Method for synthesizing tetraalkoxyethane

Abstract

The invention discloses a method for synthesizing tetraalkoxyethane. The method comprises the following step: in the presence of oxygen-containing gas and a catalyst, carrying out selective conversion reaction on low-carbon alcohol and a biomass raw material to obtain tetraalkoxyethane. The tetraalkoxyethane synthesis method provided by the invention is based on renewable biomass, the raw material source is wide, the reaction process is green and efficient, and the application prospect is wide.

Description

Technical Field

[0001] The invention relates to the field of catalytic chemistry, and mainly to a method for synthesizing tetraalkoxyethane. Background Art

[0002] Tetraalkoxyethane is an important organic synthesis intermediate and can be used as an intermediate for medicines, dyes, agricultural product preservatives, etc. It can be used to blend waste cooking oil or low-quality diesel, can lower the freezing point of diesel, and because it is rich in oxygen, it can ensure the full combustion of diesel. At the same time, tetraalkoxyethane also shows potential as a solvent for lithium battery electrolytes, so it has a wide range of uses.

[0003] The current method for preparing tetraalkoxyethane is: glyoxal and alkyl alcohol are acetalized under the action of an acid catalyst to obtain the obtained product. However, in addition to generating tetraalkoxyethane, the reaction also generates monoacetals, oligomers and cyclic byproducts, which greatly increases the difficulty of separation and purification. At the same time, the acetal reaction is a reversible reaction, water is a byproduct, and the raw material glyoxal itself is also an aqueous solution. In order to increase the yield of the target reactant, it is generally necessary to remove water to pull the reaction balance. Therefore, the production process is complicated to operate, has high energy consumption and high cost.

[0004] CN105503546A discloses a method for generating tetraalkoxyethane from alkyl alcohol and ethylene dichloride carbonate as reaction raw materials. Although the method is simple in process and has a high product yield, the raw material ethylene dichloride carbonate is expensive, and the reaction is prone to produce by-product hydrogen chloride. The collection of the by-product hydrogen chloride leads to the generation of a large amount of chlorine-containing waste salt. The entire production cost is high and there is an environmental pollution problem, and the economic efficiency is poor.

[0005] CN112195481A discloses a method for synthesizing tetramethoxyethane by membrane electrolysis, wherein a mixture of methylal and methanol is used as a raw material in an electrolytic cell with a dense cross-linked anion membrane, and methylal is subjected to membrane electrolysis in an anode chamber and oxidatively coupled to tetramethoxyethane. This method is only applicable to the synthesis of tetramethoxyethane, and other types of tetraalkoxyethane cannot be obtained. In addition, the process also requires the use of strongly alkaline NaOH or KOH, and the material ion membrane is expensive. The method has high requirements for electrodes, and therefore is not suitable for popularization and application at present.

[0006] How to provide a new method for synthesizing tetraalkoxyethane with high yield and safe, economical and environmentally friendly production process is an urgent problem to be solved in the art. Summary of the invention

[0007] In order to solve the problems of complex preparation process operation, high production cost and low yield of tetraalkoxyethane in the prior art, the present invention provides a new method for synthesizing tetraalkoxyethane, which can synthesize tetraalkoxyethane in one pot and has the characteristics of high yield of tetraalkoxyethane, safe, economical and environmentally friendly production process, etc.

[0008] The present invention provides a method for synthesizing tetraalkoxyethane, comprising the following steps:

[0009] In the presence of an oxygen-containing gas and a catalyst, low-carbon alcohols and biomass raw materials undergo a selective conversion reaction to obtain tetraalkoxyethane.

[0010] In the above technical scheme, the general formula of the tetraalkoxyethane is as follows:

[0011] Wherein R is an alkyl group.

[0012] In the above technical solution, R is a saturated straight-chain or branched alkyl group having 1 to 4 carbon atoms.

[0013] In the above technical scheme, the low-carbon alcohol is a saturated straight-chain alcohol or branched alkyl alcohol containing 1 to 4 carbon atoms, specifically at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and isobutanol.

[0014] In the above technical solution, the water content in the low-carbon alcohol is no more than 20% by weight, preferably no more than 10%, and more preferably no more than 5%.

[0015] In the above technical solution, the mass content of the low-carbon alcohol is greater than or equal to 80%.

