CN102731253A - Method capable of inhibiting generation of cyclic ether alcohol and used for preparing glycol by catalytic conversion of cellulose - Google Patents

Abstract

The invention provides a method for preparing ethylene glycol by catalytic conversion of cellulose that inhibits the formation of cyclic ether alcohols. The catalytic hydrogenation reaction process is carried out under stirring conditions in a closed high-pressure vessel, the reaction temperature is ≥ 150 ° C, and the hydrogen pressure is 0.1 during the reaction process. -15MPa, the mass content of the reactant in the aqueous solution is 1-30wt%, and the reaction time is not less than 5min. The catalyst contains an active component A with catalytic hydrogenation function, a tungsten-containing active component B with a catalytic cellulose degradation function, and a rhenium-containing catalytic active component C. In the reaction product, the cyclic ether alcohol by-product close to the boiling point of ethylene glycol is significantly reduced, thereby reducing the impurities in the subsequent rectification and separation product of the ethylene glycol product, and improving the product purity of the ethylene glycol.

Description

A method for producing ethylene glycol by catalytic conversion of cellulose inhibiting the generation of cyclic ether alcohols

technical field

The invention relates to a method for preparing ethylene glycol, in particular to a method for preparing ethylene glycol by catalytic conversion of cellulose that suppresses the formation of cyclic ether alcohols.

Background technique

CN1204103-C】。利用可再生的生物质资源合成乙二醇技术是实现化石能源资源替代的重要途径之一【文献3：Process forthe preparation of lower polyhydric alcohols，patent，No.US5107018.文献4：Preparation of lower polyhydrical cohols，patent，No.US5210335.文献3：一种生产乙二醇的新工艺，CN200610068869.5.文献5：一种由山梨醇裂解生产二元醇和多元醇的方法，CN200510008652.0】。Ethylene glycol is an important basic energy chemical. In 2010, the consumption of ethylene glycol in the world was close to 20 million tons. It is mainly used in the synthesis of chemical fiber polyester, unsaturated resin, automobile antifreeze and chemical intermediates. At present, the production of ethylene glycol mainly depends on petroleum ethylene resources [Document 1: Cui Xiaoming, Overview of the Development of Ethylene Glycol Production at Home and Abroad, Chemical Industry, 2007, 25, (4), 15-21. Document 2: Process for preparing Ethanediol by catalyzing epoxyethane hydration, Patent No.CN1463960-

CN1204103-C]. Using renewable biomass resources to synthesize ethylene glycol technology is one of the important ways to replace fossil energy resources [Document 3: Process for the preparation of lower polyhydric alcohols, patent, No. US5107018. Document 4: Preparation of lower polyhydric cohols, patent, No. US5210335. Document 3: A new process for producing ethylene glycol, CN200610068869.5. Document 5: A method for producing diols and polyols by cleavage of sorbitol, CN200510008652.0].

Cellulose is the most productive biomass resource ubiquitous in nature. Moreover, there are abundant carbon, hydrogen, and oxygen atoms in the molecular structure of cellulose, which is very similar to the elemental composition in ethylene glycol molecules. Therefore, the reaction of using cellulose as the raw material to prepare ethylene glycol has high atom economy and is an extremely ideal route for the utilization of cellulose resources.

In 2008, researchers from Dalian Institute of Chemical Physics discovered for the first time that cellulose can be directly catalytically converted on tungsten-based catalysts to obtain ethylene glycol with high selectivity [Document 6: Direct catalytic conversion of cellulose into ethylene glycol using nickel-promotedtungsten carbide catalysts , Angew. Chem. Int. Ed. 2008, 47, 8510-8513. Document 7: transition meta -tungsten bimetallic catalysts for the conversion of cellulose into ethylene glycol, ChemSusChem 2010, 3, 63-66. Document 8: A new 3D me s oporous carbon replicated from commercial silica as a catalyst support for direct conversion of cellulose into ethylene glycol, Chem.Commun., 2010, 46, 862864.]. During the reaction, the cellulose is completely converted, and the yield of ethylene glycol is as high as 60-75%.

On the other hand, further research has found that in the process of producing ethylene glycol from cellulose, in addition to the products of ethylene glycol, propylene glycol, and butanediol, there are also some alcohols with cyclic ether structures, including tetrahydro Furfuryl alcohol (boiling point 178C), 3-hydroxytetrahydrofuran (boiling point 181C), and 2-hydroxymethyltetrahydropyran (boiling point 187C). The boiling point of these cyclic ether alcohols is relatively close to the boiling point of ethylene glycol at 197.8C, so it is difficult to effectively separate and remove them by rectification from ethylene glycol products. And these products produce unfavorable influence when ethylene glycol is used in polyester synthesis process.

