BRPI0902818A2 - Propylene glycol production process from biodiesel glycerine - Google Patents

Abstract

PROPYLENGLYCOL PRODUCTION PROCESS FROM BIODIESEL GLYCERIN. The present invention describes a process for the production of propylene glycol from glycerine generated during the biodiesel production process, the transformation of purified glycerin to propylene glycol carried out by means of a liquid phase hydrogenolysis reaction in two consecutive steps, however. in a single fixed bed reactor (1) under determined temperature and pressure conditions, whose effluent from the fixed bed reactor (1) is conducted to subsequent process steps comprising separation and purification.

Description

PROPYLENGLYCOL PRODUCTION PROCESS FROM BIODIESEL DEGLYCERIN

FIELD OF INVENTION

The present invention is in the field of processes for producing propylene glycol from glycerin. Specifically, the invention deals with the production of propylene glycol from glycerin resulting from the process of obtaining biodiesel.

BACKGROUND OF THE INVENTION

Currently, there is a significant increase in the supply of glycerin in the market, largely due to the worldwide expansion of biodiesel production. Within the biodiesel production process, agglicerin is a byproduct generated at a mass ratio of 10/1 (biodiesel / glycerin).

However, this excess supply of glycerin directly implies a drop in its commercial value making other applications viable.

Several studies have been started with the purpose of taking advantage of this glycerine excess by turning it into new products or employing glycerin as a raw material for the production of new products that have greater commercial value.

Technical publications on the subject are increasing as solutions for the utilization of this glycerine excess are designed.

One of the products of interest is propylene glycol and its production from glycerin.

RELATED TECHNIQUE

Within the state of the art that has been forming in this regard, some very exemplary documents on the development of related processes can be highlighted.

WO 2008/051540 A2 (Archer-Daniels-MidlandCompany) discloses a process for the production of propylene glycol from glycerin using a fluidized bed reactor operating at temperatures in the range of 178 ° C to 205 ° C, pressures in the range of 1200 psi to 1600 psi, with hydrogen / glycerine molar ratio in the range of 1: 1 to 10: 1 and a spatial velocity in the range of 0.5h "1 to 10h ~ 1. Reactor charge is a predominantly aqueous solution containing 30% by weight of glycerine in alkaline medium selected from metal hydroxides, alkoxides, basic salts and metal oxides.

WO 2007/053705 A2 (University of Missouri Board of Curators) discloses a process for producing a mixture of deacetol and propylene glycol in any proportion from glycerine in vapor phase. Glycerin partial pressure is in the range 0.01 bar to 0.5 bar and the temperature in the range 80 ° C to 300 ° C. The partial pressure of hydrogen within the process is in the range 0.01 bar to 25 bar. A heterogeneous catalyst is used which has at least one element of group I or Vlll of the periodic table, ruthenium, copper, or even a combination of these elements.

US 2005/0244312 and Pl 0507874-1 (Galen J.Suppes, William Rusty Sutterlin and Mohanprasad Dasari) present processes for producing acetol, propylene glycol or a mixture of glycerine and propylene glycol, primarily used as an antifreeze fluid, from glycerin as a raw material. For the production of propylene glycol, the emphasis is on a two-step process in which the first step is acetyl production by reactive distillation where glycerin is dehydrated to acetol with the aid of a catalyst, which is immediately distilled from the reaction medium with the aid of a catalyst. In this first stage, batch or semi-batch reactors are used, temperature in the range of 170 ° C to 270 ° C, pressure in the range 0.2 bar to 25 bar, the glycerin Dakar should contain a range of 0% to 15% by volume. water mass, with a heterogeneous catalyst which may have an element chosen from palladium, nickel, rhodium, chromium, copper or a combination thereof, preferably a catalyst based on a combination of copper and chromium. In a second step, the acetol produced, when mixed with hydrogen, undergoes hydrogenation to propylene glycol with decatalyst aid. In this second step the reaction time is in the range of 0 to 24 hours, the temperatures are in the range of 50 ° C to 250 ° C, preferably 150 ° C to 220 ° C, pressure between 1 bar and 25 bar, preferably between 10 bar and 20 bar, the acetol filler contains, at most, 50% by weight of water, preferably between 0% and 35%, as a common catalyst which may be chosen in the same manner as the catalyst chosen for the first step, with a preferred catalyst being preferred. in a combination of copper and chrome.

