128 results about "Dimethyl oxalate" patented technology

The invention discloses an oxamide preparation tail gas treatment device which comprises a methanol absorption section, a methanol condensation section, an ammonia absorption section and an ammonia absorption raw material preparation section which are sequentially arranged from top to bottom, methanol in gas is absorbed by the methanol absorption section through desalted water, and ammonia in the gas is absorbed by the ammonia absorption section through a methanol solution of dimethyl oxalate. The method comprises the following steps: absorbing unreacted ammonia by using dimethyl oxalate, generating oxamide, returning the oxamide to an oxamide synthesis reactor, condensing methanol steam without ammonia so as to reduce methanol brought out by nitrogen, washing tail gas by using a circulating aqueous solution and desalted water, discharging the tail gas after reaching the standard, and feeding the aqueous solution containing methanol to a sewage treatment device to supplement a carbon source. According to the method, steam does not need to be consumed, only a small amount of cooling water or chilled water needs to be consumed, ammonia in the tail gas is absorbed through reaction of dimethyl oxalate needed in the oxamide production process and ammonia in the tail gas, then methanol in the tail gas is condensed and then returns to a reaction system, and therefore recycling of the ammonia and the methanol is achieved.

The present invention discloses a device and method for producing oxalamide, and relates to the field of chemical production. The method for producing oxalamide provided by the present invention specifically comprises: mixing a methanol solution of liquid ammonia and a methanol solution of dimethyl oxalate to undergo an ammonolysis reaction, flashing, filtering, and drying the first slurry after the reaction to obtain solid oxalamide, refining the liquid phase obtained by solid-liquid separation of the first slurry to obtain byproduct methanol, and washing and absorbing ammonia in the tail gas with dimethyl oxalate and returning to the reaction system. In the process of oxalamide production, the present invention utilizes dimethyl oxalate to react with ammonia in the mixed gas generated during the reaction, and the obtained product continues to undergo subsequent ammonolysis reaction, thereby improving the utilization rate of the reaction materials; at the same time, a condenser is not used to condense ammonia and methanol before separation of alcohol and ammonia, thereby saving condensation equipment and cooling water, reducing production costs, and facilitating industrial production.

The invention discloses a system and method for directly preparing battery-grade ferrous oxalate based on dimethyl oxalate, and the system comprises a rectifying tower which is used for carrying out hydrolysis reaction on dimethyl oxalate and discharging a hydrolysis solution through a liquid phase outlet; the decolorizing kettle is used for decolorizing the hydrolysis solution; the precipitation reaction kettle is used for carrying out mixed reaction and aging on the hydrolysis solution and ferric salt; the product recovery unit is connected with the precipitation reaction kettle and is used for separating and recovering reaction products to obtain battery-grade ferrous oxalate. According to the method, the hydrolysis solution of the dimethyl oxalate and the iron salt are directly mixed for precipitation reaction to prepare the battery-grade ferrous oxalate, high-energy-consumption steps such as crystallization and drying in the oxalic acid solid production process are reduced, meanwhile, the step of dissolving the solid oxalic acid is not needed, the heating energy consumption needed in the dissolving process is reduced, and the production efficiency is improved. The production energy consumption is greatly reduced, the production equipment and process are reduced, the cost is reduced, and the product yield is favorably improved.

The utility model belongs to the technical field of oxalate storage, and particularly relates to a harmless discharging device for volatile organic gas in a dimethyl oxalate storage tank, which comprises a storage tank and a liquid seal tank, the top end of the storage tank is connected with a discharging pipe, and a pressure transmitter for detecting air pressure in the tank is fixedly mounted on the storage tank. A regulating valve I in signal connection with the pressure transmitter is mounted on the discharge pipe, one end, far away from the storage tank, of the discharge pipe extends into the liquid seal tank and is positioned below the liquid level in the liquid seal tank, methanol is contained in the liquid seal tank, and the top end of the liquid seal tank is connected with a tail gas pipe. According to the utility model, organic matter gas in the storage tank is discharged into the liquid seal tank and is washed and dissolved by methanol, so that organic matters are prevented from being discharged into the atmosphere, zero emission of harmful substances is realized, and the device is environment-friendly.