[0016] In the above technical solution, the biomass can be selected from primary biomass or carbohydrates processed and extracted from primary biomass. The primary biomass includes but is not limited to at least one of cereal crops (wheat, rice, corn, sorghum, etc.), tuber crops (including sweet potatoes, potatoes, etc.), bamboo, wood, straw, konjac, and sugarcane. The carbohydrates processed and extracted from primary biomass include but are not limited to at least one of monosaccharides, oligosaccharides, and polysaccharides. The primary biomass can be real biomass that has been simply pretreated, wherein the simple pretreatment includes but is not limited to at least one of drying, crushing, steam explosion, acid-base treatment, hydrogen peroxide treatment, etc.

[0017] In the above technical scheme, the monosaccharide is specifically but not limited to at least one of tetraose, pentose and hexose. For example, the tetraose may be erythrose and / or threose, the pentose may be at least one of xylose, xylulose, arabinose, ribose and lyxose; the hexose may be at least one of glucose, mannose, galactose, fructose, sorbose and rhamnose. The oligosaccharide is specifically but not limited to at least one of cellobiose, sucrose, maltose, cyclodextrin, raffinose, xylo-oligosaccharide and fructo-oligosaccharide. The polysaccharide is specifically but not limited to at least one of cellulose, hemicellulose and starch.

[0018] In the above technical solution, the catalyst is a molybdenum-based catalyst; wherein the content of molybdenum, calculated as molybdenum, is 0.5% to 96.0% by mass.

[0019] In the above technical solution, the molybdenum-based catalyst is preferably present in the form of at least one of molybdenum-containing oxides, molybdic acid, non-alkali metal molybdates, molybdenum-containing carbides, hydrogen molybdenum bronze, molybdenum-containing heteropolyacids, and molybdenum-containing heteropolyacid salts.

[0020] In the above technical scheme, the molybdenum-containing oxide in the molybdenum-based catalyst may also contain other metals or may not contain them, preferably contains a mixture of other transition metals, specifically selected from at least one of Ti, Zr, V, Nb, W, Mn, Fe, Zn, Cu, Sn, Pb, and Bi; the non-alkali metal molybdate is preferably at least one of ammonium molybdate, barium molybdate, zinc molybdate, tin molybdate, lead molybdate, cobalt molybdate, and bismuth molybdate; the molybdenum-containing heteropolyacid is preferably at least one of phosphomolybdic acid, phosphotungstomolybdic acid, phosphovanadomolybdic acid, silicomolybdic acid, silicotungstomolybdic acid and silicovanadomolybdic acid, and the molybdenum-containing heteropolyacid salt is preferably at least one of phosphomolybdic acid, phosphotungstomolybdic acid, phosphovanadomolybdic acid, silicomolybdic acid, silicotungstomolybdic acid and silicovanadomolybdic acid.

[0021] Furthermore, the catalyst may be a carrier-supported molybdenum-based catalyst, or may be a carrier-free unsupported molybdenum-based catalyst.

[0022] Furthermore, the carrier in the catalyst can be any carrier disclosed in the prior art. As an example, the carrier used in the present invention is selected from one or more of carbonaceous materials, aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, zinc oxide, niobium oxide, vanadium oxide, rare earth oxide, tin oxide, silicon dioxide-alumina, and zeolite, preferably at least one of titanium oxide, zirconium oxide, vanadium oxide, aluminum oxide, and carbonaceous materials; by weight, the mass ratio of the carrier to the molybdenum-containing compound is (51-99): (1-49).

[0023] In the above technical solution, the mass of molybdenum in the catalyst is 0.5% to 80% of the mass of the biomass raw material, preferably 1% to 70%, and more preferably 2% to 70%, by weight.

[0024] In the above technical solution, the mass of the biomass raw material is 0.1% to 20% of the low-carbon alcohol by weight, preferably 0.1% to 15%, and more preferably 0.1% to 8%.

[0025] In the above technical solution, the volume content of oxygen in the oxygen-containing gas is 5% to 100%, preferably 20% to 100%, calculated by volume fraction of the gas.

[0026] In the above technical solution, in the oxygen-containing gas, except for oxygen, the rest is at least one of nitrogen and an inert gas, wherein the inert gas is selected from at least one of argon and helium.

