Phosphotungstic acid / metal composite catalyst, preparation method thereof and method for preparing isosorbide from glucose

Abstract

The invention relates to the field of isosorbide preparation, in particular to a phosphotungstic acid / metal composite catalyst, a preparation method thereof and a method for preparing isosorbide from glucose. The phosphotungstic acid / metal composite catalyst contains phosphotungstic acid and transition metal elements, wherein the transition metal element is selected from at least one of an IB group metal element, a VIB group metal element and a VIII B group metal element; relative to 1 g of phosphotungstic acid, the content of transition metal elements in the phosphotungstic acid / metal composite catalyst is 0.0002 to 0.003 mol. The catalyst has good catalytic performance, shows good catalytic activity and selectivity, and has high isosorbide yield, so that the method for directly preparing isosorbide through glucose catalysis has a better market prospect.

Description

Technical Field

[0001] The present invention relates to the field of isosorbide preparation, and more particularly to a phosphotungstic acid / metal composite catalyst, a preparation method thereof, and a method for preparing isosorbide from glucose. Background Art

[0002] Due to the characteristics of renewability, rich resources, high functionalization and environmental friendliness, biomass has currently become a research hotspot in the fields of fine chemicals and new materials. As an important biomass-based derivative chemical, isosorbide is a completely non-toxic green diol, which is not only widely used in the fields of medicine, surfactants and plastic additives, but also has very important significance in the field of new polymer materials. For example, isosorbide is an excellent antihypertensive and diuretic; isosorbide can be used to synthesize surfactants span and tween; it can also be used to synthesize new green plasticizers to replace phthalate plasticizers; isosorbide can be used to modify PET to significantly improve its high-temperature properties and impact resistance by replacing ethylene glycol; in the new material technology of carbonates, as an important raw material to replace bisphenol A with potential health hazards has also shown promise, thereby improving the environmental friendliness of polycarbonates. Therefore, the synthesis technology of isosorbide has attracted much attention in recent years.

[0003] Currently, the reported synthesis technology routes of isosorbide mainly use sorbitol as the raw material and solid acids or liquid acids as catalysts to synthesize by catalytic dehydration method; the liquid acids are mainly concentrated sulfuric acid, benzenesulfonic acid, etc.; although this homogeneous process is relatively mature, the reaction generates various dehydration by-products, the product separation is complex, the equipment is easily corroded, the production cost is increased, and it is not conducive to large-scale industrial application. Solid acids mainly include molecular sieves, ion exchange resins, metal phosphates and heteropolyacids, etc. Due to the advantages of low requirements for equipment materials, relatively simple product separation and catalyst recyclability of solid acid dehydration catalysts, solid acid catalysts have received attention and there is a trend to gradually replace liquid acid catalysts; especially heteropoly compound catalysts, due to their strong acidity, variable structure, good thermal stability, and recyclability, etc., have received extensive attention in the research of replacing liquid acid catalysts. Heteropoly compounds are metal-oxygen cluster compounds formed by cations (such as H + 、Na + etc.), heteroatoms (such as P, Si, Fe, etc.) and coordination (poly) atoms (such as W, Mo, Nb, etc.) according to a certain spatial structure and bridged by oxygen atoms to bridge metal atoms. According to the different ratios of the number of coordination atoms to heteroatoms and the stacking modes, heteropoly compounds have various configurations, among which the Keggin structure and the Dawson structure are the most common.

[0004] For example, Patent CN101691376A discloses a method for preparing isosorbide using a supported heteropolyacid with a Keggin structure as a catalyst. Using sorbitol from a biological source as a raw material, isosorbide is prepared through a dehydration reaction. The selectivity of isosorbide is as high as 75.2%, and the catalyst is easy to separate and recycle. However, considering the raw materials and synthesis process, the current cost of catalytic dehydration of sorbitol to prepare isosorbide is relatively high, resulting in a still high production cost of isosorbide. This is also the main reason why the supported heteropolyacid with a Keggin structure is difficult to promote in downstream applications.

[0005] Considering that the current cost of catalytic dehydration of sorbitol to prepare isosorbide is relatively high, if a process is developed using glucose, which is inexpensive and abundant, as the reaction raw material for preparing isosorbide, and an efficient process is provided to reduce the raw material cost and production cost of preparing isosorbide, it will be beneficial to the popularization and application of isosorbide. However, currently, no highly efficient and selective catalyst has been developed for the process of preparing isosorbide from glucose.

[0006] Therefore, the object of the present invention is to provide a new process using glucose as the reaction raw material for preparing isosorbide, and to provide a novel catalyst for this process, which is suitable for this process and has a high product selectivity, thereby reducing the raw material cost and production cost of preparing isosorbide and promoting the popularization and application of isosorbide. Summary of the Invention

[0007] Aiming at the above technical problems existing in the prior art, the object of the present invention is to provide a phosphotungstic acid / metal composite catalyst, its preparation method, and a method for preparing isosorbide using glucose. This catalyst has both a reduction activity center and an acidic center, and can be applied to the reduction and dehydration reactions of glucose to prepare isosorbide, showing good catalytic performance. Since low-cost raw material glucose is used, and the dual active centers of the catalyst have good synergy, showing good catalytic activity and selectivity, and having a high isosorbide yield, the direct preparation of isosorbide by catalytic reaction of glucose in the present invention has a better market prospect.