The present invention discloses a method for removing coking substances from a hydrogenation catalyst for dimethyl oxalate. The steps are as follows: First, a mixed reagent composed of 70% - 90% tetrahydrofuran, 5% - 20% ethylene glycol monomethyl ether, and 5% - 20% methanol is used as a solvent to dissolve and elute the coking substances aggregated on the hydrogenation catalyst; then, an inert atmosphere containing tetrahydrofuran, methanol, and water is used for purging to remove the high-boiling esters and organic acids adsorbed on the catalyst, and then an inert atmosphere containing tetrahydrofuran and methanol is used for purging to remove the high-boiling alcohols adsorbed on the catalyst, so as to achieve the removal of the coking substances. This method can remove the coking substances on the hydrogenation catalyst for dimethyl oxalate, restore the activity lost due to the catalyst being covered by the coking substances, thereby greatly extending the service life of the catalyst; the method is simple, the cost is low, and the effect is good.

The application discloses a catalyst for preparing methyl acetate or ethanol by hydrogenation of dimethyl oxalate and a preparation method thereof. The catalyst comprises an active component, an auxiliary component and a carrier. The active component is a single substance or an oxide of Cu, the auxiliary component is a single substance or an oxide of W, the high active site is a Cu-W alloy interface and single Cu and W metals, and the carrier is one or more than two of silicon dioxide, aluminum oxide, zirconium oxide, zinc oxide, magnesium oxide and cerium oxide. The copper-tungsten alloy catalyst provided by the application has the advantages of structural stability, high mechanical strength, good heat conduction performance, high substrate conversion rate and high product selectivity. The preparation method is simple in steps, easy in raw material acquisition, low in cost, green in pollution, good in preparation repeatability and easy in scale production. The catalyst has extremely high stability and catalytic activity in the reaction of preparing methyl acetate or ethanol by hydrogenation of dimethyl oxalate, high ethanol or methyl acetate yield and high active component utilization rate.

The application discloses a triazine ring synthesis method, and belongs to the technical field of medical intermediate synthesis. The method is characterized in that 2-methylaminothiourea and dimethyl oxalate are used as raw materials, a nanometer catalyst of scandium triflate (Sc(OTf)3) or ytterbium triflate (Yb(OTf)3) is loaded on magnetic Fe3O4@SiO2, a cyclization reaction is carried out in an organic solvent, the catalyst is separated and recovered through an external magnetic field after the reaction is completed, and high-purity triazine rings are obtained through acidification, crystallization and drying of the reaction liquid. The catalyst has the advantages of high specific surface area, high catalytic activity, easy magnetic separation and recovery, and can be reused more than 6 times. The product yield can reach 93% to 96%, and the purity is greater than or equal to 99.6%. The method realizes green, efficient and low-cost synthesis of triazine rings.

The invention belongs to the technical field of coal ethylene glycol, and particularly relates to a process and a device for finely removing impurities from carbon monoxide after cryogenic separation of synthesis gas, the device comprises an impurity removal device, the impurity removal device comprises a desulfurization tank, a dechlorination tank and a decarbonylation tank which are sequentially connected in series, or an adsorption tower which is sequentially filled with desulfurization, dechlorination and decarbonylation adsorbents; the impurity removal device is arranged to remove trace hydrogen sulfide, hydrogen chloride, carbonyl iron and carbonyl nickel in CO after cryogenic separation, so that ppb-level removal of impurities in CO is realized, poisoning of a downstream dimethyl oxalate (DMO) synthesis catalyst is avoided, the service life of the catalyst is prolonged, the production cost of an enterprise is reduced, and the operation stability of the device is improved.