[0027] In the above technical solution, the reaction pressure is 0.1 to 12.0 MPa, preferably 0.1 to 8.0 MPa, and more preferably 0.1 to 5.0 MPa.

[0028] In the above technical solution, the reaction temperature is 50-220°C, preferably 70-200°C, and more preferably 90-180°C.

[0029] In the above technical solution, the reaction time is 0.5 to 120 h, preferably 1 to 96 h, and more preferably 1 to 72 h.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] 1. The present invention creatively provides a brand-new method for preparing tetraalkoxyethane, which uses biomass as raw material to prepare tetraalkoxyethane, which is more environmentally friendly than the toxic glyoxal raw material used in the art, and has lower cost than the expensive ethylene dichloride carbonate raw material. From the perspective of industrialization, the method for preparing tetraalkoxyethane by the present invention is greatly reduced in cost compared to the existing method for synthesizing tetraalkoxyethane, and the raw materials used are widely available and cheap. At the same time, the method also provides a brand-new approach for the resource utilization and high-value utilization of biomass, and has broad application prospects.

[0032] 2. In the method of the present invention, under mild reaction conditions, the yield of tetraalkoxyethane is outstanding; and according to the synthesis method of the present invention, a variety of tetraalkoxyethanes can be prepared, not limited to tetramethoxyethane. In addition, the tetraalkoxyethane product in the synthesis method of the present invention has high selectivity and low impurity content, which is conducive to separation and purification, and also greatly reduces the production cost of tetraalkoxyethane. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0034] The reaction steps for preparing tetraalkoxyethane according to the present invention and the test analysis after the reaction product are as follows: the required catalyst and a certain amount of reactants are added to a 100mL high-pressure reactor, and then the required amount of low-carbon alcohol is added, the reactor is sealed, and then the reaction gas or inert gas is introduced for replacement, and the reaction gas is filled to the target pressure; the temperature is raised to the target temperature and reacted for a certain time, and the temperature is lowered after the reaction is completed. After cooling to room temperature, the solid and the reaction liquid are filtered and separated, and the volume is constant, and then quantified. The liquid phase reaction product is quantitatively determined by gas chromatography, and HP-INNOWAX (60m×0.25mm×0.25μm) chromatographic column and FID are used for detection. Some reactants are silanized and then quantified by gas chromatography, and HP-1ms (30m×0.25mm×0.25μm)) chromatographic column and FID are used for detection.

[0035] The conversion rate of biomass feedstock and the yield of tetraalkoxyethane (based on the carbon number of the reactant) were calculated according to the following formula:

[0036]

[0037]

[0038] [Example 1]

[0039] Preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst: Mix 0.736g ammonium molybdate and 5g water, stir evenly, then add 1.4g ZrO2 carrier to the mixture, stir and soak at room temperature for 10h, dry at room temperature until most of the water has evaporated, continue to dry in a 110℃ oven overnight, and then calcine in a muffle furnace at 500℃ for 3h.

[0040] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.1g of glucose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them into a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, and the temperature is raised to 150°C, and the reaction is reacted for 24 hours. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0041] [Example 2]

[0042] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0043] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of glucose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them into a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, and the temperature is raised to 150°C, and the reaction is reacted for 24h. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0044] [Example 3]

[0045] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0046] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.6g of glucose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, and the temperature is raised to 150°C, and the reaction is allowed to react for 24 hours. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0047] [Example 4]

[0048] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0049] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of fructose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, and the temperature is raised to 150°C, and the reaction is allowed to react for 24 hours. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0050] [Example 5]

[0051] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0052] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of lyxose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. Close the reactor, then introduce oxygen for replacement three times, fill with oxygen to 1.5MPa, heat to 150°C, and react for 24 hours. After the reaction is completed, cool down, filter and separate the solid and the reaction liquid (reaction product) and fix the volume. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0053] [Example 6]

[0054] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0055] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of erythrose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, and the temperature is raised to 150°C, and the reaction is reacted for 24 hours. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0056] [Example 7]

[0057] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0058] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of cellobiose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them into a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. Seal the reactor, then introduce oxygen for replacement three times, fill with oxygen to 1.5MPa, heat to 150°C, and react for 24 hours. After the reaction is completed, cool down, filter and separate the solid and the reaction liquid (reaction product) and make up the volume. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0059] [Example 8]