[0008] The first aspect of the present invention is to provide a phosphotungstic acid / metal composite catalyst, which contains phosphotungstic acid and a transition metal element; wherein, the transition metal element is selected from at least one of Group IB metal elements, Group VIB metal elements, and Group VIII metal elements;

[0009] Relative to 1 g of phosphotungstic acid, the content of the transition metal element in the phosphotungstic acid / metal composite catalyst is 0.0002 - 0.003 mol, for example, 0.0002, 0.0004, 0.0006, 0.0008, 0.001, 0.0015, 0.002, 0.0025, 0.003 mol, as well as any two numerical values or any interval between any two numerical values.

[0010] In a preferred embodiment of the present invention, relative to 1 g of phosphotungstic acid, the content of the transition metal element in the phosphotungstic acid / metal composite catalyst is 0.0003 - 0.001 mol, for example, 0.0003, 0.0004, 0.0006, 0.0008, 0.001 mol, as well as any two numerical values or any interval of any two numerical values.

[0011] In a preferred embodiment of the present invention, the transition metal element is selected from at least one of copper, nickel, ruthenium, silver, platinum, gold, chromium, molybdenum, and tungsten.

[0012] In a preferred embodiment of the present invention, the transition metal element exists in the form of a transition metal oxide and / or a transition metal simple substance.

[0013] In a preferred embodiment of the present invention, the phosphotungstic acid / metal composite catalyst further contains a carrier.

[0014] According to the present invention, the mass ratio of the phosphotungstic acid to the carrier can be selected within a relatively wide range. In a preferred embodiment of the present invention, the mass ratio of the phosphotungstic acid to the carrier is 1:(2 - 10).

[0015] According to the present invention, the method of loading the above active ingredients on the carrier can be selected within a relatively wide range. In a preferred embodiment of the present invention, the phosphotungstic acid source and the transition metal element source are loaded on the carrier source by the sol - gel method; more preferably,

[0016] The carrier source is selected from at least one of a silicon source, a titanium source, a zirconium source, and an aluminum source capable of forming a gel, preferably a silicon source, and more preferably an orthosilicate.

[0017] According to the present invention, the total weight of the phosphotungstic acid source and the carrier source can be selected within a relatively wide range. In a preferred embodiment of the present invention, the weight ratio of the total weight of the phosphotungstic acid source to the carrier source is 1:(2 - 10).

[0018] According to the present invention, the phosphotungstic acid can be one or more of the following: commercially available phosphotungstic acid (such as Keggin - type H3[PW 12 O 40 ·nH2O, Dawson - type H6P2W 18 O 62 ), and the phosphotungstic acid is obtained by a self - made method. Preferably, the phosphotungstic acid is prepared by the method of the present invention.

[0019] More preferably, the phosphotungstic acid is prepared by the following method:

[0020] React raw materials including a tungsten source, a phosphorus source and an optional inorganic acid, and after purification, phosphotungstic acid is obtained. Preferably, the molar ratio of tungsten element in the tungsten source to phosphorus element in the phosphorus source is (3 - 10):1, preferably (4 - 6):1. The inventors of the present invention found that the phosphotungstic acid / metal composite catalyst obtained by the synergistic cooperation of the phosphotungstic acid obtained by this ratio and the transition metal in the present invention has better catalytic performance, and shows good catalytic activity and selectivity in the reaction of catalytically preparing isosorbide from low-cost raw material glucose, and has a high isosorbide yield.

[0021] In a preferred embodiment of the present invention, the addition amount of the inorganic acid makes the pH of the mixed solution 1 - 3.

[0022] In a preferred embodiment of the present invention, the reaction conditions include: the temperature is 60 - 120 °C, and / or the time is 2 - 5 h.

[0023] In a preferred embodiment of the present invention, the purification method includes: mixing the reaction product mixture with an extraction solvent, and performing extraction and drying steps; preferably, the extraction solvent is selected from at least one of diethyl ether, ethylene glycol dimethyl ether, and ethylene glycol diethyl ether.

[0024] In a preferred embodiment of the present invention, the tungsten source is selected from at least one of tungstic acid and tungstate.

[0025] In a preferred embodiment of the present invention, the phosphorus source is selected from at least one of phosphoric acid and phosphate.

[0026] In a preferred embodiment of the present invention, the inorganic acid is selected from at least one of phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

[0027] The second aspect of the present invention is to provide a preparation method of the phosphotungstic acid / metal composite catalyst described in the first aspect, including the following steps:

[0028] (1) React raw materials including a tungsten source, a phosphorus source and an optional inorganic acid, and after purification, phosphotungstic acid is obtained;

[0029] (2 - 1) Mix the phosphotungstic acid obtained in step (1) and a transition metal source in a solution, preferably mix at 60 - 200 °C for 6 - 16 h, and then dry and calcine to obtain a composite catalyst; or,

[0030] (2 - 2) Mix the phosphotungstic acid obtained in step (1) and a transition metal source in a solution, then mix with an organic solvent and a carrier source to obtain a sol - gel, and then perform heat treatment to obtain a composite catalyst.