The application discloses a kind of molecular sieve supported silver monatomic catalyst and its preparation method and application.The catalyst is with molecular sieve as carrier, by silver precursor salt aqueous solution is impregnated to molecular sieve, after drying and with carbon powder mixing, again be placed in joule heat in-situ heating device, at 600 DEG C~1200 DEG C high temperature pyrolysis 5~8 seconds preparation;Wherein silver element mass content is 0.2 wt%~3 wt%.The catalyst prepared by the application realizes that silver monatomic atom is highly dispersed on molecular sieve, and metal utilization rate reaches 100%.The catalyst is applied to oxalic acid dimethyl ester electrocatalytic reduction coupling preparation tartaric acid dimethyl ester reaction, and excellent catalytic performance is shown: at optimum potential, target product tartaric acid dimethyl ester selectivity is as high as 95.3%, faraday efficiency reaches 82.9%, conversion frequency reaches 1880 h ‑1 , and has excellent long-term electrochemical stability.

The invention discloses a copper-based catalyst which comprises a carrier and an active component, and the carrier is silicon nitride; the active component is Cu monatomic, and the Cu monatomic is anchored on the surface of the silicon nitride through a Cu-N bond. The invention also discloses a preparation method of the copper-based catalyst and application of the copper-based catalyst in catalyzing selective hydrogenation of dimethyl oxalate to prepare methyl glycolate.

The invention provides a method and system for preparing dimethyl carbonate through dimethyl oxalate decarbonylation, and the method comprises the following steps: dimethyl oxalate is subjected to decarbonylation reaction in a reactor, and a gas phase product and a first liquid phase product are respectively obtained from the decarbonylation reactor: the first liquid phase product enters a dimethyl carbonate product tower; cooling the gas-phase product, carrying out gas-liquid separation to obtain a gas-phase material and a second liquid-phase product, and feeding the gas-phase material and the second liquid-phase product into the carbonate product tower; absorbing by-products containing carbon dioxide and dimethyl ether by the gas-phase material through dimethyl carbonate, and desorbing and removing by-products containing carbon dioxide and dimethyl ether by the discharged liquid-phase absorption material in a desorption tower. According to the method, a separate discharging mode is adopted, condensate of a liquid-phase product and condensate of a gas-phase product are treated at the same time through the dimethyl carbonate product tower, the process is simple, and energy consumption is low; dimethyl carbonate is adopted as an absorbent, carbon dioxide and dimethyl ether in carbon monoxide product gas can be effectively separated, the process is simple, and energy consumption is low.

The invention relates to a method for generating dimethyl carbonate by decarbonylation of dimethyl oxalate, which comprises the following steps: dissolving dimethyl oxalate in a solvent to prepare a solution, adding a catalyst, and carrying out decarbonylation reaction to obtain dimethyl carbonate, the catalyst comprises a main catalyst and a cocatalyst, the main catalyst is alkoxide of alkali metal, and the cocatalyst is one or more of pyridine, acetone or triethylamine. According to the method, an alkoxide decarbonylation catalyst system of a single alkali metal is changed into a multi-element catalyst system by adding the auxiliary agent, so that the liquid-phase decarbonylation reaction can be carried out at low temperature and low pressure, the reaction condition is milder, the equipment cost and energy consumption of the reaction are reduced, and the catalyst can be recycled for multiple times and has good economic benefits.

The invention discloses a system and method for recycling high-temperature condensate from ethylene glycol synthesis, comprising the following steps: S1, dividing the steam condensate generated by the ethylene glycol synthesis system into two parts, one part preheating the dimethyl oxalate from the dimethyl oxalate buffer tank to a first temperature, and the other part preheating the boiler feed water to a second temperature; S2, transporting the steam condensate after preheating the dimethyl oxalate and the boiler feed water to the condensate main pipe. In the present invention, the steam condensate generated by synthesizing ethylene glycol is used to preheat the dimethyl oxalate and the boiler feed water, which, on the one hand, reduces the use of high-grade steam when 3.5MpaG steam is used to preheat the dimethyl oxalate and the boiler feed water in the prior art, increases the amount of byproducts of 0.8MPa steam, and achieves the purpose of recovering high-grade latent heat from low-grade sensible heat; on the other hand, the heat of the steam condensate is recovered in the form of material heat exchange, and the temperature of the condensate can be finally reduced, and all the heat is recovered, which is superior to the market ORC and condensate refrigeration technology, and has low investment costs and high investment returns.