[0060] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0061] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of β-cyclodextrin and 0.3g of 30% MoO3 / ZrO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. Close the reactor, then introduce oxygen for replacement three times, fill with oxygen to 1.5MPa, heat to 150°C, and react for 24 hours. After the reaction is completed, cool down, filter and separate the solid and the reaction liquid (reaction product) and make up the volume. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0062] [Example 9]

[0063] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0064] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of ball-milled microcrystalline cellulose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, and the temperature is raised to 150°C, and the reaction is allowed to react for 24 hours. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0065] [Example 10]

[0066] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0067] Processing of konjac powder: Wash and peel the fresh konjac corms and cut them into small pieces of about 0.3 cm, then put them into a freeze dryer and dry them for 24 hours. Then put the dried solid pieces into a ball mill for grinding to obtain konjac powder for use.

[0068] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 1.5g konjac powder and 0.3g 30% MoO3 / ZrO2 catalyst and add them into a high pressure reactor (100mL) containing 30mL anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, the temperature is raised to 160°C, and the reaction is reacted for 120 hours. After the reaction is completed, the temperature is lowered, and the solid and the reaction solution (reaction product) are separated by filtration and constant volume. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0069] [Example 11]

[0070] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0071] Straw pretreatment method: cut the corn straw into small pieces of about 1 cm in length, then clean and remove dust, and then dry at 80 degrees and crush to less than 40 mesh; then in a steam explosion reactor, the straw powder and water are high-pressure steamed (240°C), and the valve is quickly opened to reduce the pressure to achieve the explosion of the straw material; the obtained solid is then treated with an alkali-hydrogen peroxide solution of 4% NaOH-1.2% H2O2, and then the solid material is washed with deionized water to neutrality, and then dried at 80°C for 12 hours for use.

[0072] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 1.5g of pretreated straw and 0.3g of 30% MoO3 / ZrO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. Close the reactor, then introduce oxygen for replacement three times, fill with oxygen to 1.5MPa, heat to 160°C, and react for 120 hours. After the reaction is completed, cool down, filter and separate the solid and the reaction liquid (reaction product) and fix the volume. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0073] [Example 12]

[0074] Preparation of hydrogen molybdenum bronze catalyst: 2.0g H2MoO4 was placed in a high-pressure reactor, which was sealed and filled with 6MPa hydrogen. The reaction was carried out at 250°C for 24h. After cooling, the solid was filtered out, and the catalyst was dried in vacuum at room temperature and sealed for storage.

[0075] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of glucose and 0.1g of hydrogen molybdenum bronze catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. Close the reactor, then introduce oxygen for replacement three times, fill with oxygen to 1.5MPa, heat to 150°C, and react for 24h. After the reaction is completed, cool down, filter and separate the solid and the reaction liquid (reaction product) and make up the volume. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0076] [Example 13]

[0077] Cs3P 12 O 40Preparation of the catalyst: 2.0 g of phosphomolybdic acid and 1.0 g of cesium carbonate are dissolved in 30 ml of deionized water respectively. After complete dissolution, the cesium carbonate solution is added dropwise to the phosphomolybdic acid solution under sufficient stirring, gradually precipitated and aged at room temperature for 12 hours; then separated, washed and dried, and finally calcined at 500°C in a muffle furnace for 3 hours.

[0078] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g glucose and 0.5g Cs3PMo 12 O 40 The catalyst was added to a high-pressure reactor (100 mL) containing 30 mL of anhydrous methanol, the reactor was sealed, and then oxygen was introduced three times for replacement, then the oxygen was filled to 1.5 MPa, the temperature was raised to 150 ° C, and the reaction was continued for 24 hours. After the reaction was completed, the temperature was lowered, the solid and the reaction liquid (reaction product) were separated by filtration and the volume was constant. The liquid product was analyzed by gas chromatography, and the biomass conversion rate and the yield of tetraalkoxyethane were calculated according to the above formula. The evaluation results are listed in Table 1.

