CN102675045B - Method for preparing ethylene glycol and 1,2-propylene glycol by using saccharide solution - Google Patents

Abstract

The invention provides a method for preparing ethylene glycol and 1,2-propanediol from a high-concentration sugar solution. The reaction raw materials include sucrose, glucose, fructose, fructan, xylose, soluble xylooligosaccharides and soluble starch. In the method, high-concentration sugar is used as a reaction raw material, and a high-pressure pump feeding mode is adopted in the reaction process, and the reaction is carried out in a high-pressure reactor. Use 8, 9, 10 group transition metals iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum as hydrogenation active components, and metal tungsten, tungsten carbide, nitride, phosphide, tungsten oxide , Tungsten sulfide, tungsten chloride, tungsten hydroxide, tungsten bronze, tungstic acid, containing tungstate, metatungstate, metatungstate, paratungstic acid, paratungstate, peroxytungstic acid , peroxytungstate, and tungsten-containing heteropolyacids are catalytically active components to form a composite catalyst. Under the hydrothermal conditions of 120-300 ^o C and hydrogen pressure of 1-13 MPa, a high-concentration sugar solution can be realized through a one-step catalytic conversion process. Preparation of ethylene glycol and propylene glycol with high efficiency, high selectivity and high yield. The method provided by the invention can effectively solve the coking problem of high-concentration sugar in the catalytic conversion process, and realize the preparation of high-concentration ethylene glycol and propylene glycol from high-concentration sugar.

Description

A method for preparing ethylene glycol and 1,2-propanediol from sugar solution

technical field

The invention relates to a method for preparing ethylene glycol and 1,2-propanediol from a sugar solution, specifically a reaction process for preparing ethylene glycol and 1,2-propanediol from a high-concentration sugar solution through one-step catalytic hydrogenation degradation.

Background technique

Ethylene glycol and propylene glycol are important energy liquid fuels, and are also very important raw materials for polyester synthesis, for example, for polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and It can be used as antifreeze, lubricant, plasticizer, surfactant, etc. It is a widely used petrochemical basic raw material.

At present, the industrial production of ethylene glycol mainly adopts the route of petroleum raw materials, that is, ethylene oxide is obtained after epoxidation of ethylene, and then ethylene glycol is obtained by hydration [Document 1: Cui Xiaoming, Overview of Ethylene Glycol Production and Development at Home and Abroad, Chemistry Industry, 2007, 25, (4), 15-21. Literature 2: Process for preparing ethanediol by catalyzing epoxyethane hydration, Patent No.CN1463960-A; CN1204103-C]. The synthesis method relies on non-renewable petroleum resources, and the production process includes selective oxidation or epoxidation steps, which are technically difficult, low in efficiency, with many by-products, high material consumption and serious pollution.

The use of renewable biomass to prepare ethylene glycol and 1,2-propanediol can reduce the dependence of human beings on fossil energy materials, and is conducive to the realization of environmental friendliness and sustainable economic development. Glucose, sucrose, fructose, fructan, xylose, and soluble xylooligosaccharides are widely found in nature. With the development of agricultural technology, its output is increasing day by day. The development of sugar compounds to prepare ethylene glycol and propylene glycol can not only reduce the dependence on petroleum resources to a certain extent, but also help realize the deep processing of agricultural products to produce high value-added chemicals. At present, the technology of making polyhydric alcohols from sugar-based compounds [Document 3: Process for the preparation of lower polyhydric alcohols, patent, No. US5107018. Document 4: Preparation of flower polyhydric alcohols, patent, No. US5210335 Document 5: A method for the production of A new process for alcohol, CN200610068869.5 Document 6: A method for producing diols and polyols by cleavage of sorbitol, CN200510008652.0] generally includes three steps: (1) Starch undergoes gelatinization, enzymatic liquefaction, and enzymatic saccharification Obtaining glucose (2) Glucose is hydrogenated by precious metal ruthenium or nickel catalyst to obtain sorbitol (3) Sorbitol is hydrogenated under high temperature and pressure to produce polyols, mainly propylene glycol, glycerol, and ethylene glycol. Wherein, the yield of ethylene glycol is in the range of 10-30%. The reaction process is cumbersome. Another preparation route is to prepare ethylene glycol by catalytic hydrogenation conversion of cellulose under hydrothermal conditions [Document 4: Direct catalytic conversion of cellulose into ethylene glycol using nickel-promoted tungsten carbohydrate catalysts, Angew.Chem.Int.Ed.2008, 47 , 8510-8513. Document 5: transition metal-tungsten bimetallic catalysts for the conversion of cellulose into ethylene glycol, ChemSusChem 2010, 3, 63-66]. The method uses a tungsten carbide catalyst or a metal tungsten catalyst promoted by a transition metal to catalyze the conversion of cellulose to obtain ethylene glycol. Ethylene glycol yield can reach 60-75%. Under this catalyst system, it can also catalyze the conversion of sugar compounds such as glucose and fructose, and obtain ethylene glycol and propylene glycol with high selectivity [Document 6: A method for producing ethylene glycol from polyols, CN200810229065.8]. However, in the reaction process reported in Documents 5 and 6, the reaction concentration of the sugar raw material is 1wt%, the concentration of the product ethylene glycol is lower, and the solvent water accounts for 99wt% of the solution after the reaction. Since the products of ethylene glycol and propylene glycol in the industrial production process are separated by distillation. The boiling point of ethylene glycol is 197.5°C, and the boiling point of 1,2-propanediol is 188.2°C. Thus, a low product concentration will consume a large amount of energy for the distillation process. In order to improve the economy of the reaction process, it is very important to reduce the distillation energy consumption and increase the concentration of the product in the reaction process.

