MXPA97004211A - Method for the elaboration hydroximethylphurfural apparate from aldohex - Google Patents

Abstract

The invention relates to a method for making hydroxymethylfurfural from a liquid medium containing at least one aldohexose or a saccharide capable of releasing at least one aldohexose, wherein the liquid is heated to a temperature greater than 100 ° C, in the simultaneous presence of two different acid catalysts. The first catalyst consists of an aluminosilicate in protonic form having a Si / Al ratio of less than 4, while the second is an aluminosilicate in protonic form having a Si / Al ratio higher than

Description

METHOD FOR THE ELABORATION OF HYDROXYMETHYLPHFROPHAL FROM ALDOHEXOSE FIELD OF THE INVENTION The present invention relates to a process for the manufacture of 2-carboxaldehyde-5-hydroxymethyl furfural, more commonly referred to as hydroxymethylfurfural (HMF), from a liquid medium, containing at least one aldohexose or an osido to release, at least, an aldohexose.

BACKGROUND OF THE INVENTION The HMF can be manufactured in an organic medium (FR-A-2 669 635) or in an aqueous medium (WO-A-92/10486), from fructose or polyfructans. The synthesis of HMF can be carried out by heating said medium, in the presence of a heterogeneous acid catalyst. Although the synthesis from ketohexoses is quite satisfactory, the transformation of the aldohexose, in particular of the glucose, under the conditions described by the prior art is insignificant in practice. However, sugar solutions available on the market at lower cost, sometimes contain ósidos such as sucrose, inulin or starch that release at least one aldohexose by hydrolysis; or inverted sugars obtained by hydrolysis of these osides, in the form of a mixture of simple sugars with a high content of aldohexose (s). Therefore, the known processes need to carry out a preliminary or subsequent separation of the non-transformed sugars, in particular of aldohexoses such as glucose. In order to reduce the drawbacks of the known processes, the present invention proposes a method of manufacturing HMF from a sugary liquid medium containing any proportion of at least one aldohexose and, preferably, that is composed of a solution or an aldohexose syrup.

OBJECTS OF THE INVENTION In this way, the invention aims to propose a method of manufacturing HMF, from a sugar solution or a syrup containing a high proportion of aldohexoses, such as glucose, galactose, mannose and iodine, or of polysaccharides, such as cellulose or starch, and / or oligoholosides such as sucrose, lactose, maltose or cellobiose, with yields of transformation of sugars and production of HMF sufficiently high to be able to perform profitable industrial production . The essential objective of the invention is to propose a process for manufacturing HMF from a sugar solution or a syrup whose sugars are only composed of aldohexose (s) and / or polysaccharides and / or oligoholosides. The invention also aims to reduce the production cost of the HMF by decreasing the price of the raw material without increasing the price of the process. The main objective of the invention is to authorize the direct use of a greater variety of sugar solutions as raw material for the manufacture of HMF, including sugar solutions extracted from natural products, such as topinambo, betavel, sugar cane, corn, wheat, etc. , or sugary solutions obtained from the hydrolysis of sugars of natural origin containing as many aldohexoses as ketohexoses, as well as residual ósidos. The invention also aims to decrease the cost of the separation steps and increase the rate of sugar transformation in HMF. The essential aim of the invention is to propose a manufacturing process in a single step, which can be applied continuously and produce a HMF solution of high purity. The invention also aims to propose a process for the manufacture of HMF by heterogeneous acid catalysis and heating in a single stage, which is fast, low pollutant and cost effective regardless of the size and capacity of the installation, but in particular the small or medium installations. Thus, the present invention aims at a process for the manufacture of hydroxymethylfurfural (HMF) from a liquid medium containing at least one aldhexose and / or at least one oside capable of releasing an aldohexose, by heating the liquid medium to a temperature above 100 ° C, in the presence of an acid heterogeneous catalyst. This process is essentially characterized by simultaneously contacting the liquid medium with at least two different acid catalysts: the first, an aluminosilicate in protonic form with a Si / Al ratio of less than 4, preferably between 2 and 4 and, the second, an aluminosilicate in protonic form Si / Al ratio greater than 5.

SUMMARY OF THE INVENTION Indeed, it was found that the combination of two heterogeneous acid catalysts, the first of which has a lower acidity than the second according to the BRONSTED formula, allows a high conversion rate of aldohexoses to be obtained without any type of inconvenience. . Therefore, in this process two acid catalysts in protonic form are applied, which present different BRONSTED acidity indexes.