[0079] [Example 14]

[0080] ZnMoO x -Preparation of V2O5: Dissolve 0.207g zinc nitrate hexahydrate, 0.245g ammonium molybdate and 0.956g ammonium metavanadate in 100ml deionized water, and heat to 80°C while stirring to ensure complete dissolution of the precursor; evaporate the water at 100°C under strong stirring to obtain a solid powder; then dry the solid at 120°C for 12h, and finally calcine it at 500°C in a muffle furnace for 3h.

[0081] The reaction of synthesizing tetraalkoxyethane was carried out in a closed reactor. Weigh 0.3 g glucose and 0.45 g ZnMoO x -V2O5 catalyst was added to a high pressure reactor (100mL) containing 30mL of anhydrous methanol, the reactor was sealed, and then oxygen was introduced for replacement three times, then the oxygen was filled to 1.5MPa, the temperature was raised to 150°C, and the reaction was continued for 24h. After the reaction was completed, the temperature was lowered, the solid and the reaction liquid (reaction product) were separated by filtration and the volume was constant. The liquid product was analyzed by gas chromatography, and the biomass conversion rate and the yield of tetraalkoxyethane were calculated according to the above formula. The evaluation results are listed in Table 1.

[0082] [Example 15]

[0083] SiMo 12 O xPreparation of / Al2O3 catalyst: Mix 0.6g of silicomolybdic acid and 3.0g of water, stir evenly, then add 1.5g of Al2O3 carrier into the mixture, stir and soak at room temperature for 10h, dry at room temperature until most of the water has evaporated, continue to dry in a 110℃ oven overnight, and then calcine in a muffle furnace at 500℃ for 3h.

[0084] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3 g glucose and 0.33 g SiMo 12 O x / Al2O3 catalyst was added to a high pressure reactor (100mL) containing 30mL of anhydrous methanol, the reactor was sealed, and then oxygen was introduced for replacement three times, then the oxygen was filled to 1.5MPa, the temperature was raised to 150°C, and the reaction was continued for 24h. After the reaction was completed, the temperature was lowered, the solid and the reaction liquid (reaction product) were separated by filtration and the volume was constant. The liquid product was analyzed by gas chromatography, and the biomass conversion rate and the yield of tetraalkoxyethane were calculated according to the above formula. The evaluation results are listed in Table 1.

[0085] [Example 16]

[0086] Preparation of Mo2C / C catalyst: 0.613g of ammonium molybdate and 7.5g of water were mixed and stirred evenly, and then 1.5g of activated carbon carrier was added to the mixture. After stirring and impregnating at room temperature for 10h, it was dried at room temperature until most of the water had evaporated, and then dried in an oven at 110°C overnight, and calcined at 800°C for 3h in a nitrogen atmosphere. After cooling, Mo2C / C was obtained.

[0087] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g glucose and 0.33g Mo2C / C catalyst and add them to a high-pressure reactor (100mL) containing 30mL anhydrous methanol. Close the reactor, then introduce oxygen for replacement three times, fill with oxygen to 1.5MPa, heat to 150°C, and react for 24h. After the reaction is completed, cool down, filter and separate the solid and the reaction liquid (reaction product) and fix the volume. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0088] [Example 17]

[0089] Preparation of 10% (mass fraction) MoO3 / SiO2 catalyst: Mix 0.245g ammonium molybdate and 8.0g water, stir evenly, then add 1.8g SiO2 carrier to the mixture, stir and soak at room temperature for 10h, dry at room temperature until most of the water has evaporated, continue to dry in a 110℃ oven overnight, and then calcine in a muffle furnace at 500℃ for 3h.

[0090] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of glucose and 0.2g of 10% MoO3 / SiO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, the temperature is raised to 150°C, and the reaction is carried out for 24h. After the reaction is completed, the temperature is lowered, the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 1.

[0091] [Comparative Example 1]

[0092] The reaction was carried out in a closed reactor. Weigh 0.3g of glucose and add it to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor was sealed, and then oxygen was introduced three times for replacement, and then the oxygen was filled to 1.5MPa, and the temperature was raised to 150°C for reaction for 24h. After the reaction was completed, the temperature was lowered, and after constant volume, the liquid phase product was analyzed by gas chromatography, and the biomass conversion rate and tetraalkoxyethane yield were calculated according to the above formula. The evaluation results are listed in Table 1.