Contents of the invention

The object of the present invention is to provide a kind of method that sugar solution prepares ethylene glycol, propylene glycol. The sugar solution is a solution of sucrose, glucose, fructose, fructan, xylose, soluble xylooligosaccharides, and soluble starch. Through a one-step catalytic hydrogenation degradation process, ethylene glycol is prepared with high yield and high selectivity.

In order to achieve the above object, the technical scheme that the present invention takes is: with sugar solution (concentration is greater than 5wt%), comprise sucrose, glucose, fructose, fructan, xylose, soluble xylooligosaccharide, soluble starch as reaction raw material, solvent It is water, or C1-C6 alcohols, or a mixed solution thereof. During the reaction process, a liquid high-pressure pump feeding method is adopted. Before feeding, a certain amount of catalyst and solvent is pre-added at the bottom of the kettle. The amount of solvent is subject to the smooth stirring of the solid active component of the catalyst. Immerse the solid catalyst and be less than 1/3 of the volume of the reactor. In the reaction process, the amount of catalyst used in the reaction system is the amount of catalyst used to achieve the smooth progress of the reaction.

The catalyst includes a catalytically active component A and a catalytically active component B. The active component A and the active component B can be loaded on a common carrier, or a mixed catalyst can be formed in the form of mechanical mixing; the catalytically active component A includes One or more of the transition metals iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, and platinum of Groups 8, 9, and 10. The catalytically active component B includes inorganic compounds, organic compounds, and complexes of tungsten. tungsten, tungsten carbide, nitride, phosphide, tungsten oxide, tungsten sulfide, tungsten chloride, tungsten hydroxide, tungsten One or more of bronze, tungstic acid, tungstate, metatungstate, metatungstate, paratungstic acid, paratungstate, peroxytungstic acid, peroxytungstate, tungstic heteropolyacid ; Before feeding, add catalyzer in reactor, the catalyzer that adds in advance comprises catalytically active component A; If catalytically active component B is solid, it also adds in reactor in advance equally with catalytically active component A; If catalytic The active component B is a liquid, which can be added in whole or in part to the reactor before feeding, or can be added in whole or in part by a pump along with the sugar solution of the raw material; stir the reaction in the reactor; fill the reactor with hydrogen before the reaction , the reaction temperature is higher than 120°C, and the upper limit of the temperature is subject to the fact that the raw materials and products do not undergo thermal decomposition. The reaction time is not less than 5 minutes. The more preferred initial pressure of hydrogen in the reaction kettle at room temperature is 1-12MPa, the more preferred reaction temperature is 120-300°C, and the reaction time is not less than 5 minutes; the more preferred reaction temperature is 180-250°C, and the reaction kettle at room temperature The initial pressure of hydrogen is more preferably 3-7MPa.

The metal active component of the active component A in the catalyst is in the range of 0.02-3000 times by weight to the catalytically active component B (calculated by the weight of metal tungsten). Preferably the weight ratio is in the range of 0.1-100 times.