The invention discloses an ammonia-alcohol separation device which comprises a methanol absorption section, a methanol condensation extraction section, an ammonia absorption section and an ammonia absorption raw material preparation section which are sequentially arranged from top to bottom, the methanol absorption section absorbs methanol in gas through desalted water, and methanol extracted from the methanol condensation extraction section is sent to a dimethyl oxalate synthesis device; the ammonia absorption section is used for absorbing ammonia in the gas through a methanol solution of dimethyl oxalate. The device further comprises a dimethyl oxalate rectification device and an oxamide synthesis device. The chemical reaction in the oxamide production process is used for replacing rectification and washing procedures in the prior art, and complete conversion of ammonia, internal circulation of methyl alcohol in the dimethyl oxalate synthesis and oxamide co-production device and effective utilization of low-level heat energy of dimethyl oxalate are achieved. The invention also discloses a method for co-production of dimethyl oxalate and oxamide by using the ammonia-alcohol separation device.

The utility model relates to the field of a dimethyl oxalate synthesis process, in particular to a nitric acid feeding line and dimethyl oxalate production equipment, an original nitric acid liquid inlet subline is cancelled, and a nitric acid boundary valve is arranged at the output end of a nitric acid feeding system to control the flow of nitric acid entering a specific area or system, so that the nitric acid is ensured to flow in a specified range; it is ensured that nitric acid can stably and continuously enter the next link through a nitric acid feeding valve; through the arrangement of the nitric acid drainage regulating valve and the check valve behind the nitric acid feeding valve, after nitric acid supplementing is stopped, the nitric acid in the pipeline is released through the nitric acid drainage regulating valve, nitric acid accumulated liquid stored in the pipeline is avoided, and therefore the situation that the nitric acid flows backwards and reacts with liquid stored in the pipeline is doubly avoided; and the safety of the pipeline is further improved. The problem that the accident risk is high due to the fact that nitric acid feed of an existing nitric acid reduction tower accumulates in a pipeline and reacts with alcohol-containing liquid of a methyl nitrite regeneration tower reversely into the nitric acid pipeline is solved.

The invention belongs to the technical field of NO gas preparation in the production process of coal ethylene glycol devices, and discloses a start-up method of an NO gas production device in coal ethylene glycol, which comprises the following steps: step 1): preparing materials; according to the driving method disclosed by the invention, key process indexes such as nitric acid dropping speed, pressure, temperature and NO gas flow are strictly controlled in the whole driving process, so that severe reaction and overpressure safety accidents are prevented, and the gas quantity required by a downstream dimethyl oxalate synthesis unit is stably supplied.

The present application relates to a kind of preparation methods and systems of electronic grade dimethyl carbonate prepared from dimethyl oxalate, the method comprises the following steps: dimethyl oxalate is preheated and sent into decarboxylation reactor to carry out decarboxylation reaction, carbon monoxide, dimethyl carbonate and other light components are extracted from the top of decarboxylation reactor, and heavy components are extracted from the bottom of decarboxylation reactor;Carbon monoxide, dimethyl carbonate and other light components extracted are separated after gas-liquid, and liquid phase dimethyl carbonate is sent into rectifying column to carry out rectification purification;Electronic grade dimethyl carbonate product is obtained by crystallization purification in refrigeration crystallization device after rectification, and crystallization mother liquor returns rectifying column;Decarboxylation reactor is three-stage reaction tower, and rectifying section, reaction section, stripping section are sequentially from top to bottom.The present application is completely reacted by the design of three-stage decarboxylation reactor;Heavy components generated are extracted in real time, and catalyst stability is high;Electronic grade DMC is prepared by using rectifying column coupled with crystallization tower, and the yield of DMC is significantly improved.