[0031] In a preferred embodiment of the present invention, in step (1): the molar ratio of tungsten element in the tungsten source to phosphorus element in the phosphorus source is (3 - 10):1, preferably (4 - 6):1.

[0032] According to the present invention, the addition amount of the inorganic acid in step (1) can be selected within a relatively wide range. In a preferred embodiment of the present invention, the addition amount of the inorganic acid makes the pH of the mixed solution 1 - 3.

[0033] According to the present invention, the reaction conditions in step (1) can be selected within a relatively wide range. In a preferred embodiment of the present invention, the reaction conditions include: the temperature is 60 - 120 °C, and / or the time is 2 - 5 h.

[0034] In a preferred embodiment of the present invention, the purification method includes: mixing the reaction product mixture with an extraction solvent, and performing the steps of extraction and drying; preferably, the extraction solvent is selected from at least one of ether, ethylene glycol dimethyl ether, and ethylene glycol diethyl ether.

[0035] According to the present invention, the tungsten source can be selected within a relatively wide range. In a preferred embodiment of the present invention, the tungsten source is selected from at least one of tungstic acid and tungstate.

[0036] According to the present invention, the phosphorus source can be selected within a relatively wide range. In a preferred embodiment of the present invention, the phosphorus source is selected from at least one of phosphoric acid and phosphate.

[0037] According to the present invention, the inorganic acid can be selected within a relatively wide range. In a preferred embodiment of the present invention, the inorganic acid is selected from at least one of phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

[0038] According to the present invention, the calcination conditions in step (2 - 1) can be selected within a relatively wide range. In a preferred embodiment of the present invention, the calcination conditions in step (2 - 1) include: the temperature is 200 - 500 °C, and / or the time is 3 - 10 h.

[0039] According to the present invention, the dosage of the transition metal source in step (2 - 1) can be selected within a relatively wide range. In a preferred embodiment of the present invention, in step (2 - 1): relative to 1 g of phosphotungstic acid, in terms of the molar amount of the transition metal element, the dosage of the transition metal source is each 0.0002 - 0.003 mol, preferably 0.0003 - 0.001 mol. For example, 0.0003, 0.0004, 0.0006, 0.0008, 0.001 mol, and any two numerical values or any interval of any two numerical values.

[0040] According to the present invention, the dosage of the transition metal source in step (2-2) can be selected within a relatively wide range. In a preferred embodiment of the present invention, in step (2-2): relative to 1 g of phosphotungstic acid, in terms of the molar amount of the transition metal element, the dosage of the transition metal source is each 0.0002 - 0.003 mol, preferably 0.0003 - 0.001 mol. For example, 0.0003, 0.0004, 0.0006, 0.0008, 0.001 mol, as well as any two numerical values or any interval of any two numerical values.

[0041] According to the present invention, the transition metal source can be selected within a relatively wide range. In a preferred embodiment of the present invention, the transition metal source is selected from at least one of nitrates, carbonates, sulfates, chlorides, and acetates of transition metals; preferably at least one of nitrates, sulfates, and chlorides of transition metals.

[0042] According to the present invention, the weight ratio of the phosphotungstic acid obtained in step (1) of step (2-2) to the carrier source can be selected within a relatively wide range. In a preferred embodiment of the present invention, the weight ratio of the phosphotungstic acid obtained in step (1) to the carrier source is 1:(2 - 10).

[0043] According to the present invention, the organic solvent in step (2-2) can be selected within a relatively wide range. In a preferred embodiment of the present invention, the organic solvent is selected from alcohol solvents, preferably at least one of ethanol and isopropanol.

[0044] According to the present invention, the carrier source in step (2-2) can be selected within a relatively wide range. In a preferred embodiment of the present invention, the carrier source is selected from at least one of silicon sources, titanium sources, zirconium sources, and aluminum sources capable of forming gels, preferably a silicon source, and more preferably an orthosilicate.

[0045] According to the present invention, the conditions for heat treatment in step (2-2) can be selected within a relatively wide range. In a preferred embodiment of the present invention, the conditions for heat treatment include: the temperature is 120 - 400 °C, and / or the time is 5 - 24 h.

[0046] In a preferred embodiment of the present invention, the preparation method further includes a step of activating the composite catalyst obtained in step (2-1) and / or step (2-2): Preferably, the activation step includes: contacting the composite catalyst obtained in step (2-1) and / or step (2-2) with hydrogen, activating at 100 - 400 °C for 3 - 8 h, and then cooling by passing a protective gas to obtain the activated catalyst.

[0047] In a preferred embodiment of the present invention, the protective gas is nitrogen and / or an inert gas.

[0048] For the sake of easy understanding, the following description is given by way of example:

[0049] The present invention can use phosphoric acid, phosphates and tungstates as raw materials, preferably control a certain temperature, acidity and time to obtain phosphotungstates with a certain structure. Then, the phosphotungstates are modified by introducing one or more metal elements such as copper, nickel, ruthenium, silver, platinum, gold, chromium, molybdenum, tungsten, etc., to obtain a dual-center catalyst with reduction activity and dehydration activity. The reduction activity and acidity of this catalyst can both be adjusted. Preferably, the catalyst is loaded on a high specific surface area support, and a supported catalyst with higher catalytic performance is obtained.