During the reaction process of producing ethylene glycol from glycosyl compounds, the intermediate species formed are unsaturated aldols, so catalytic hydrogenation is required to obtain the final polyols. Therefore, active component A having catalytic hydrogenation ability is required in the catalyst. The catalytically active component can be carried on a carrier, including activated carbon, aluminum oxide, silicon oxide, silicon carbide, zirconium oxide, zinc oxide, titanium dioxide, or one or more complexes. The loading amount of metal is 0.05-50wt%, preferably 0.5-30wt%. Or the catalytically active component A is a skeleton metal catalyst with the active component as the catalyst skeleton, such as Raney nickel and the like.

The active component B in the catalyst is one or more of tungsten-containing inorganic compounds, organic compounds, complexes, and metal elements, including metal tungsten, tungsten carbide, nitride, phosphide, and tungsten oxide , tungsten sulfide, tungsten chloride, tungsten hydroxide, tungsten bronze, tungstic acid, tungstate, metatungstate, metatungstate, paratungstic acid, paratungstate, peroxytungstic acid, One or more of peroxytungstate and tungsten heteropolyacid. During the reaction, the tungsten species in the catalyst played an important catalytic role in the catalytic degradation of polyols.

The active component A and the active component B can be supported on a common carrier, or can be mechanically mixed to form a mixed catalyst.

When high-concentration sugar solution is used as the reaction raw material, because the high-concentration sugar reaction raw material is prone to side reactions such as polymerization under high temperature reaction conditions, thereby inhibiting the activity of the catalyst, and eventually leading to the termination of the reaction of preparing ethylene glycol and propylene glycol, so it must be targeted Properly adopt a special process to suppress the occurrence of side reactions and improve the selectivity of the target reaction. In the method of the present invention, the high-concentration sugar solution reaction raw material is fed by a liquid high-pressure pump, and is continuously added to the reaction kettle during the reaction process. Before feeding, a certain amount of catalyst and solvent is pre-added at the bottom of the kettle. The amount of solvent depends on the smooth stirring of the solid active components of the catalyst. If it is too high, it will cause polymerization and coking. The solvent should have thermal stability at the reaction temperature and can be water or alcohols. The reaction is carried out under stirring conditions. In the process of feeding high-concentration sugar raw materials, the sugar raw materials are firstly diluted by the solvent left at the bottom of the reaction kettle, and the diluted sugar is continuously catalytically converted and consumed, so that the sugar concentration in the reaction kettle is always maintained at At lower concentration levels, the concentration of the reaction material is differentiated in the reaction while the concentration of the product is integrated. Through the technical means adopted in the present invention, not only can the polymerization coking problem of high-concentration sugar be successfully solved, but at the same time, compared with the way of loading sugar raw materials at one time, since the molar ratio of catalyst and reactant in the reaction process is improved, thereby suppressing The side reaction occurs, and the selectivity of the target product is improved, which has a remarkable effect.

The concentration of the reaction raw material sugar solution is 5wt%-90wt%.

The embodiment listed below is carried out in the autoclave, but does not rule out can be optimized by reactor design, for example, adopts the form of multi-stage reactor series connection, or slurry bed reactor, realizes the sufficient reaction of sugar reaction raw material, obtains Better response results.

Advantages of the present invention: use high-concentration sugar solution as reaction raw material, including glucose, sucrose, fructose, fructan, xylose, soluble xylooligosaccharide, and soluble starch as raw materials to prepare ethylene glycol and propylene glycol. Biomass-based polyol technology has the advantages of high concentration of reactants, easy control of the reaction process, high concentration of ethylene glycol and propylene glycol products, and high yield. It can greatly reduce the distillation energy consumption of reaction products and improve the economy of the reaction process. sex.

The invention provides a method for preparing ethylene glycol and propylene glycol by catalytic conversion of a high-concentration sugar solution. The concentration of the sugar solution as a reaction raw material is 5wt%-90wt%. The reaction process is easy to control, and the yield and concentration of ethylene glycol and propylene glycol in the product are high, which can greatly reduce the cost of product distillation.

The present invention will be described in detail through specific examples below, but these examples do not limit the content of the present invention.

Detailed ways

Example 1

Preparation of the metal catalyst Ru/AC: impregnate the activated carbon support with ruthenium trichloride aqueous solution, dry at 120°C for 12h, and then reduce it in a hydrogen atmosphere at 500°C for 1h to obtain the catalyst Ru/AC (2wt%Ru).

Example 2

Preparation of metal catalyst W/AC: impregnate activated carbon support with ammonium metatungstate aqueous solution, dry at 120°C for 12h, and then reduce in hydrogen atmosphere at 700°C for 1h to obtain catalyst W/AC (30wt%W).