The invention relates to a synthesis method of dimethyl oxalate, and mainly solves the technical problems of high reaction hot spot temperature, poor dimethyl oxalate selectivity and low space time yield in the prior art. According to the technical scheme, carbon monoxide, nitrogen and methyl nitrite (MN) are used as raw materials, and under the conditions that the inlet temperature is 70-100 DEG C, the volume space velocity is 1000-5000h <-1 >, the CO molar concentration is 10-40%, the CO / MN molar ratio is 1.0-3.0 and the reaction pressure is 0.05-2.0 Mpa, the raw materials pass through a Pd catalyst diluted by small balls with low specific surface area, large aperture and low acid content, the hot-spot temperature of a bed is lower than 125 DEG C, and the reaction is carried out for 1-2 hours, so that the methyl nitrite (MN) is obtained. According to the technical scheme, the problems are well solved, the selectivity of the dimethyl oxalate is larger than 98% in the long-time operation process, the space time yield of the dimethyl oxalate is larger than 750 g / (L.h), and the method can be used for industrial production of synthesizing the dimethyl oxalate through oxidative coupling of carbon monoxide.

The invention discloses a filling method for retarding coking of a hydrogenation catalyst and reducing basic pressure difference of a reactor, which comprises the following steps: an inert material is selected according to the size and bulk density of the hydrogenation catalyst, and the inert material comprises at least one of a Raschig ring, a Pall ring and an inert ceramic ball; calculating the ratio of the inert material to the hydrogenation catalyst, and mixing the inert material with the hydrogenation catalyst according to the ratio; and filling the mixed catalyst mixture into a tube nest. The inert material is used for diluting the active center of the catalyst, dispersing reaction heat and reducing the accumulation of heat at the upper part of the tube nest, so that the reaction intensity is actively reduced, the coking speed is directly slowed down, the basic pressure difference of the reactor is reduced, and the problems that the catalyst is easy to coke and the bed resistance is increased in the process of preparing ethylene glycol by hydrogenation of dimethyl oxalate are effectively solved; reaction conditions are optimized from a filling source, and the service life of the catalyst is prolonged.

The invention discloses a synthetic method of 1, 2, 4-triazole-3-carboxylic acid methyl ester, and belongs to the field of organic synthesis. The preparation method comprises the following steps: by taking formamidine acetate, hydrazine hydrate and dimethyl oxalate as raw materials, carrying out one-pot reaction to obtain the 1, 2, 4-triazole-3-carboxylic acid methyl ester. Compared with the prior art, the method has the advantages of short synthesis process route, short reaction time and simplicity in operation; and the synthesis process is few in three wastes, environment-friendly and green. Meanwhile, the synthesis process is safe and reliable, reaction conditions are mild, and dangerous processes such as diazotization and desulfurization are not involved.

The invention relates to preparation and application of a catalyst, in particular to a preparation method of a silver-based porous boron nitride catalyst, and the catalyst prepared by the method is applied to the field of dimethyl oxalate hydrogenation and is used for preparing methyl glycolate. The preparation method comprises the following steps: carrying out ultrasonic treatment on porous boron nitride in water to form a boron nitride suspension, dissolving various metal salt precursors required for preparing the catalyst, adding a proper amount of ammonia water to form a complex after the metal salt precursors are completely dissolved in water, dropwise adding the obtained complex into the boron nitride suspension, heating in a water bath, and carrying out vacuum drying to obtain the boron nitride catalyst. The method is simple in preparation and good in process repeatability, metal silver is highly dispersed in porous boron nitride through an ammonia distillation method, and under the reaction conditions that the temperature is 200 DEG C, the pressure is 2.5 Mpa, H2 / DMO is 80 and WHSV is 0.625 h <-1 >, the dimethyl oxalate conversion rate reaches 99%, and the methyl glycolate selectivity can reach 95%.

The invention relates to the technical field of organic chemical synthesis, in particular to a catalyst and a process for preparing methyl glycolate and co-producing methyl formate through methanol dehydrogenation coupling oxalate hydrogenation, which comprises the following steps: S1) providing a coal-to-ethylene glycol device which comprises a methanol rectifying tower, a DMO synthesis system, a DMO refining system, a DMO hydrogenation reactor and a condensing system; s2) taking methanol extracted from a methanol rectifying tower as a raw material, and carrying out anaerobic dehydrogenation reaction under the action of the catalyst in any one of claims 1-2 or the catalyst prepared by the preparation method in claim 3 to obtain methyl formate, H2 and CO; and S3) by taking dimethyl oxalate extracted from a DMO refining system as a raw material, carrying out hydrogenation reaction under the action of the catalyst in any one of claims 4-5 or the catalyst prepared by the preparation method in claim 6 to obtain methyl glycolate and methanol.