Therefore, how to reduce or eliminate the generation of undesirable cyclic ether alcohol by-products while ensuring a high yield of ethylene glycol in the reaction is a problem to be solved.

Contents of the invention

The invention provides a method for preparing ethylene glycol by catalytic conversion of cellulose capable of suppressing the formation of cyclic ether alcohol.

The catalytic hydrogenation reaction process of cellulose is carried out under the condition of stirring in a closed high-pressure vessel, the reaction temperature is ≥150°C, the hydrogen pressure is 0.1-15MPa during the reaction process, the mass content of the reactant in the aqueous solution is 1-30wt%, and the reaction time is not Less than 5 minutes, the catalyst used contains active component A with catalytic hydrogenation function, tungsten-containing active component B with catalytic cellulose degradation function, and rhenium-containing catalytic active component C, and the amount is the catalyst amount; In the process, the weight ratio of the metal active component of catalyst A to the active component of catalyst B (in terms of metal tungsten weight) is between 0.02-3000 times, and the preferred range is between 0.05-100 times; the metal active component of catalyst A and The weight ratio of the active components of the catalyst C (based on the weight of rhenium metal) is in the range of 0.02-3000 times, preferably in the range of 0.1-100 times.

The catalyst used contains active component A with catalytic hydrogenation function, tungsten-containing active component B with catalytic cellulose degradation function, and rhenium-containing catalytic active component C; active component A includes cobalt, nickel, ruthenium, One or more metals or metal oxides of rhodium, palladium, iridium, platinum; the active component B containing tungsten includes tungsten elemental substance and various compounds of tungsten, specifically including metal tungsten, tungsten carbide, nitrogen Tungsten oxide, tungsten phosphide, tungsten oxide, tungsten sulfide, tungsten chloride, tungsten hydroxide, tungsten bronze, tungstic acid, tungstate, metatungstic acid, metatungstate, paratungstic acid , paratungstate, peroxytungstic acid, peroxytungstate, tungsten heteropolyacid or one or more of them; rhenium-containing catalytic active component C includes metal rhenium, rhenium +1, +2, + 3, +4, +5, +6, +7 valence oxides (such as: rhenium heptoxide Re ₂ O ₇ , rhenium dioxide ReO ₂ , rhenium trioxide ReO ₃ , rhenium trioxide Re ₂ O ₃ and One or two of rhenium oxide (Re ₂ O, etc.).

The reaction temperature is ≥150°C, and the temperature range is 150-350°C; the preferred reaction temperature is 220-280°C, the preferred hydrogen pressure is 3-10MPa during the reaction, and the preferred reaction time is 30min 3h.

The catalyst active component A, active component B, and active component C can be loaded on the porous carrier by three kinds, or can be loaded on the porous carrier by any two kinds of free combinations, or can be loaded separately A composite catalyst is formed on a porous carrier, the carrier is activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, titanium dioxide or more than two kinds of composite carriers; the content of the active component metal on the catalyst is 0.05-50wt%;

The catalyst active components A, B, and C can also exist independently in a non-supported form;

The mass ratio of the reaction raw material to the catalyst (based on the mass of the active metal) is 1:1-30000:1, preferably 3:1-3000:1, and more preferably 4:1-1000:1.

The cellulose reaction raw materials are derived from plants, including corn cobs, or straws, and the straws are derived from corn, wheat, cotton, sorghum, soybeans, rice, sugarcane, or urban domestic wastewater, wood, forestry waste, recycled paper products.

The catalytic hydrogenation reactor adopts a closed high-pressure vessel, including batch reactors, semi-batch reactors, slurry bed reactors, and circulating fluidized bed reactors.

Beneficial effect of the present invention:

The method provided by the invention can not only maintain the high yield of ethylene glycol by catalytic conversion of cellulose, but also reduce and eliminate the generation of cyclic ether alcohol by-products, reduce the difficulty of rectification and separation of ethylene glycol products, and improve the efficiency of rectification. Purity of distilled glycol products.