WO 2008/049470 A1 (Clariant International Ltd.) discloses an autoclave process for the production of propylene glycol from glycerine, where glycerine must have at least 95% purity under hydrogen pressure in the range of 20 bar to 100 bar, temperature in the range 180 ° C to 240 ° C and in the presence of a catalyst comprising 20% to 0% copper oxide, 30% to 70% zinc oxide and 1% to 10% manganese oxide.

WO 2007/010299 (Davy Process Technology Ltd.) discloses a process of producing propylene glycol from glycerine, carried out in a vapor phase in the presence of a copper base catalyst. The process temperature is in the range between 160 ° C and 260 ° C and the pressure in the range between 10 bar and 30 bar. The relationship between hydrogen and glycerin is in the range between 400: 1 and 600: 1 with spatial velocity between 0.01 h "1 and 2.5 h" 1.

WO 2008/012244 (Davy Process Technology Ltd.) discloses process modifications of the above document by adding various stages to the process emphasizing the reduction in the amount of hydrogen required by the process when operated under this stage regime.

WO 03/035582 (Battelle Memorial Institute & MichiganState (Jniversity)) discloses a sugar hydrogenolysis process containing six carbon atoms and polyols, including glycerin, using a rhenium-containing multimetal solid catalyst. The process is conducted under temperature in the range. 120 ° C to 250 ° C, the common pH value of the liquid charge in the range 8 to 13 and a hydrogen pressure during the glycerine hydrogenolysis reaction in the range 600 psi to 1800 psi.

WO 2008/133939 (Archer-Daniels-Midland Company) discloses a glycerine catalytic hydrogenolysis process where the spatial velocity of the charge is in the range of 0.5 h-1 to 2.5 h-1. a solution containing between 25% and 40% USP1 alkaline glycerine alkalized with sodium or potassium hydroxide or alkoxide such that a pH value in the range 6 to 14 is obtained. Hydrogen pressure is in the range 500 psi to 2000 psi, at a temperature in the range between 150 ° C and 300 ° C and a molarhydrogen / glycerine ratio in the range between 1: 1 and 10: 1. The document highlights that, besides producing propylene glycol as a major compound, there is the formation of butanediols and a proportion of other diols in the range 0.04% to 2.31% The product purification / separation section proposed in this process comprises a step of removal of the alkalizing agent by means of an ion exchange resin and by distillation steps of the products. P first distillation tower, water and light alcohols are removed from the top and sent to a second distillation tower for separation. The bottom effluent from the first distillation tower proceeds to a plurality of small distillation towers in which waste water and unconverted glycerin are separated. The propylene glycol enriched stream is conducted to a distillation tower for separation from other byproducts, mainly ethylene glycol. WO 2008/057317 (Archer-Daniels-Midland Company) discloses a process for purifying propylene glycol and ethylene glycol produced from a renewable source. The process employs a polar solvent to aid in the distillation separation of the components.

A mixture of polyols produced during a hydrogenolysis reaction of a renewable raw material, among many glycerin, is mixed with a polar solvent such as water, methanol, ethanol, n-propanol, n-butanol, i-butanol, amyl alcohol, acetone, butyric acid, gluconic acid, acetic acid, lactic acid, sulfuric acid and hydrochloric acid, so that it does not form azeotrope with the components of the mixture for distillation.

This type of distillation is known as extractive distillation and is used when the components of a mixture have low relative volatility. The polar solvent interacts differently with the components of the mixture causing a change in volatility relative to these components and thus enables the separation to be accomplished.

UOP has been publicizing a process of transformation of glycerine to propylene glycol in a single stage using a catalyst whose composition has not been disclosed. The process selectivity reported is 90 wt% propylene glycol in 79 wt% yield. The byproduct formed in higher content is ethylene glycol, around 3% by weight in the reactor effluent which is subsequently separated from the medium. The propylene glycol produced has a purity of 99.5% w / w. A glycerine of 40% by weight purity may be used as a filler, and the purification step may be dispensed with, depending on the initial filler characteristic. Taltechnology is ready to be licensed.

As has been observed, the studies are progressing, although, among the processes cited above, there is very little concern with the product separation stage. The present invention provides an alternative route for obtaining propylene glycol, with process optimization as a whole, as well as recovery, separation and final treatment of the obtained products.

SUMMARY OF THE INVENTION

It is an object of the present invention, a process for the production of glycine depropylene glycol, in which reactions occur in faseliquid and glycerin is employed as a feedstock is specifically that generated during the process of obtaining biodiesel.