The invention discloses a method for increasing the load of a dimethyl oxalate synthesis system and reducing the content of methyl nitrite in the system, and the method comprises the step of arranging a tubular reactor connected with a reactor A / B in parallel on a pipeline between a preheater and a gas removal tower. After the rotating speed of a compressor is adjusted, the circulating flow of outlet gas is controlled to be 420000-440000 Nm < 3 > / h, and meanwhile effective gas components entering the tubular reactor and the reactor A / B in the system are controlled to comprise 16%-22% of CO, 3%-6% of NO and 12%-14% of MN; s2, after feeding of the reactor A / B and the tubular reactor is completed, a flow adjusting valve at an inlet of the tubular reactor is immediately adjusted, the ratio of the flow of the inlet of the reactor A / B to the flow of the inlet of the tubular reactor is controlled to be 4.5-5.5: 1, and meanwhile the content of methyl nitrite in the system is controlled to be 14.5%-15.8%. The bottleneck problem of high safety production risk caused by low dimethyl oxalate synthesis yield and high methyl nitrite content in the original system is solved.

The invention discloses a copper-silicon catalyst for plasma treatment as well as a preparation method and application of the copper-silicon catalyst. According to the method, a copper-silicon catalyst precursor prepared by a traditional ammonia distillation method is subjected to dielectric barrier discharge plasma treatment in the atmosphere of H2 / Ar and the like, and traditional high-temperature roasting and reduction processes are replaced. According to the method, efficient reduction and high dispersion of copper can be achieved at the room temperature, the Cu < + > / Cu0 proportion is regulated and controlled, and the strong interaction between metal and a carrier is enhanced. The catalyst is used in a reaction for preparing ethylene glycol through hydrogenation of dimethyl oxalate, the activity, selectivity and stability of the catalyst are higher than those of a traditional heat treatment catalyst, the dimethyl oxalate conversion rate reaches up to 100%, the ethylene glycol selectivity is larger than 97%, and the stability reaches 1000 h or above. The method is simple in process, low in energy consumption and environment-friendly, and has a wide industrial application prospect.

The invention discloses a preparation method of lithium difluoro (oxalato) borate. Lithium hydroxide, trimethyl borate, dimethyl oxalate and anhydrous ammonium bifluoride steam are used as raw materials to react in an ionic liquid medium. The method adopts a plasma activation technology, can be efficiently carried out in a low-temperature environment without traditional heating, not only shortens the reaction period, but also can inhibit fluorine source decomposition, oxalate hydrolysis and other side reactions, improves the selectivity of a target product, and uses the ionic liquid as a reaction medium, and the high polarity and low volatility of the ionic liquid can ensure the uniform dispersion of raw materials. Meanwhile, supercritical carbon dioxide extraction replaces traditional recrystallization, one-step purification is achieved by means of the selective dissolution characteristic of supercritical carbon dioxide extraction, the process steps are simplified, and solvent residues are reduced.

The invention discloses a preparation method and application of a nitrogen-anchored alkali metal monatomic supported catalyst. The catalyst is composed of an active component, a metal oxide auxiliary agent and a nitrogen modified carrier, and according to the preparation method, metal single atoms are anchored through the nitrogen modified carrier, and stable loading of high-dispersity active sites is achieved in combination with optimized roasting conditions (400-900 DEG C). The catalyst has excellent performance in synthesis of dimethyl carbonate (DMC) by decarbonylation of dimethyl oxalate: taking Cs (3%)-Ce (2%) / activated carbon as an example, the conversion rate of dimethyl oxalate reaches 82.05% and the selectivity of DMC reaches 86.91% under the conditions that the temperature is 220 DEG C, the dosage of the catalyst is 0.5 g and the reaction is performed for 2 h. A nitrogen anchoring strategy effectively inhibits metal agglomeration, a carrier microporous structure promotes mass transfer, and the specific surface area (704.38 m / g) and catalytic performance are kept stable after recovery. The catalyst has the advantages of high activity, high selectivity, low cost and easiness in industrialization, and an efficient catalyst solution is provided for synthesizing dimethyl carbonate by decarbonylation of dimethyl oxalate.