In this invention, the second catalyst is a zeolite selected to transform into HMF the ketohexoses, in particular the fructose, with a selectivity of transformation greater than 90% when used alone, under the operating conditions of the reaction (temperature, pressure, initial concentrations, expenses); while the first catalyst is a zeolite whose acidity (according to the BRONSTED formula) is less than that of the second. This second catalyst is preferably selected to transform the ketohexoses into HMF, in particular fructose, with an HMF yield greater than 50% when it is only used under the operating conditions of the reaction. According to the invention, the liquid medium is a concentrated aqueous solution, in particular a syrup containing more than 150 g / l of aldohexose (s) and / or ósido. The advantage of this first catalyst is that it is a zeolite, especially a faujasite Y in proton form. The Si / Al ratio of this first catalyst is of the order of 2.5 to 3. In this invention, this first catalyst has the advantage that it has a three-dimensional structure that has pores of about 7.5 A in diameter, connected to gaps of about 13 A of diameter arranged in cubic symmetry. The second catalyst is a zeolite, in particular a mordenite H. The Si / Al ratio of that second catalyst is between 5 and 20, in particular of the order of 10. According to the invention, the liquid is heated to a temperature higher than 150 ° C and below 200 ° C, specifically at 175 ° C. The process can be carried out more advantageously, by continuous circulation of the liquid at least in a multilayer reactor, in particular a pulsating column, in the presence of catalysts, in countercurrent suspension of the liquid medium, continuously extracting the HMF in a solvent not miscible with the liquid that circulates against the current. An organic solvent is preferred, in particular methyl isobutyl ketone (MIBC). Pulsating columns are vertical extraction or separation devices in which pulses can be generated (refer, for example, to the document "Pulsed Perforated-Plate Columns, DH Logsdail, MJ Slaten, Handboo of Solvent Extraction, Teh C. Lo Malcom HI-Baird , Cari Hanson, Krieger Publishing Co pany, Malabar Florida, 1991, 11-2, pp. 355-372, mentioned herein by reference.) It should be noted that in a method of the invention, the pulsating column functions only as a separator. Also, and above all, of multicontatic reactor of continuous type, in this way, the reaction and the continuous selective extraction of the reaction product are carried out simultaneously in the column, in a single step. , in a continuous and in a single stage, ketoses by isomerization of aldoses It should be noted that in this aspect that the combined characteristics of the invention allow obtaining these sultados since it is possible to work with concentrated syrups (with Brix degrees higher than 65) at high temperatures, with a short duration of the reaction, the reaction conditions strongly shift the balance. Another object of the present invention is the method that includes the combination of all of the features mentioned above or below, or part thereof.

BRIEF DESCRIPTION OF THE FIGURE Other characteristics and advantages of this invention appear in the reading of the following description, which refers to the single attached figure, where an outline of a segment of a pulsating column is represented that is part of a facility that works with the same procedure of this invention.

DESCRIPTION OF THE PREFERRED MODALITY This installation has a feeder (1) in sugar solution, and feeders (2 and 3) of acid catalysts. The feeder (2) supplies the first catalyst, for example, a faujasite? in powdered proton form, with a Si0 / Al2? 3 ratio of 6.5, that is, a Si / Al ratio of 3.25. This zeolite has pores of 0.75 nanometers in diameter attached to gaps 1.3 nanometers in diameter within a cubic symmetric structure. The feeder (3) supplies the second catalyst, for example, an order in protonic form, with a Si / Al ratio of 10. This catalyst is also present in a pulverulent form. The two catalysts are mixed and suspended in the sugar solution in a mixer (4). The mixture obtained is introduced into the upper part (5) of a booster column (6) controlling the temperature, which is maintained above 150 ° C, especially in the order of 175 ° C. Simultaneously in the lower part (7) of the pulsating column (6) an extraction solvent of the produced HMF is introduced. As the sugar solution is an aqueous solution, the extraction solvent used is the MIBC. In the upper part (5) of the pulsating column (6) the extraction solvent that circulated countercurrent and was loaded with HMF is recovered. This solvent loaded with HMF passed through an evaporator (8) that supplies the outlet (9) with a concentrated HMF solution free of sugars and by-products, especially free of aldohexoses. In the lower part (7) of the pulsating column (6) the rest of the sugar solution not transformed into HMF is recovered with the catalysts in suspension. This mixture is passed through a filter (10) that allows to separate the liquid and solid phases. The solid phase, constituted by catalysts, is recycled directly or by means of a regeneration furnace (11) or by another regularization procedure, in the mixer (4). The liquid phase is evacuated directly or carried to a scrubber. With such an installation a concentrated solution of pure HMF can be continuously produced from a sugar solution, which is continuously introduced into the feeder (1) and which can have any proportion, important or not, of aldohexoses or of ósidos able to liberate aldohexosas. For example, this solution may be composed of sucrose or a solution of inverted sugars (50% glucose and 50% fructose) or a solution of fructose and glucose with a higher proportion of glucose, even a glucose solution pure It should be noted that when the initial solution has ósidos, the hydrolysis of these in simple sugars (aldohexosas or ketohexosas) and the transformation of these simple sugars in HMF, is performed in a single stage in the pulsating column (1), keep going. It is also noteworthy that in this invention, which allows aldohexosas to be transformed into HMF, the operating conditions of the reaction are chosen to minimize the production of degradation products or by-products of the reaction other than sugars and HMF. Therefore, the selectivity and the HMF yield of the overall reaction are not the only criteria that will be optimized.