[0050] Further preferably, for the catalyst preparation method provided by the present invention, phosphotungstic acid and its salts with a certain structure are first prepared, and then a supported catalyst is prepared by the sol-gel method:

[0051] First, phosphoric acid or hydrogen phosphate and tungstate are mixed, the acidity is controlled, and the reaction is carried out at a certain reaction temperature for an appropriate reaction time. Then, solvent extraction is carried out and the oil layer is distilled to obtain phosphotungstic acid with a certain structure.

[0052] Weigh a certain amount of phosphotungstic acid and dissolve it in water. Slowly add a certain amount of nitrate, carbonate, sulfate or acetate solution of copper, nickel, ruthenium, silver, platinum, gold, chromium, molybdenum, tungsten, or a combination thereof under stirring at room temperature. Then, heat to an appropriate temperature, rotary evaporate to remove water, and vacuum dry for a certain time. Place the dried precipitate in a muffle furnace and calcine for a certain time to obtain a phosphotungstate catalyst.

[0053] Then, a supported catalyst is obtained by the sol-gel method. Using orthosilicate as the silicon source, a certain amount of phosphotungstic acid or salt and orthosilicate are mixed, an alcohol solvent and water are added, the acidity and temperature are adjusted, and stirring is carried out for a certain time to form a gel. After washing and drying, the required supported catalyst is obtained.

[0054] It is also possible to prepare a catalyst supported on titanium oxide, zirconium oxide, aluminum oxide or their composite oxides by the sol-gel method.

[0055] Before the catalyst of the present invention is used, the catalyst must be activated.

[0056] The obtained activated phosphotungstic acid and supported catalyst are used for the preparation of isosorbide.

[0057] The third aspect of the present invention is to provide a phosphotungstic acid / metal composite catalyst prepared by the preparation method described in the second aspect.

[0058] The fourth aspect of the present invention is to provide a method for synthesizing isosorbide, which includes the following steps in the presence of the phosphotungstic acid / metal composite catalyst: first, reacting glucose with hydrogen for a hydrogenation reaction, and then subjecting the obtained hydrogenation reaction product to a dehydration reaction;

[0059] The phosphotungstic acid / metal composite catalyst is the phosphotungstic acid / metal composite catalyst described in any one of the first aspect and the third aspect of the claims.

[0060] Preferably, before the hydrogenation reaction, it includes a step of activating the phosphotungstic acid / metal composite catalyst in the presence of hydrogen. Preferably, the activation step includes: contacting the composite catalyst obtained in step (2-1) and / or step (2-2) with hydrogen, activating at 100-400 °C for 3-8 h, and then passing a protective gas to cool down to obtain the activated catalyst.

[0061] According to the present invention, the conditions of the hydrogenation reaction can be selected within a relatively wide range. In a preferred embodiment of the present invention, the conditions of the hydrogenation reaction include: the temperature of the hydrogenation reaction is 80-160 °C, and / or the pressure is 5-50 atm, and / or the time is 3-15 h.

[0062] According to the present invention, the conditions of the dehydration reaction can be selected within a relatively wide range. In a preferred embodiment of the present invention, the conditions of the dehydration reaction include: the temperature of the dehydration reaction is 110-165 °C, and / or the reaction time is 5-15 h, and / or the reaction pressure is 0.04-0.3 atm.

[0063] According to the present invention, the dosage of the phosphotungstic acid / metal composite catalyst can be selected within a relatively wide range. In a preferred embodiment of the present invention, by mass, the dosage of the phosphotungstic acid / metal composite catalyst accounts for 1%-10% of the total mass of the glucose, preferably 2%-5%.

[0064] In a preferred embodiment of the present invention, the synthesis method further includes separating and purifying after the dehydration reaction to obtain purified isosorbide.

[0065] According to the present invention, the purification and separation method can adopt the conventional separation and purification methods in the art. In a preferred embodiment of the present invention, the purification and separation method is distillation and / or crystallization. For example, distillation can be carried out under the conditions of a distillation temperature of 160°C and a vacuum degree of 5 mbar, and then crystallization can be carried out in a mixed solvent of isopropanol and n-hexane. Preferably, the mass ratio of isopropanol to n-hexane is (10-20):1. As an example, the method of distillation and crystallization can be as follows: The reaction solution is filtered, distilled (distillation temperature 160°C, distillation vacuum degree 5 mbar) and crystallized (the crystallization solvent is a mixed solvent of isopropanol and n-hexane (the mass ratio of the two solvents is 15:1), crystallization temperature 20°C), and then dried to obtain the isosorbide product.