This invention proposes a heterogeneous catalyst and its application in the decarbonylation of alkyl oxalate to alkyl carbonate. The heterogeneous catalyst is a transition metal-modified organic amine-grafted polystyrene resin obtained by grafting chloromethylated polystyrene resin with an organic tertiary amine, followed by modification with a transition metal anion complex. This invention utilizes the heterogeneous catalyst to fully utilize dimethyl oxalate, an important intermediate in the coal-to-ethylene glycol process. By decarbonylating dimethyl oxalate, it can be efficiently converted to dimethyl carbonate and its derived alkyl esters under mild conditions.

This invention relates to the field of catalyst preparation technology, specifically to a copper-based catalyst for the hydrogenation of dimethyl oxalate and its preparation method. The catalyst is a Cu / SiO2 catalyst with a copper content of 5-25 wt% as the active component. It is prepared from raw materials such as a silicon source, a copper source, a hydroxyl protectant, and a hydrothermal promoter via a low-pressure ammonia stripping method. During the preparation process, by protecting the silanol hydroxyl groups and optimizing the ammonia stripping and complexation conditions, copper is highly dispersed and stable on the silicon support surface, effectively avoiding copper particle sintering and desilication problems. This catalyst exhibits excellent performance in the hydrogenation of dimethyl oxalate to ethylene glycol. Under reaction conditions of 170℃ and 2.8 MPa, the dimethyl oxalate conversion rate is ≥99%, the ethylene glycol selectivity is ≥97%, and the continuous operating time is ≥3000 h. It can significantly inhibit the formation of byproducts and carbon deposition, extend service life, and simultaneously reduce separation and purification energy consumption and catalyst replacement frequency. The raw materials used are conventional and controllable, and the preparation process is suitable for industrial production, showing broad application prospects.

The invention belongs to the field of catalysts, and particularly relates to a catalyst which comprises a carrier, an active component and an auxiliary agent, the active component and the auxiliary agent are loaded on the carrier, the active component is selected from one or more of copper, copper oxide and copper salt, and the auxiliary agent is fullerene. The carrier is selected from one or more of oxides of magnesium, boron, silicon, scandium, gallium, yttrium, zirconium, zinc, indium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium and ytterbium elements; the dispersity of the active component in the catalyst is 20%-100%. The invention also relates to a method for preparing the catalyst and a method for preparing methyl glycolate. The catalyst disclosed by the invention is high in active component dispersity, large in BET specific surface area, large in average pore size, high in mechanical strength, good in stability and long in service life; the catalyst can catalyze the hydrogenation reaction of dimethyl oxalate under low pressure, the raw material conversion rate is high, and the selectivity of methyl glycolate is high.

The invention provides a system and a method for preparing oxalic acid by hydrolyzing dimethyl oxalate. The system comprises a pre-reaction kettle, a methanol tower, a hydrolysis tower, a methanol tower condenser, a mother liquor heat exchanger and a crystallization unit which are connected with one another through pipelines. The method comprises the following steps: feeding a mixed solution of fresh dimethyl oxalate and desalted water and a thermally coupled circulating mother solution into a pre-reaction kettle for primary hydrolysis reaction, then feeding into a methanol tower for reactive distillation, returning a tower bottom solution to a hydrolysis tower material for reactive distillation, and returning a gas phase at the top of the hydrolysis tower to the bottom of the methanol tower material for feeding, refined methanol is extracted from the top of the methanol tower, one stream of oxalic acid hydrolysate in the kettle of the hydrolysis tower is mixed with the mother liquor and enters the pre-reaction kettle, and the other stream of oxalic acid hydrolysate is thermally coupled with the mother liquor and then enters the crystallization unit to obtain refined oxalic acid. The dimethyl oxalate conversion rate is high, the methanol purity is high, the monomethyl oxalate content in the oxalic acid hydrolysate is low, oxalic acid crystallization and thermal coupling of the mother liquor and the hydrolysate are facilitated, and the overall energy consumption is reduced.