Detailed ways

Example 1

Take 10kg of corn stalk powder (20-40 mesh), add water to make the water content 30wt%, put it in a steam explosion reactor at 160°C, (pressure 1.0MPa) constant pressure for 60 seconds, and then perform steam explosion operation. To the obtained 8kg solid residue (dry weight), add 50kg concentration of 1wt% NaOH aqueous solution to it, soak 12h under room temperature 25 ℃, add 50kg concentration wherein to it after filtering out and be 1wt% hydrogen peroxide, soak 12h at room temperature, then Rinse with clear water until neutral to obtain 5 kg (dry weight) of corn stalk cellulose raw material.

The corn stalk powder is replaced by sorghum stalk, and the corresponding cellulose raw material can be obtained according to the same method as above.

Example 2

Get 10.0g corn stalk cellulose (gained in embodiment 1) and add 100ml water, 0.1g tungstic acid, 0.1g 5%Ru/AC catalyst, 0.05g 0.5%Ir-1%ReOx/AC (0＜x≤3.5) The reaction was carried out in a high-pressure reactor at 250° C. for 2 hours, the stirring speed was 500 rpm, and the hydrogen pressure was 7 MPa during the reaction. After the reaction is finished, cool down to room temperature, release the pressure, open the kettle and centrifuge to obtain a liquid product, and analyze the yield of polyol product and cyclic alcohol by-product by gas chromatography.

Comparative Example 1

Get 10.0g corn stalk cellulose (obtained in embodiment 1), add 100ml water, 0.1g tungstic acid, 0.1g 5%Ru/AC catalyst, 0.05g 0.5%Ir/AC in autoclave 250 ℃ carry out reaction 2h , a stirring speed of 500 rpm, and a hydrogen pressure of 7 MPa during the reaction. After the reaction was finished, it was lowered to room temperature, the pressure was released and the kettle was opened and centrifuged to obtain a liquid product, and the yield of the polyol product was analyzed by liquid chromatography.

Example 3

Get 10.0g sorghum stalk cellulose (gained in embodiment 1) and add 100ml water, 0.1g ammonium metatungstate, 0.1g Raney nickel catalyst, 0.05g 2%Ru-0.2%Re/SiO ₂₄₀ in autoclave The reaction was carried out at ℃ for 2 hours, the stirring speed was 500 rpm, and the hydrogen pressure was 7 MPa during the reaction. After the reaction is finished, cool down to room temperature, release the pressure, open the kettle and centrifuge to obtain a liquid product, and analyze the yield of polyol product and cyclic alcohol by-product by gas chromatography.

Comparative Example 2

Get 10.0g sorghum stalk cellulose (obtained in embodiment 1) and add 100ml water, 0.1g ammonium metatungstate, 0.1g Raney nickel catalyst, 0.05g ₂ %Ru/SiO 250 ℃ carry out reaction in autoclave 2h , a stirring speed of 500 rpm, and a hydrogen pressure of 7 MPa during the reaction. After the reaction is finished, cool down to room temperature, release the pressure, open the kettle and centrifuge to obtain a liquid product, and analyze the yield of polyol product and cyclic alcohol by-product by gas chromatography.

Example 4

Take 10.0g of microcrystalline cellulose and add 100ml of water, 0.5g of 30% W ₂ C/AC, 0.1g of 1% Rh/AC, 0.05g of ReO ₂ in an autoclave at 240°C for 2 hours, with a stirring speed of 500 rpm , The hydrogen pressure was 7MPa during the reaction. After the reaction is finished, cool down to room temperature, release the pressure, open the kettle and centrifuge to obtain a liquid product, and analyze the yield of polyol product and cyclic alcohol by-product by gas chromatography.

Comparative Example 3

Take 10.0g of microcrystalline cellulose and add 100ml of water, 0.5g of 30% W ₂ C/AC, 0.05g of MoO ₃ in an autoclave at 240°C for 2 hours, stirring at 500 rpm, and hydrogen pressure of 7MPa during the reaction. After the reaction is finished, cool down to room temperature, release the pressure, open the kettle and centrifuge to obtain a liquid product, and analyze the yield of polyol product and cyclic alcohol by-product by gas chromatography.

Example 5

Comparison of product composition and yield of cellulose conversion to ethylene glycol under different reaction conditions. As shown in Table 1.

Table 1. Comparison of reaction results of cellulose conversion to ethylene glycol under different catalyst conditions

From the results listed in the table above, it can be seen that when the catalyst used for the cellulose conversion reaction contains tungsten active components, rhenium active components and hydrogenation active components, the by-products of cyclic ether alcohol produced in the reaction process are significantly less Compared with the reaction products obtained by catalysts containing three active components at the same time, it reflects significant technological progress.