[0066] The catalytic reaction route of the catalyst of the present invention is as follows:

[0067]

[0068] As an example, the preferred preparation process of isosorbide is as follows: In the present invention, the reaction raw material is glucose solid or aqueous solution. The temperature of the hydrogenation reaction is 80-160°C, the pressure is 5-50 atm, the time is 3-15 h, the catalyst dosage is 1-10%, and after the reaction is completed, subsequent dehydration reaction is carried out. The dehydration reaction temperature is between 110-165°C, the reaction time is between 5-15 h, the reaction pressure is between 0.04-0.3 atm, and the addition amount of the catalyst is between 1-10% of the reaction raw material. The catalyst prepared by the present invention has both a reduction activity and an acidic double center, and shows different activities and selectivities under different reaction conditions. A certain amount of glucose is added to the reactor, and then the obtained heteropoly compound catalyst is added, hydrogen is introduced, pressurized, stirring is started, heating is carried out, after reacting for a certain time, then depressurized, the temperature and vacuum degree are controlled, and the dehydration reaction is carried out to obtain the target product isosorbide, and then cooled, and the product is separated and purified by distillation and crystallization. The catalyst is recycled many times with stable performance. The obtained product can be widely used in the fields of organic synthesis, new materials and medicine, etc.

[0069] As described above, considering the currently high cost of preparing isosorbide by catalytic dehydration of sorbitol, using glucose, which is inexpensive and abundant, as the reaction raw material can reduce the production cost of isosorbide. The catalyst of the present invention exhibits different activities and selectivities under different reaction conditions. In a hydrogen atmosphere and under high pressure, the catalyst shows strong reducibility, and the reactant glucose is reduced to sorbitol; then under reduced pressure and at a relatively low temperature, a large amount of 1,4-anhydrous products are selectively generated, and at a high temperature, the next dehydration reaction continues to obtain the target product isosorbide, with a reaction yield reaching 75% or even as high as over 81%. The catalytic performance of the catalyst of the present invention is stable and can be reused multiple times. Isosorbide can be widely used in the fields of organic synthesis, new materials, and medicine.

[0070] In summary, the catalyst of the present invention has dual centers of reduction activity and acidity, can be applied to the reduction and dehydration reaction of glucose to prepare isosorbide, and exhibits good catalytic performance; due to the use of low-cost raw material glucose, and the dual active centers of the catalyst have good synergy, showing good catalytic activity and selectivity, and having a high isosorbide yield. Therefore, the direct preparation of isosorbide by catalytic glucose in the present invention has a better market prospect. Detailed implementation mode

[0071] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0072] The following examples and comparative examples are detected by the following methods:

[0073] Detection method for isosorbide purity: Determined by the external standard method of high performance liquid chromatography.

[0074] The calculation method for isosorbide yield is as follows:

[0075] The calculation formulas for glucose conversion rate, isosorbide selectivity and yield are as follows.

[0076]

[0077]

[0078]

[0079] In the formula, n---molar amount of substance (mol); C---conversion rate (%) ; S---selectivity (%) ; Y---yield (%) ; glucose---glucose; isosorbide---isosorbide.

[0080] Preparation Example 1 of Phosphotungstic Acid

[0081] First, add 100 g of phosphoric acid with a concentration of 15 mol / L to a reactor and stir. Then, add an aqueous solution of sodium tungstate with a concentration of 30 mol / L so that the molar ratio of tungsten element to phosphorus element in the reaction solution is 4:1;

[0082] Add a few drops of concentrated hydrochloric acid to make the pH of the mixed solution 1. Heat to 110 °C and keep for 5 hours. Cool to room temperature (25 °C), add the organic solvent ether, stir, let stand for 30 min, take the lower layer solution, then evaporate to remove the solvent and dry to obtain phosphotungstic acid.

[0083] Preparation Example 2 of Phosphotungstic Acid

[0084] First, add 100 g of phosphoric acid with a concentration of 15 mol / L to a reactor and stir. Then, add an aqueous solution of sodium tungstate with a concentration of 30 mol / L so that the molar ratio of tungsten element to phosphorus element in the reaction solution is 3:1;

[0085] Add a few drops of concentrated hydrochloric acid to make the pH of the mixed solution 1. Heat to 110 °C and keep for 5 hours. Cool to room temperature (25 °C), add the organic solvent ether, stir, let stand for 30 min, take the lower layer solution, then evaporate to remove the solvent and dry to obtain phosphotungstic acid.

[0086] Preparation Example 3 of Phosphotungstic Acid

[0087] First, add 100 g of phosphoric acid with a concentration of 15 mol / L to a reactor and stir. Then, add an aqueous solution of sodium tungstate with a concentration of 30 mol / L so that the molar ratio of tungsten element to phosphorus element in the reaction solution is 10:1;

[0088] Add a few drops of concentrated hydrochloric acid to make the pH of the mixed solution 1. Heat to 110 °C and keep for 5 hours. Cool to room temperature (25 °C), add the organic solvent ether, stir, let stand for 30 min, take the lower layer solution, then evaporate to remove the solvent and dry to obtain phosphotungstic acid.

[0089] Catalyst Preparation Example 1

[0090] Weigh 50 g of phosphotungstic acid (Preparation Example 1 of phosphotungstic acid) and dissolve it in water. At room temperature (25 °C), slowly add 350 mL of a Cu(NO3)2 solution with a concentration of 0.1 mol / L under stirring. Then heat to 80 °C and stir for 10 h. Then remove water by rotary evaporation and dry under vacuum. Place the dried precipitate in a muffle furnace and calcine at 260 °C for 5 h to obtain a copper phosphotungstate catalyst.

