36 results about "Paraldehyde" patented technology

The invention discloses an application of an ionic liquid in extraction of trioxymethylene, in the process of generating trioxymethylene by acid-catalyzed condensation of a formaldehyde aqueous solution, the ionic liquid is added as an extraction agent to extract and separate the trioxymethylene generated by reaction, and the ionic liquid is methyl tributyl phosphonium bis (trifluoromethanesulfonyl) imide salt; when the ionic liquid is used for extracting trioxymethylene, a ternary azeotropic system of trioxymethylene, water and methylene glycol can be broken, the ionic liquid and trioxymethylene are subjected to nonpolar Van der Waals' force interaction so as to realize extraction, and methylene glycol and water are left in a water phase through hydrogen-bond interaction, so that high-purity trioxymethylene with the purity of more than or equal to 99.5 wt.% is obtained.

The invention discloses piperonyl butoxide and a preparation method thereof. The preparation method comprises the following steps: carrying out mixing reaction on dihydrosassafras oil, acetyl chloride and trioxymethylene in the presence of concentrated hydrochloric acid; after the reaction is finished, chloromethyl material reaction liquid is obtained; mixing and reacting the chloromethyl material reaction liquid with sodium hydroxide and diethylene glycol monobutyl ether to obtain a product containing piperonyl butoxide. According to the preparation method of piperonyl butoxide, the dihydrosassafras oil, acetyl chloride and trioxymethylene are subjected to chloromethylation reaction in the presence of a small amount of concentrated hydrochloric acid, so that the use of a large amount of concentrated hydrochloric acid in the traditional process is avoided, and the problem of waste acid generated in the chloromethylation reaction process is solved; and meanwhile, the content of piperonyl butoxide in the product can be increased, and the content of piperonyl butoxide is ensured to be greater than 98%.

The invention relates to the technical field of formaldehyde copolymer production, and discloses a trioxymethylene static crystallization separation method which comprises the following steps: S1, cooling crystallization: the crystallization temperature is 25-30 DEG C, and the crystallization time is 3-4 hours; s2, discharging mother liquor; s3, sweating, wherein the sweating temperature is 50-55 DEG C, and the sweating time is 2-2.5 h; and S4, melting to obtain a high-purity product. According to the invention, the characteristic that the solubility of trioxymethylene is reduced along with temperature reduction is utilized, and separation and purification are realized through temperature gradient regulation and control. The content of trioxymethylene in the prepared finished product reaches 94-96% and is higher than that in the prior art by 90-92%, the formaldehyde content is only 0.1-0.2%, and the impurity content is lower.

This disclosure relates to the field of chemical production technology, and in particular to a production apparatus and method for trioxymethylene. The trioxymethylene production apparatus includes: a reaction unit, a separation unit, a first formic acid absorption unit, and a product distillation unit. The outlet of the reaction unit is connected to the inlet of the separation unit; the gas phase outlet of the separation unit is connected to the inlet of the first formic acid absorption unit; the outlet of the first formic acid absorption unit is connected to the inlet of the product distillation unit; and the liquid phase outlet of the separation unit is connected to the inlet of the reaction unit. The reaction unit is used to convert formaldehyde into trioxymethylene under the action of a catalyst. The separation unit is used to separate the gas phase product from the reaction unit into a liquid stream containing recycled formaldehyde and a gas phase stream containing trioxymethylene. The trioxymethylene production apparatus and method provided by this disclosure are used to remove formic acid, a byproduct in the trioxymethylene production process, and reduce equipment corrosion.

The invention relates to a method for producing polyacetal. In a method for producing polyacetal using a cationic active catalyst, the cationic active catalyst is efficiently deactivated and washed, thereby producing polyacetal having excellent thermal stability. A method for producing a polyacetal, characterized by comprising: a polymerization step for polymerizing at least one cyclic ether and / or cyclic formal containing trioxymethylene in the presence of at least one cationic active catalyst; and a deactivating and washing step in which the crude polyacetal obtained in the polymerization step is brought into contact with a deactivating and washing solution obtained by dissolving or suspending a basic compound in an aliphatic hydrocarbon solvent, thereby deactivating and washing the cationic active catalyst in the same step.