COMPARATIVE EXAMPLE 1 In a 4-liter autoclave, 2.5 liters of MIBC with a ratio of 6.5 organic phase to aqueous phase, and 350 ml of concentrated aqueous glucose solution at 200 g / 1, as well as proton-shaped mordenite are introduced. at a rate of 10 9 by 65 9 of glucose, that is, 10.8 g. The temperature of the autoclave is increased to 165 ° C, at a pressure of 10 bars. After 30 minutes of stirring, the contents of HMF, fructose, glucose and sugar in solution are determined by high pressure liquid chromatography (HPLC). Thus, the molar ratios of transformation of the initial glucose into soluble products are obtained, that is, the products adsorbed by the solids are not included. A molar conversion coefficient of glucose in HMF (number of moles of soluble HMF obtained / number of moles of initial glucose) of 8% is obtained. The molar ratio of transformation of glucose in HMF and fructose is 15%. The molar ratio of total transformation in HMF, fructose and mannose is 17%.

EXAMPLE 2 In the same operating conditions as Example 1, faujasite is added simultaneously in proton form in the ratio Si / Al equal to 3.25. In this example, the amount of faujasite that was used was half the amount of mordenite, that is, 5.4 g. A molar conversion coefficient of glucose in HMF of 10% is obtained. The molar ratio of transformation of glucose in HMF and fructose is 28% and the molar ratio of total transformation in HMF, fructose and mannose is 33%.

EXAMPLE 3 This example is identical to Example 2, but the same amount of faujasite is used as mordenite, ie 10.8 g. The transformation molar ratio in HMF is 13%. The molar ratio of transformation in HMF and fructose is 34% and the molar ratio of total transformation in HMF, fructose and mannose is 41%.

EXAMPLE 4 This example is identical to Example 2, but double the amount of faujasite is used that of mordenite, that is, 21.6 g. The transformation molar coefficient in HMF and fructose is 35.5% and the total transformation molar coefficient in HMF, fructose and mannose is 43.5%. When comparing the results of comparative example 1 and those of example 2, we verified that the total transformation of glucose in HMF and in direct precursors of HMF (fructose and mannose) is doubled when a small amount of faujasite is added to it. The transformation is further improved in Examples 3 and 4. However, between Examples 3 and 4, the transformation is not significantly improved. On the contrary, in example 4 there is a noticeable increase in the production of undesirable by-products. The extraction of the HMF continuously in the countercurrent solvent in a facility such as the one presented, allows the equilibrium of the transformation of fructose and even of the mannose in HMF to be displaced and obtain a good conversion and a good selectivity. Thus, the HMF can be prepared directly from glucose or a mixture with bears consisting of aldohexoses such as glucose or from a precursor of aldohexose (s), optimizing the relative proportions of the two catalysts.

Claims (11)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property; Method of manufacturing hydroxymethylfurfural (HMF) from a liquid medium containing at least one aldohexose and / or an oside capable of releasing at least one aldohexose, in which the liquid is heated to a temperature above 100 °. C, in the presence of an acid heterogeneous catalyst, characterized in that the liquid is contacted simultaneously with at least two different acid catalysts, the former being an aluminosilicate in protonic form and with a Si / Al ratio of less than 4 and the second is an aluminosilicate in protonic form and with a Si / Al ratio greater than 5. Process according to claim 1, characterized in that the second catalyst is a zeolite chosen to guarantee a selectivity of transformation of ketohexoses in HMF. more than 90%, under the operating conditions of the reaction, and is also characterized in that the first catalyst is a zeolite whose acidity is less than of the second catalyst. Method according to one of claims 1 or 2, characterized in that the second catalyst is chosen to convert the ketohexose into HMF, with an HMF yield greater than 50% when it is only used under the operating conditions of the reaction . Method according to one of the preceding claims, characterized in that the first catalyst is a faujasite Y in proton form. Method according to one of claims 1 to 4, characterized in that the first catalyst has a Si / Al ratio of the order of 2.5 to 3. The method according to one of claims 1 to 5, characterized in that the second Catalyst is a proton-shaped mordenite. Method according to one of claims 1 to 6, characterized in that the second catalyst has a Si / Al ratio of between 5 and 20. The method according to one of claims 1 to 7, characterized in that the liquid medium It is a concentrated aqueous solution. 9. Process according to one of claims 1 to 8, characterized in that the aqueous solution is a syrup containing more than 150 g / l of aldohexose or of oside. 10. Process according to one of claims 1 to 9, characterized in that the liquid medium is heated to a temperature above 150 ° C and below 200 ° C, in particular of the order of 175 ° C. Method according to one of Claims 1 to 10, characterized in that the liquid medium is circulated continuously in at least one multistage reactor, in particular a pulsating column with catalytic converters against the liquid and the HMF is withdrawn from the liquid. continuous form in a solvent not immiscible with the liquid that circulated countercurrently.