Example 3

Preparation of Ni-W ₂ C/AC catalyst: Reference Angew.Chem.Int.Ed.2008, 47, 8510-8513, the ammonium metatungstate and nickel nitrate are made according to the ratio of tungsten/nickel weight ratio of 15:1 The mixed solution, wherein the mass volume concentration of ammonium metatungstate is 0.4 g/ml. Then, the mixed solution was impregnated with activated carbon support (AC). After being dried in an oven at 120°C for 12 hours, the catalyst precursor was placed in an _H2 atmosphere for a temperature-programmed carbothermal reaction. The specific reaction process was as follows: 2.0 g of the precursor was heated from room temperature to 400°C in a quartz reaction tube for 1 hour, and then heated with 1 °C/min, the temperature was raised to 700 °C and kept for 1 hour for carbonization, and the hydrogen flow rate was 100ml/min. A Ni-W ₂ C/AC catalyst with a tungsten loading of 30 wt % and a nickel loading of 2 wt % was obtained, expressed as Ni-W ₂ C/AC (2 wt % Ni-30 wt % W ₂ C).

Example 4

Preparation of Pd-W ₂ C/AC catalyst: The method is the same as in Example 3, except that the nickel nitrate solution is replaced by palladium chloride solution to obtain Pd-W with 30wt% tungsten loading and 5wt% palladium loading. ₂ C/AC catalyst, expressed as Pd-W ₂ C/AC (5 wt% Pd-30 wt% W ₂ C).

Example 5

High-pressure pump feed method catalytic conversion experiment: 0.33g catalyst (0.15g Ru/AC 5wt%, 0.18gW/AC 30wt%) and 30ml water were added to a 300ml reactor, and hydrogen gas was introduced to replace the gas three times. 5MPa, the temperature was raised to 240°C with stirring. After the temperature of the reactor is raised to 240° C., a high-pressure liquid phase pump is used to feed a 50 wt % sugar solution into the reactor at a certain rate to start the reaction. After the feed of the reaction raw materials is finished, the reaction is extended for 60 min. After the reaction, cool down to room temperature, take the centrifuged supernatant, separate it on a high-performance liquid chromatography calcium-type ion-exchange column and detect it with a differential refraction detector. In the product yield, only the target products ethylene glycol, 1,2-propanediol and hexahydric alcohols (including sorbitol and mannitol) are calculated, and other liquid products include butylene glycol, ethanol, unknown components, and gas products (CO ₂ , CH ₄ , C ₂ H ₆ etc.) the yield was not calculated.

Comparative Example 1

Catalytic conversion experiment with one feeding method: 5.0g sugar, 0.33g catalyst and 100ml water were added to a 300ml reactor, and hydrogen gas was introduced to replace the gas three times, then filled with hydrogen to 5Mpa, heated to 240°C under stirring, and reacted for 2h. Cool down to room temperature and take the liquid product for analysis. The analysis method is the same as in Example 5.

Example 6

The results of the catalytic conversion experiment of the high-pressure pump feeding method involved in the present invention are compared with the results of the catalytic conversion experiment of the one-time charging method in the open literature.

Table 1 Comparison of catalytic conversion results between the invention and published patents and literature methods

Note: ^a . The average concentration of the reaction raw materials is the total average concentration of the sugar raw materials added from the sugar solution to the reaction kettle with a certain amount of solvent reserved in advance after the liquid pump feeding is completed.

The amount of ^b tungstic acid is 0.05g, and the amount of Ru/AC is 0.15g.

^c catalyst dosage 0.15g Ru/AC 5wt%, 0.18g W/AC 30wt%.

As can be seen from the above results, when the pump feeding method is adopted, when glucose is used as raw material, ethylene glycol is mainly produced with high selectivity, and the yield ratio of ethylene glycol and propylene glycol is 10:1; while sucrose or fructose is used as raw material , the yield of 1,2-propanediol is greatly improved, and the yield ratio of ethylene glycol and propylene glycol is 1:1 or 1:6, respectively.

The yield of ethylene glycol and propylene glycol obtained by the pump feeding method is significantly higher than that of the direct charging reaction, and the total yield of ethylene glycol and propylene glycol can be increased by more than 1 times, and the effect is remarkable.

Obviously, the method provided by the present invention can be used for the catalytic conversion of high-concentration sugar raw materials to produce ethylene glycol and propylene glycol, and the yield and selectivity of the product are high, which is a significant technical improvement compared with the existing methods.