The present application provides a kind of recovery method and device of dilute aldehyde, the recovery method of dilute aldehyde includes the following steps: adding neutralizing agent to dilute aldehyde raw material liquid, the pH value of dilute aldehyde raw material liquid is 6.2-6.8, then rectification recovery treatment is carried out, obtains trioxymethylene material and heavy component material;Dehydration treatment is carried out to heavy component material, obtains dilute formaldehyde material and waste water material;It can recover the dilute aldehyde generated in trioxymethylene production, improve the recovery efficiency of trioxymethylene and formaldehyde in dilute aldehyde, reduce production cost.

A method for producing a polyacetal copolymer, which comprises: a step for obtaining a crude polyacetal copolymer by copolymerizing trioxymethylene, which is a main monomer (a), and a compound that is copolymerizable with trioxymethylene, which is a co-monomer (b), using a protonic acid as a polymerization catalyst (c); a step in which a solution of the crude polyacetal copolymer and the basic compound (d) is introduced into a predetermined continuous mixing device and mixed to obtain a mixture; and a step in which the mixture is introduced into an extruder and melt-kneaded, the basic compound (d) being a carbonate, bicarbonate or the like of an alkali metal element or a group 2 element (excluding Be), and the solvent of the solution of the basic compound (d) being a solvent having active hydrogen.

The invention discloses a preparation method of a posaconazole key intermediate diol olefin compound, which comprises the following steps: dissolving a compound 1 in an organic solvent A, adding a mixed solution of an additive and an organic solvent B, alkali a and trioxymethylene, continuing to react, and treating to obtain a compound 2; dissolving the obtained compound 2 in an organic solvent C, adding a reducing agent, and performing heating reflux reaction to obtain a compound I; the synthesis route is as follows: the reaction process is simple, the raw materials are simple and easy to obtain, harsh reaction conditions are not needed, the route is simple and convenient, the reaction operation is simple, and the drug development potential is achieved.

The invention discloses a metaldehyde continuous synthesis process and a production unit, and belongs to the field of metaldehyde synthesis, the process comprises the following steps: S1, uniformly mixing paraldehyde and acetaldehyde as a reaction mother solution; s2, continuously dropwise adding acetaldehyde and a catalyst into the reaction mother liquor, controlling the reaction temperature to be below-5 DEG C, continuously discharging the synthesized metaldehyde crystals and reaction feed liquid, and carrying out solid-liquid separation; s3, carrying out heat exchange and cooling on one part of the reaction material liquid obtained by separation, refluxing to the step S2 as a reaction mother solution, and depolymerizing the other part of the reaction material liquid to obtain acetaldehyde as an acetaldehyde reactant continuously dropwise added in the step S2; and purifying the separated metaldehyde to obtain the product. And S4, the step S2 and the step S3 are cyclically carried out. According to the scheme, continuous synthesis of metaldehyde is realized, the composition and the temperature of a reaction system are controlled through arrangement of the reaction mother liquor and reflux of the reaction feed liquid, the production efficiency and the product yield are improved, meanwhile, the production energy consumption is reduced, the process is simple, and large-scale production is facilitated.

The application provides a spherical lignin-phenolic resin and a preparation method and application thereof in adsorbing N-containing organic dyes, and belongs to the technical field of adsorbing materials. The lignin-phenolic resin with regular spherical morphology is prepared by one-step condensation polymerization reaction through the reverse suspension polymerization method under acid catalysis, wherein lignin, hydroquinone and trioxane are used as raw materials. The lignin belongs to renewable resources, has the characteristics of low cost and environmental friendliness, can replace phenol as the main phenol source, and the replacement rate can reach 75%. The yield of the synthesized phenolic resin is as high as 60-80%. In addition, the monomer type can be selected to introduce rich phenolic hydroxyl groups, sulfonic acid groups and other oxygen-containing groups in the resin, the monomer ratio is controlled to change the crosslinking structure of the resin, the adsorption capacity of the resin for N-containing organic dyes is effectively improved, and efficient adsorption of rhodamine B and methylene blue can be realized.