[0091] Catalyst Preparation Example 2

[0092] Dissolve 50 g of phosphotungstic acid (Preparation Example 1 of phosphotungstic acid) in 100 mL of water with stirring. Dissolve 4.5 g of ruthenium(III) chloride trihydrate in 100 mL of water with stirring. Then add 80 mL of ethanol and 300 mL of tetraethyl orthosilicate, and stir for 12 h. Pour the mixed liquid into a container, seal it, and carry out gelation at room temperature to obtain a uniform and transparent gel. Evaporate the liquid in a water bath, then transfer it to an oven and dry at 100 °C for 24 h. After pulverization, the required supported ruthenium phosphotungstate catalyst is obtained. The content of the carrier is 2 g relative to 1 g of phosphotungstic acid.

[0093] Catalyst Preparation Example 3

[0094] Dissolve 50 g of phosphotungstic acid (Preparation Example 1 of phosphotungstic acid) in 100 mL of water with stirring. Dissolve 3.5 g of silver nitrate in 100 mL of water with stirring. Then add 90 mL of ethanol and 300 mL of tetraethyl orthosilicate, and stir for 12 h. Pour the mixed liquid into a container, seal it, and carry out gelation at room temperature to obtain a uniform and transparent gel. Evaporate the liquid in a water bath, then transfer it to an oven and dry at 100 °C for 24 h. After pulverization, the required supported silver phosphotungstate catalyst is obtained. The content of the carrier is 2 g relative to 1 g of phosphotungstic acid.

[0095] Catalyst Preparation Example 4

[0096] Dissolve 50 g of phosphotungstic acid (Preparation Example 1 of phosphotungstic acid) in 100 mL of water with stirring. Dissolve 6.5 g of copper(II) nitrate in 100 mL of water with stirring. Then add 80 mL of ethanol and 300 mL of tetraethyl orthosilicate, and stir for 12 h. Pour the mixed liquid into a container, seal it, and carry out gelation at room temperature to obtain a uniform and transparent gel. Evaporate the liquid in a water bath, then transfer it to an oven and dry at 100 °C for 24 h. After pulverization, the required supported copper phosphotungstate catalyst is obtained; the content of the carrier is 2 g relative to 1 g of phosphotungstic acid.

[0097] Catalyst Preparation Example 5

[0098] Prepare the catalyst according to the method of Catalyst Preparation Example 4, except that the phosphotungstic acid is replaced with the phosphotungstic acid in Preparation Example 2 of phosphotungstic acid.

[0099] Catalyst Preparation Example 6

[0100] Prepare the catalyst according to the method of Catalyst Preparation Example 4, except that the phosphotungstic acid is replaced with the phosphotungstic acid in Preparation Example 3 of phosphotungstic acid.

[0101] Catalyst Activation Example

[0102] The above examples and comparative examples were all subjected to activation treatment before the preparation of isosorbide:

[0103] Catalyst activation: Place the catalyst in a muffle furnace or a tube furnace, introduce hydrogen, heat to 300 °C, maintain for 6 h, and then cool down by purging with nitrogen to obtain the activated catalyst.

[0104] The catalysts used in the following isosorbide preparation examples and comparative examples are all activated catalysts.

[0105] Isosorbide Preparation Example 1

[0106] Add 100 g of 60% glucose aqueous solution into a high-pressure reactor, add 1.8 g of self-made copper phosphotungstate (Catalyst Preparation Example 1) as the catalyst, displace with hydrogen 3 times, then pressurize to 12 atm, heat to 120 °C, and stir for 4 h. Then evacuate to 0.19 atm, and then raise the temperature to 135 °C. The generated water is evaporated from the reactor in time and discharged through the condenser. After reacting for 7 h, filter while it is hot to remove the catalyst. The obtained filtrate is subjected to vacuum distillation and crystallization treatment to obtain a high-purity isosorbide product with a product purity of 99% and an isosorbide yield of 75.2%.

[0107] Isosorbide Preparation Example 2

[0108] Add 100 g of 60% glucose aqueous solution into a high-pressure reactor, add 2.0 g of self-made ruthenium phosphotungstate (Catalyst Preparation Example 2) as the catalyst, displace with hydrogen 3 times, then pressurize to 15 atm, heat to 130 °C, and stir for 4 h. Then evacuate to 0.1 atm, and then raise the temperature to 135 °C. The generated water is evaporated from the reactor in time and discharged through the condenser. After reacting for 7 h, filter while it is hot to remove the catalyst. The obtained filtrate is subjected to vacuum distillation and crystallization treatment to obtain a high-purity isosorbide product with a product purity of 99% and a yield of 78.3%.