Example 7

The conversion results of different concentrations of glucose under the feeding mode of liquid pump

Except that the concentration of the glucose solution is different, the reaction conditions are the same as in Example 4. When the concentration of the sugar solution is higher than 50wt%, a hot water solvent is used to increase the solubility of the sugar.

Table 2 The conversion results of different concentrations of glucose under the feeding mode of liquid pump

Note: ^a . The average concentration of the reaction raw materials is the total average concentration of the sugar raw materials added from the sugar solution to the reaction kettle with a certain amount of solvent reserved in advance after the liquid pump feeding is completed.

Claims (9)

1. A sugar solution prepares the method for ethylene glycol, 1,2-propanediol, it is characterized in that: be reaction raw material with concentration greater than 5wt% sugar solution, carry out catalytic hydrogenation reaction in airtight reactor, in reaction process High-pressure liquid pump feeding method is adopted; before feeding, catalyst and solvent are added to the reactor, and the amount of solvent is subject to the smooth stirring of the catalyst; the reaction is carried out under stirring conditions; The catalyst used includes catalytically active component A and catalytically active component B. Active component A and active component B can be loaded on a common carrier, or can be mechanically mixed during the reaction to form a mixed catalyst. The catalytically active component A includes one or more of the transition metals iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, and platinum of the 8th, 9th, and 10th groups with catalytic hydrogenation properties, Before feeding, add catalyzer in reactor, the catalyst that adds in advance comprises catalytically active component A; Simultaneously, if catalytically active component B is solid, it also adds in the reactor in advance equally with catalytically active component A; If Catalytically active component B is a liquid, which can be added in whole or in part to the reactor before feeding, or can be added in whole or in part by a pump along with the raw material sugar solution; Stir the reaction in the reaction kettle; fill the reaction kettle with hydrogen before the reaction, the reaction temperature is ≥120°C, and the reaction time is not less than 5 minutes; During use, based on the weight of metal tungsten, the weight ratio of the metal active component of active component A of the catalyst to the active component of catalytic active component B is 0.02-3000:1; Catalytically active component B is metal tungsten, tungsten carbide, nitride, phosphide, tungsten oxide, tungsten sulfide, tungsten chloride, tungsten hydroxide, tungsten bronze, tungstic acid, tungstate , Metatungstic acid, metatungstate, paratungstic acid, paratungstate, peroxytungstic acid, peroxytungstate, tungstic heteropoly acid, or one or more of them; The catalytically active component A may also exist in the form of a skeleton metal; Or the catalytically active component A is loaded on a carrier, and the carrier is a composite carrier of one or more of activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, and titanium dioxide; the active component gold The content on the catalyst is 0.05-50wt%. 2. according to the described method of claim 1, it is characterized in that: the solvent that adds in advance at the bottom of reaction still is water or C1-C6 alcohols or the mixed solution of two or more in them, and its add-on can immerse solid catalyst and Less than 1/3 of the volume of the reactor; In the reaction process, the amount of catalyst used in the reaction system is the amount of catalyst used to achieve the smooth progress of the reaction. 3. The method according to claim 1, characterized in that: before the reaction, the reaction kettle is filled with hydrogen, and the initial pressure of hydrogen at room temperature is 1-12MPa; the reaction temperature is ≥120°C, and the upper limit of the temperature is subject to the fact that the product does not undergo thermal decomposition . 4. The method according to claim 1 or 3, characterized in that: the reaction temperature is 120-300° C., and the initial pressure of hydrogen in the reactor at room temperature is 3-7 MPa. 5. according to the described method of claim 4, it is characterized in that: reaction temperature is 180-250 ℃. 6. The method according to claim 1, characterized in that: the loading amount of the active component A of the catalyst is 0.5-30wt%. 7. The method according to claim 1, characterized in that: the concentration of the reaction raw material sugar solution is 10wt%-90wt%; the amount of the catalyst is the catalyst amount. 8. The method according to claim 1, characterized in that: the metal active component of the catalytic active component A and the catalytic active component B are calculated by the weight of metal tungsten, and the weight ratio during use is 0.1-100: 1. 9. according to the described method of claim 1, it is characterized in that: described sugar solution is sucrose, glucose, fructose, fructo A solution of one or more of sugar, xylose, soluble xylooligosaccharides, and soluble starch; the solvent is water or C1-C6 alcohols, or a mixed solution of two or more of them.