOLECULAR WEIGHT FROM GLYCERIN, according to claim 1, characterized by comprising an alumina-based catalyst that can be treated with fluorine, to obtain a molar ratio AI: F of 100: 5. 3- PROCESS OF PRODUCTION OF A CATALYST FOR OBTAINING ACROLEIN AND LOW MOLECULAR WEIGHT FROM GLYCERIN, according to claim 1, characterized in that said catalyst has high selectivity for acrolein and for low molecular weight aldehydes. 4- PROCESS OF PRODUCTION OF ACROLEIN AND LOW MOLECULAR WEIGHT ALDEHYDES FROM GLYCERIN, by means of dehydration of glycerin in the gas phase and in the presence of an alumina-based catalyst obtained according to claims 1 and 2, characterized by a load containing between 20% and 80% w / w of glycerin be sent to a fixed bed reactor filled with the said alumina-based catalyst, maintained at a temperature between 320 ° C and 480 ° C and space speed in a range of values between 0.375 h ¹ and 1.5 h ' ¹ , where dehydration of glycerin occurs and the formation of low molecular weight aldehydes in the gas phase. 2/2 5- PROCESS OF PRODUCTION OF ACROLEIN AND LOW MOLECULAR WEIGHT ALDEHYDES FROM GLYCERIN, according to claim 4, characterized in that the load containing glycerin can be selected from glycerin from a process of 5 production of biodiesel and glycerin 100% pure. 1/1