Biodiesel glycerine or blonde glycerine is produced with a purity in the range of 40% to 85% and, to be used as a raw material for the production of propylene glycol according to the present invention, needs to be purified by purification processes normally employed in the art. yielding a glycerine with a purity content in the range of 90% to 99% by weight.

The transformation of purified glycerin to propylene glycol is carried out by means of a hydrogenolysis reaction which is conducted in a liquid phase, where the two reaction steps occur simultaneously and in the same reactor.

In the first stage the glycerol by temperature effect and catalyst is transformed into acetol and water. In the second stage acetol, by decatalyst effect and hydrogen gas is transformed into propylene glycol.

The reactor effluent is conducted to a separation section and purification after which a high purity, low contaminant end product is obtained.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a representation of the illustrative chemical equations of the transformation of glycerine from biodiesel to propylene glycol.

Figure 2 is a simplified flowchart representation of the glycerine to propylene glycol hydrogenolysis process.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process for the production of glycine depropylene glycol, in which reactions take place in faseliquid and glycerine is specifically generated during the process of obtaining biodiesel. Glycerin produced throughout the biodiesel production process, which is used as the process raw material of the present invention, initially has a purity range of between 40% and 85% due to the presence of numerous daring by-products, such as:

- salts containing sodium, chlorine, sulfur and phosphorus which irreversibly deactivate the catalyst;

- fatty acids, phospholipids, glycerides, soaps and biodiesel residues which deactivate the catalyst by pore blocking. Propylene glycol production has as its raw material staglycerin, after purified it is transformed into propylene glycol by means of a hydrogenolysis reaction, which and conducted in a liquid phase, where two reaction steps occur simultaneously and in a mesoreactor, that is, the glycerol by effect of temperature and catalyst is transformed into acetol and water and then by catalyst effect eg hydrogen is transformed into propylene glycol. The chemical reactions involved in the process are shown in Figure 1.

The process for producing propylene glycol from glycerine derived from biodiesel according to the present invention can be accompanied with the aid of Figure 2 and basically comprises the following steps:

(a) subject glycerine from a biodiesel (G) production and impurities by a purification step (P) to remove impurities (R) by a state-of-the-art purification process provided that this process provides a blond glycerine with purity in the range 90 to 99.9% by weight;

b) in a fixed bed adiabatic reactor operating in a downward flow regime in a liquid phase, carry out the hydrogenolysis reaction, where the two reaction steps occur simultaneously as follows:

■ activate a copper chromite catalyst by hydrogen pass through;

■ pressurizing the fixed bed reactor (1) to a pressure which may be in a range of 5 to 40 bar, preferably between 15 and 30 bar;

■ raise the catalytic bed temperature to an operating temperature in the range of 180 ° C to 260 ° C;

■ initiate intake of purified glycerin with a certain water content from a loading line (12) and initiate hydrogen intake from a gas line (13), with a molar ratio of glycerine to hydrogen in the range 1/3 to 1/50 a spatial velocity in the range 0.1 h "1 to 4.0 h" 1 relative to the limiting reagent (glycerin);

c) cooling and withdrawing the effluent preferably through the bottom of the reactor and conducting through a reaction line (11);

d) the effluent from the fixed bed reactor (1) via the reacted line (11) is cooled and enters a flash separator vessel (2) for removal of a hydrogen-containing stream and light noncondensible compounds by a first detopic stream (21) and removing liquid effluent through a first bottom stream (22);

e) the first top stream (21) from the deflash separator vessel (2) enters a recycle compressor (3), which compresses the content of this stream where part is driven by a first recycle line (31) to the reactor (1). ) of a fixed bed, while the other part is conducted by a first purge line destined for incineration burning (32), f) the liquid effluent from the first bottom stream (22) from the flash separator vessel (2) enters a primary fractionation tower (4), which discharges through a top second stream (41) water and polar light compounds such as methanol, ethanol, n-propanol and isopropanol, while the deep effluent is driven by a second bottom stream (42);

g) the bottom effluent from the second bottom stream (42) from the primary fractionation tower (4) enters a heavy duty removal tower (5), which removes unreacted glycerin and other heavy products formed during the hydrogenolysis reaction, which are driven by a third bottom stream (52) to destinations which may be chosen from: a second firing line (53) for incineration and power generation and a second recycling line (54) where glycerin is returned to the bed reactor (1) fixed while by the third topcurrent (51) propylene glycol with impurities is conducted;

h) the effluent from the third top stream (51) from the heavy duty removal stream (5) enters a purification tower (6), which removes impurities such as ethylene glycol, 1,3-propylene glycol and a small content of heavy compounds; which are led by a fourth bottom stream (62) to the junction with the second firing line (53) for incineration and power generation, while high purity propylene glycol is obtained by the fourth top stream (61).