[0093] [Comparative Example 2]

[0094] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0095] The reaction was carried out in a closed reactor. No biomass raw materials were added. 0.3 g of 30% MoO3 / ZrO2 catalyst was weighed and added to a high-pressure reactor (100 mL) containing 30 mL of anhydrous methanol. The reactor was sealed, and then oxygen was introduced for replacement three times, and then the oxygen was filled to 1.5 MPa, and the temperature was raised to 150°C for reaction for 24 hours. After the reaction was completed, the temperature was lowered, the solid and the reaction liquid (reaction product) were separated by filtration and the volume was fixed. The liquid product was analyzed by gas chromatography, and no tetraalkoxyethane was detected. The evaluation results are listed in Table 1.

[0096] [Comparative Example 3]

[0097] The reaction was carried out in a closed reactor. Weigh 0.3g glucose and 0.075g Na2MoO4 and add them to a high-pressure reactor (100mL) containing 30mL anhydrous methanol. The reactor was sealed, and then oxygen was introduced three times for replacement, and then the oxygen was filled to 1.5MPa, and the temperature was raised to 150°C for reaction for 24h. After the reaction was completed, the temperature was lowered, and after constant volume, the liquid phase product was analyzed by gas chromatography, and the biomass conversion rate and tetraalkoxyethane yield were calculated according to the above formula. The evaluation results are listed in Table 1.

[0098] [Comparative Example 4]

[0099] The reaction is carried out in a closed reactor. Weigh 0.3g of glucose, 0.3g of ZrO2 and 0.3g of SiO2 and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced three times for replacement, and then the oxygen is filled to 1.5MPa, the temperature is raised to 150°C, and the reaction is carried out for 24h. After the reaction is completed, the temperature is lowered, the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the yield of tetraalkoxyethane are calculated according to the above formula. The evaluation results are listed in Table 1.

[0100] [Comparative Example 5]

[0101] Preparation of WO3 catalyst: Weigh 2.0g of ammonium metatungstate and calcine it at 500℃ in a muffle furnace for 3h.

[0102] The reaction was carried out in a closed reactor. Weigh 0.3g of glucose and 0.5g of WO3 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor was sealed, and then oxygen was introduced three times for replacement, and then the oxygen was filled to 1.5MPa, the temperature was raised to 150°C, and the reaction was carried out for 24h. After the reaction was completed, the temperature was lowered, the solid and the reaction liquid (reaction product) were separated by filtration and the volume was fixed. The liquid product was analyzed by gas chromatography, and the biomass conversion rate and the yield of tetraalkoxyethane were calculated according to the above formula. The evaluation results are listed in Table 1.

[0103] [Comparative Example 6]

[0104] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0105] The reaction is carried out in a closed reactor. Weigh 0.3g of sorbitol and 0.3g of 30% MoO3 / ZrO2 catalyst and add them to a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5MPa, and the temperature is raised to 150°C, and the reaction is allowed to react for 24h. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and the volume is fixed. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the yield of tetraalkoxyethane are calculated according to the above formula. The evaluation results are listed in Table 1.

[0106] Table 1

[0107]

[0108]

[0109] Table 1 Note: Reaction conditions: 30 mL anhydrous methanol, 1.5 MPa O2, 150°C, 24 h; wherein Example 10 and Example 11 were 160°C, 120 h.

[0110] [Examples 18-25]

[0111] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0112] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of mannose and 0.3g of 30% MoO3 / ZrO2 and add them to a high-pressure reactor (100 mL) containing 30 mL of different solvents. The reactor is sealed, and then oxygen is introduced for replacement three times, and then the oxygen is filled to 1.5 MPa, the temperature is raised to 150°C, and the reaction is reacted for 24 hours. After the reaction is completed, the temperature is lowered, the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the yield of tetraalkoxyethane are calculated according to the above formula. Examples 18-25 are for changing the solvent of the reaction, and the evaluation results are listed in Table 2.

[0113] Table 2

[0114]

[0115]

[0116] Notes to Table 2: Reaction conditions: 0.3 g mannose, 30 mL solvent (including water), 0.3 g 30% MoO3 / ZrO2 catalyst, 1.5 MPa O2, 150°C, 24 h.