[0109] Isosorbide Preparation Example 3

[0110] Add 100 g of 60% glucose aqueous solution into a high-pressure reactor, add 2.0 g of self-made supported silver phosphotungstate as the catalyst (Catalyst Preparation Example 3), displace with hydrogen 3 times, then pressurize to 20 atm, heat to 130 °C, and stir for 4 h. Then evacuate to 0.1 atm, and then raise the temperature to 140 °C. The generated water is evaporated from the reactor in time and discharged through the condenser. After reacting for 7 h, filter while it is hot to remove the catalyst. The obtained filtrate is subjected to vacuum distillation and crystallization treatment to obtain a high-purity isosorbide product with a purity of 99% and a yield of 81.5%.

[0111] Isosorbide Preparation Example 4

[0112] Prepare the isosorbide product according to the method of Isosorbide Preparation Example 1, except that the catalyst is replaced with the catalyst in Catalyst Preparation Example 4. A high-purity isosorbide product with a purity of 99% and a yield of 80.2% is obtained.

[0113] Isosorbide Preparation Example 5

[0114] The isosorbide product was prepared according to the method of isosorbide preparation example 1, except that the catalyst was replaced by the catalyst in catalyst preparation example 5. A high-purity isosorbide product was obtained with a purity of 99% and a yield of 71.2%.

[0115] Isosorbide Preparation Example 6

[0116] The isosorbide product was prepared according to the method of isosorbide preparation example 1, except that the catalyst was replaced by the catalyst in catalyst preparation example 6. A high-purity isosorbide product was obtained with a purity of 99% and a yield of 69.5%.

[0117] Example 7

[0118] Weigh 50 g of phosphotungstic acid (commercially available from Beijing Bailingwei Technology Co., Ltd., with a molecular formula of H3[PW 12 O 40 ]) was dissolved in water, and 350 mL of 0.1 mol / L Cu(NO3)2 solution was slowly added under stirring at room temperature (25°C), and then heated to 80°C, stirred for 10 h, and then the water was removed by rotary evaporation and vacuum dried. The dried precipitate was placed in a muffle furnace and calcined at 260°C for 5 h to obtain a copper phosphotungstate catalyst.

[0119] After activation, an isosorbide product was prepared according to the method of isosorbide preparation example 1. The isosorbide product was obtained with a purity of 99% and a yield of 63.6%.

[0120] Comparative Example

[0121] First, 100 g of 15 mol / L phosphoric acid was added to the reactor and stirred, and then a 30 mol / L sodium tungstate aqueous solution was added to make the molar ratio of tungsten element to phosphorus element in the reaction solution 1:1;

[0122] Add a few drops of concentrated hydrochloric acid to make the pH of the mixture 1, heat to 110°C, maintain for 5 hours, cool to room temperature (25°C), add organic solvent ether, stir, let stand for 30 minutes, take the lower layer of solution, then evaporate to remove the solvent, and dry to obtain a tungsten-phosphate compound.

[0123] Weigh 50 g of the tungsten-phosphate compound of this comparative example and dissolve it in water. Slowly add 350 mL of 0.1 mol / L Cu(NO3)2 solution at room temperature (25°C) while stirring. Then heat to 80°C and stir for 10 hours. Then, remove water by rotary evaporation and dry in vacuo. Place the dried precipitate in a muffle furnace and calcine at 260°C for 5 hours to obtain a copper phosphotungstate catalyst.

[0124] After activation, isosorbide products were prepared according to the method of Preparation Example 1 of isosorbide. Isosorbide products were obtained with a purity of 99% and a yield of 45.8%.

[0125] It should be noted that the above-described embodiments are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words rather than limiting words. Modifications can be made to the present invention within the scope of the claims of the present invention as provided, and the present invention can be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same functions.

[0126] All publications, patent applications, patents and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0127] When this specification uses prefixes such as "well-known to those skilled in the art", "prior art" or their similar terms to derive materials, substances, methods, steps, devices or components, etc., the objects derived by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become commonly recognized in the art as suitable for similar purposes.

[0128] In the scope disclosed in this application document, the endpoints and any values of the scope are not limited to the exact scope or value. These scopes or values should be understood to include values close to these scopes or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, various technical solutions can be combined with each other to obtain new technical solutions, and this should also be regarded as specifically disclosed herein.

[0129] In the context of this specification, except for the content clearly stated, any matters or things not mentioned directly apply to those known in the art without any change.

[0130] Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby are regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider that the combination is obviously unreasonable.

Claims

1. A phosphotungstic acid / metal composite catalyst, containing phosphotungstic acid and transition metal elements; Among them, The transition metal elements are selected from at least one of the Group IB metal elements, Group VIB metal elements, and Group VIII B metal elements; Relative to 1 g of phosphotungstic acid, the content of the transition metal elements in the phosphotungstic acid / metal composite catalyst is 0.0002 - 0.003 mol.

2. The phosphotungstic acid / metal composite catalyst according to claim 1, wherein: Relative to 1 g of phosphotungstic acid, the content of the transition metal elements in the phosphotungstic acid / metal composite catalyst is 0.0003 - 0.001 mol; and / or, The transition metal elements are selected from at least one of copper, nickel, ruthenium, silver, platinum, gold, chromium, molybdenum, and tungsten; and / or, The transition metal elements exist in the form of transition metal oxides and / or transition metal simple substances.