Due to the exothermicity of the reactions involved, the fixed reactor (1) may contain more than one catalytic bed and have a cooling system between the beds. Propylene glycol produced according to the present invention has an estimated purity of over 99% with low contaminant content.

The following is a merely illustrative example of the application of the process object of the present invention.

After in situ activation of the catalyst via hydrogen passage, the system was pressurized to approximately 20 bar with hydrogen and the operating temperature set to 220 ° C. Admitted purified glycerin containing a certain water and hydrogen content at a 1/35 molar glycerine / hydrogen ratio with a 1 h ~ 1 spatial velocity to the limiting reagent (glycerin). The fixed bed reactor (1) operated isothermally. The reactor effluent (1) after analysis had a glycerine conversion greater than 99% and the propylene glycol selectivity was 88.6%.

The complete reactor effluent composition of this example is listed in table 1 below:

TABLE 1

<table> table see original document page 11 </column> </row> <table>

Although the present invention has been described in its preferred embodiment, the main concept underlying the present invention which is a process for producing propylene glycol from glycerin, particularly from biodiesel glycerin, remains preserved as to its innovative character, wherein those of ordinary skill in the art may envision and practice variations, modifications, alterations, adaptations and equivalents, as appropriate and compatible with the working environment in question, without, however, departing from the scope and spirit of the present invention, which are represented by the following claims.

Claims (4)

1. - PROPYLENGLYCOL PRODUCTION PROCESS FROM BIODIESEL DEGLYCERIN, characterized in that the glycerine used as raw material comes specifically from a biodiesel production process, the purity of which is in the range of 90% to -99.9% by weight. (a) in a fixed-bed adiabatic downflow reactor operating in a liquid phase, carry out the hydrogenolysis reaction, where the two reaction steps occur simultaneously; from the bottom of this reactor (1) and lead through a line of reactant (11), c) the effluent from the fixed bed reactor (1) by means of the reaction line (11) is cooled and into a deflash separator vessel (2) for removing a hydrogen-containing stream and light noncondensable compounds by a first first stream (21) and removing liquid effluent by a first bottom stream (22); d) the first top stream (21) comes from Before the deflash separator vessel (2) enters a recycle compressor (3), which compresses the content of this stream where part is driven by a first recycle line (31) to the fixed bed reactor (1), while another part is driven by a first purge line intended for incineration burning (32) e) the liquid effluent from the first bottom stream (22) from the flash separator vessel (2) enters a primary fractionation tower (4), which discharges by a second stream of (41) water and polar light compounds such as methanol, ethanol, n-propanol and isopropanol, while the deep effluent is driven by a second bottom stream (42); f) the second bottom stream (42) bottom effluent from the primary fractionation tower (4) enters a heavy duty removal tower (5), which removes unreacted glycerin and other heavy products formed during the hydrogenolysis reaction, which are driven by a third bottom stream (52) to destinations can be chosen from: a second firing line (53) for incineration and power generation and a second recycling line (54) where glycerin is returned to the fixed bed reactor (1) while by the top third current (51) propylene glycol with impurities is conducted; g) the effluent from the third top stream (51) from the heavy duty removal stream (5) enters a purification tower (6), which removes impurities such as ethylene glycol, 1,3-propylene glycol a small content of heavy compounds which are led by a fourth bottom stream (62) to the junction with the second firing line (53) for incineration and power generation, while high purity propylene glycol is obtained by the fourth top stream ( 61). 2. The production process of propylene glycol from dehydroglycerin according to claim 1, characterized in that the fixed bed reactor (1) can contain more than one catalytic bed and has a cooling system between the beds due to the exothermicity of the reactions. involved. 3 A process for the production of propylene glycol from dehydroglycerin according to claim 1, characterized in that the hydrogenolysis reaction is conducted using a copper chromite catalyst under the pressure of hydrogen in the range of 15 bar to 30 bar. 180 ° C and 260 ° C, with a molar ratio of glycerine to hydrogen in the range 1/3 to 1/50 and a spatial velocity in the range 0.1 h "to 4.0 h" 1 to to the limiting reagent (glycerin).