[0117] [Examples 26-35]

[0118] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0119] The reaction of synthesizing tetramethylethylene is carried out in a closed reactor. Weigh 0.3g of glucose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them into a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then the reaction gas is introduced and replaced three times, and then the reaction gas is filled to the target pressure, and then the temperature is raised for reaction for a certain time. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and constant volume. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the yield of tetraalkoxyethane are calculated according to the above formula. In Examples 26-35, the gas composition, pressure, reaction temperature and reaction time are changed, and the evaluation results are listed in Table 3.

[0120] [Comparative Example 7]

[0121] The preparation of 30% (mass fraction) MoO3 / ZrO2 catalyst is the same as that in Example 1.

[0122] The reaction of synthesizing tetraalkoxyethane is carried out in a closed reactor. Weigh 0.3g of glucose and 0.3g of 30% MoO3 / ZrO2 catalyst and add them into a high-pressure reactor (100mL) containing 30mL of anhydrous methanol. The reactor is sealed, and then nitrogen is introduced for replacement three times, and then filled with nitrogen to 3.0MPa, heated to 150°C, and reacted for 48h. After the reaction is completed, the temperature is lowered, and the solid and the reaction liquid (reaction product) are separated by filtration and the volume is constant. The liquid product is analyzed by gas chromatography, and the biomass conversion rate and the tetraalkoxyethane yield are calculated according to the above formula. The evaluation results are listed in Table 3.

[0123] Table 3

[0124]

[0125]

[0126] Table 3 Note: Reaction conditions: 0.3 g glucose, 30 mL anhydrous methanol, 0.3 g 30% MoO3 / ZrO2 catalyst.

[0127] The embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may 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.

Claims

1. A method for synthesizing tetraalkoxyethane, comprising the steps of: In the presence of an oxygen-containing gas and a catalyst, low-carbon alcohols and biomass raw materials undergo a selective conversion reaction to obtain tetraalkoxyethane.

2. The method according to claim 1, characterized in that: The general formula of the tetraalkoxyethane is as follows: Wherein R is an alkyl group, preferably, R is a saturated straight-chain or branched alkyl group having 1 to 4 carbon atoms.

3. The method according to claim 1, characterized in that The low-carbon alcohol is a saturated straight-chain alcohol or branched alkyl alcohol containing 1 to 4 carbon atoms, preferably at least one selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and isobutanol.

4. The method according to claim 1, characterized in that: In the low-carbon alcohol, water does not exceed 20% by weight.

5. The method according to claim 1, characterized in that The biomass is selected from raw biomass or carbohydrates extracted from raw biomass; Preferably, the primary biomass is selected from at least one of cereal crops, tuber crops, bamboo, wood, straw, konjac, and sugarcane; Preferably, the carbohydrate extracted from the native biomass is selected from at least one of monosaccharides, oligosaccharides and polysaccharides.

6. The method according to claim 5, characterized in that The monosaccharide is selected from at least one of tetrasaccharides, pentoses, and hexoses; the oligosaccharides are selected from at least one of cellobiose, sucrose, maltose, cyclodextrin, raffinose, xylo-oligosaccharides, and fructose-type oligosaccharides; and the polysaccharide is selected from at least one of cellulose, hemicellulose, and starch.

7. The method according to claim 1, characterized in that The catalyst is a molybdenum-based catalyst, wherein the content of molybdenum, calculated as molybdenum, is 0.5% to 96.0% by mass.

8. The method according to claim 7, characterized in that The molybdenum-based catalyst exists in the form of at least one of molybdenum-containing oxides, molybdic acid, non-alkali metal molybdates, molybdenum-containing carbides, hydrogen molybdenum bronze, molybdenum-containing heteropolyacids, and molybdenum-containing heteropolyacid salts.

9. The method according to claim 1, characterized in that: The mass of molybdenum in the catalyst is 0.5% to 80% of the mass of the biomass raw material by weight; optionally, the mass of the biomass raw material is 0.1% to 20% of the low-carbon alcohol by weight.

10. The method according to claim 1, characterized in that Calculated by gas volume fraction, the volume content of oxygen in the oxygen-containing gas is 5% to 100%.

11. The method according to claim 1, characterized in that: The reaction pressure is 0.1 to 12.0 MPa; optionally, the reaction temperature is 50 to 220° C.; optionally, the reaction time is 0.5 to 120 h.

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