3. The phosphotungstic acid / metal composite catalyst according to claim 1, wherein: The phosphotungstic acid / metal composite catalyst further contains a carrier; preferably, The mass ratio of the phosphotungstic acid to the carrier is 1:(2 - 10); and / or, The phosphotungstic acid source and the transition metal element source are loaded on the carrier source by the sol-gel method; more preferably, The carrier source is selected from at least one of a silicon source, a titanium source, a zirconium source, and an aluminum source that can form a gel, preferably a silicon source, and further preferably an orthosilicate ester; and / or, The weight ratio of the total weight of the phosphotungstic acid source to the weight of the carrier source is 1:(2 - 10).

4. A preparation method of the phosphotungstic acid / metal composite catalyst according to any one of claims 1 - 3, comprising the following steps: (1) Reacting raw materials including a tungsten source, a phosphorus source, and an optional inorganic acid, and purifying to obtain phosphotungstic acid; (2 - 1) Mixing the phosphotungstic acid obtained in step (1) and the transition metal element in a solution, preferably mixing at 60 - 200 °C for 6 - 16 h, and then drying and calcining to obtain a composite catalyst; or, (2 - 2) Mixing the phosphotungstic acid obtained in step (1) and the transition metal element in a solution, then mixing with an organic solvent and a carrier source to obtain a sol-gel, and then performing heat treatment to obtain a composite catalyst.

5. The preparation method according to claim 4, wherein: In step (1): The molar ratio of the tungsten element in the tungsten source to the phosphorus element in the phosphorus source is (3 - 10):1, preferably (4 - 6):1; and / or, The addition amount of the inorganic acid makes the pH of the mixed solution 1 - 3; and / or, The reaction conditions include: the temperature is 60 - 120 °C, and / or, the time is 2 - 5 h; and / or, The purification method includes: mixing the reaction product mixture with an extraction solvent, and performing extraction and drying steps; preferably, the extraction solvent is selected from at least one of diethyl ether, ethylene glycol dimethyl ether, and ethylene glycol diethyl ether.

6. The preparation method according to claim 4, wherein: The tungsten source is selected from at least one of tungstic acid and tungstate; and / or, The phosphorus source is selected from at least one of phosphoric acid and phosphate; and / or, The inorganic acid is selected from at least one of phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

7. The preparation method according to claim 4, wherein: The calcination conditions in step (2-1) include: the temperature is 200-500 °C, and / or the time is 3-10 h; and / or In steps (2-1) and (2-2): Relative to 1 g of phosphotungstic acid, in terms of the molar amount of the transition metal element, the dosage of the transition metal source is each 0.0002-0.003 mol, preferably 0.0003-0.001 mol; and / or The transition metal source is selected from at least one of nitrates, carbonates, sulfates, chlorides and acetates of transition metals; preferably at least one of nitrates, sulfates and chlorides of transition metals.

8. The preparation method according to claim 4, wherein: In step (2-2): The weight ratio of the phosphotungstic acid obtained in step (1) to the carrier source is 1:(2-10); and / or The organic solvent is selected from alcohol solvents, preferably at least one of ethanol and isopropanol; and / or The carrier source is selected from at least one of silicon sources, titanium sources, zirconium sources, and aluminum sources capable of forming gels, preferably a silicon source, and more preferably an orthosilicate; and / or The heat treatment conditions include: the temperature is 120-400 °C, and / or the time is 5-24 h.

9. The preparation method according to any one of claims 4-8, wherein: It further includes a step of activating the composite catalyst obtained in step (2-1) and / or step (2-2): Preferably, the activation step includes: contacting the composite catalyst obtained in step (2-1) and / or step (2-2) with hydrogen, activating at 100-400 °C for 3-8 h, and then cooling by passing a protective gas to obtain an activated catalyst; More preferably, The protective gas is nitrogen and / or an inert gas.

10. A phosphotungstic acid / metal composite catalyst prepared by the preparation method according to any one of claims 4-9.

11. A method for synthesizing isosorbide, including the steps of: first reacting glucose with hydrogen to carry out a hydrogenation reaction, and then dehydrating the obtained hydrogenation reaction product; The phosphotungstic acid / metal composite catalyst is the phosphotungstic acid / metal composite catalyst according to any one of claims 1-3 and 10; Preferably, Before the hydrogenation reaction, it includes a step of activating the phosphotungstic acid / metal composite catalyst in the presence of hydrogen.

12. The synthesis method according to claim 11, wherein: The conditions of the hydrogenation reaction include: the temperature of the hydrogenation reaction is 80-160 °C, and / or the pressure is 5-50 atm, and / or the time is 3-15 h; and / or The conditions of the dehydration reaction include: the temperature of the dehydration reaction is 110-165 °C, and / or the reaction time is 5-15 h, and / or the reaction pressure is 0.04-0.3 atm; and / or By mass, the dosage of the phosphotungstic acid / metal composite catalyst accounts for 1%-10% of the total mass of the glucose, preferably 2%-5%; and / or The synthesis method further includes separation and purification after the dehydration reaction to obtain purified isosorbide. Preferably, the purification method is distillation and / or crystallization.

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