Example 6

Rectification of ethylene glycol products. Take 1L of the liquid product obtained from the production of ethylene glycol from cellulose, and carry out rectification under reduced pressure in a rectification device with a vacuum degree of 0.1 bar. The theoretical plate number of the rectification column is 10, and the reflux ratio is 5. Collect the product in the temperature range of 120-125C, and analyze the purity of the product by gas chromatography. The resulting product purity is shown in Table 2.

Table 2. Purity comparison of rectification fractions of cellulose conversion to ethylene glycol products under different catalyst conditions

As can be seen from Table 2, after the rectification of the ethylene glycol product obtained in the method of the present invention, the content of cyclic ether alcohol in the product is significantly lower than that of the results of the comparative example, reflecting a significant technical progress. In the method provided by the present invention, a three-component catalyst is used to catalyze the conversion of cellulose to ethylene glycol in a one-step method, while greatly reducing or eliminating the by-product of cyclic ether alcohol, so as to reduce the difficulty of ethylene glycol rectification and purification, Improve the quality of glycol products.

Claims (7)

1. A method for preparing ethylene glycol by catalytic conversion of cellulose that suppresses the generation of cyclic ether alcohols, characterized in that: the catalytic hydrogenation reaction process is carried out under stirring conditions in a closed high-pressure vessel, and the reaction temperature is ≥150 ° C. During the reaction, hydrogen gas The pressure is 0.1-15MPa, the mass content of reactants in the aqueous solution is 1-30wt%, and the reaction time is not less than 5min. The tungsten active component B and the rhenium-containing catalytic active component C are used in a catalyst amount; during use, the weight ratio of the metal active component of catalyst A to the active component of catalyst B (by weight of metal tungsten) is 0.02-3000 The weight ratio of the metal active component of catalyst A to the active component of catalyst C (based on the weight of rhenium metal) is in the range of 0.02-3000 times. 2. according to the described method of claim 1, it is characterized in that: in the catalyst used, contain active component A with catalytic hydrogenation function, tungsten-containing active component B with catalytic cellulose degradation function, and rhenium-containing catalytic activity Component C; active component A includes one or more metals or metal oxides of cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum; active component B containing tungsten includes tungsten elemental substance and tungsten Various compounds, specifically including metallic tungsten, tungsten carbide, tungsten nitride, tungsten phosphide, tungsten oxide, tungsten sulfide, tungsten chloride, tungsten hydroxide, tungsten bronze, tungstic acid, tungsten One or more of salt, metatungstate, metatungstate, paratungstic acid, paratungstate, peroxytungstic acid, peroxytungstate, tungstic heteropolyacid; rhenium-containing catalytic active group Part C includes one or two of metal rhenium, +1, +2, +3, +4, +5, +6, +7 valence state oxides of rhenium; The catalyst active component A, active component B, and active component C can be loaded on the porous carrier by three kinds, or can be loaded on the porous carrier by any two kinds of free combinations, or can be loaded separately A composite catalyst is formed on a porous carrier, the carrier is activated carbon, alumina, silicon oxide, silicon carbide, zirconia, zinc oxide, titanium dioxide or more than two kinds of composite carriers; the content of the active component metal on the catalyst is 0.05-60wt%; The catalyst active components A, B, and C can also exist independently in a non-supported form. 3. The method according to claim 1, characterized in that the weight ratio of the metal active component of catalyst A to the active component of catalyst B (in terms of metal tungsten weight) is preferably in the range of 0.05-100 times. 4. The method according to claim 1, characterized in that the weight ratio of the metal active component of catalyst A to the active component of catalyst C (in terms of metal rhenium weight) is preferably within the range of 0.1-100 times. 5. The method according to claim 1, characterized in that: the reaction temperature range is 150-350°C, the preferred reaction temperature is 220-280°C, the preferred hydrogen pressure is 3-10MPa during the reaction, and the preferred reaction time is 30min 3h, the mass ratio of the reaction raw material to the catalyst (based on the mass of the active metal) is 1:1-30000:1. 6. according to the described method of claim 5, it is characterized in that: the mass ratio preferred scope of reaction raw material and catalyzer (in terms of active metal mass) is 3: 1-3000: 1, more preferred scope is 4: 1-1000 : 1. 7. according to the described method of claim 1, it is characterized in that: described cellulose reaction raw material is derived from plant, comprises corn cob, or stalk, and stalk is derived from corn, wheat, cotton, sorghum, soybean, rice, sugarcane, Or from municipal sewage, wood, forestry waste, recycled paper products.