The invention discloses a full-temperature-range liquid phase temperature swing adsorption process for deep dehydration and impurity removal of trioxymethylene, which mainly comprises the following steps: raw material flow, temperature swing adsorption purification, temperature swing adsorption desorption and rectification concentration. The method comprises the following steps: purifying trioxymethylene which is obtained or purchased in a trioxymethylene production process and has the purity of 99.9%, the water content of 500-1000ppm, the content of micromolecular impurity components such as formaldehyde / methanol of 100-300ppm and the content of macromolecular impurity components such as hemiacetal and paraformaldehyde of more than or equal to 50ppm until the purity of the trioxymethylene is more than or equal to 99.999%, the water content of the trioxymethylene is less than or equal to 20-50ppm, and the water content of the trioxymethylene is less than or equal to 20-50ppm; the content of micromolecular impurity components such as formaldehyde and methanol is smaller than or equal to 20-50 ppm, the content of macromolecular impurity components such as methylal and paraformaldehyde is smaller than 20-50 ppm, the problems that the purity of products obtained through existing methods such as special rectification and membrane separation does not reach the standard, and production energy consumption and cost are high are solved, the process is simple, import is replaced, and the method is suitable for industrial production. And the quality requirement of polymer-grade trioxymethylene required by polyformaldehyde production is met.

The utility model discloses a generation device of a formaldehyde bottled gas standard substance. The generation device comprises a sublimation device, a catalytic cracking device, a gas storage bottle and a gas carrying system, according to the utility model, the formaldehyde bottled gas standard substance is prepared by a static cracking method, solid powdery trioxymethylene is adopted as a raw material, and a new way of preparing the gas standard substance from solid to gas is realized by regulating parameters such as cracking temperature, reaction time and the like. The device is simple in overall structure composition, small in size, convenient to disassemble and assemble and flexible to use, and the prepared formaldehyde gas standard substance is stored by adopting a gas cylinder, is convenient to carry and transport and can be flexibly applied to field measurement outside a specific laboratory. In addition, passivation coatings are arranged in the formaldehyde gas storage bottle and the formaldehyde conveying pipeline, so that the formaldehyde gas is prevented from being easily adsorbed, reacted and the like in the pipeline in the preparation process and the storage process in the gas bottle, the stable storage of the gas standard substance in the formaldehyde bottle is realized, and the accurate quantity value of the gas standard substance is ensured.

The application discloses a system and an energy-saving process for producing trioxymethylene by means of a heat pump assisted reaction rectification coupled variable pressure rectification, and the process comprises the following steps: feeding a formaldehyde aqueous solution into a pre-rectification tower to enrich, feeding the dilute formaldehyde collected from the top of the tower into a heat pump unit C1 to increase the pressure and temperature, and then taking the dilute formaldehyde as a tower bottom heat source of a high-pressure rectification tower; feeding the concentrated formaldehyde collected from the bottom of the pre-rectification tower into a reaction rectification tower, and converting the concentrated formaldehyde into trioxymethylene under the catalysis of a catalyst; taking the azeotrope of formaldehyde, water and trioxymethylene from the top of the reaction rectification tower as a tower bottom heat source of the pre-rectification tower, feeding the azeotrope into a low-pressure rectification tower after heat exchange and condensation, taking the azeotrope vapor from the top of the low-pressure rectification tower as a heat source of the tower bottom of the reaction rectification tower after increasing the pressure and temperature by means of a heat pump unit C2, feeding the azeotrope into the high-pressure rectification tower after heat exchange and condensation, feeding the dilute formaldehyde collected from the bottom of the low-pressure rectification tower back to the pre-rectification tower to enrich, and collecting the trioxymethylene product from the bottom of the high-pressure rectification tower. The application can improve the single-pass conversion rate of trioxymethylene, simplify the operation, and reduce the operation cost and energy consumption.

The utility model discloses a system for producing polyformaldehyde, and belongs to the technical field of polymer production. According to the continuous flow synthesis device disclosed by the utility model, formaldehyde, trioxymethylene, dioxopenta (penta) ring and polyformaldehyde are prepared into a continuous flow synthesis device through a plurality of different synthesis units, materials in each stage can be conveyed to the next stage through simple operation in the production process, and meanwhile, unreacted or waste materials in a system can be recycled; and the recycled materials enter the previous stage to be continuously utilized, so that the waste of the materials is avoided, and the energy consumption during subsequent waste treatment is also saved.

The utility model discloses a trioxymethylene light component removal tower feeding alkali adding system, which belongs to the technical field of trioxymethylene production and comprises an intermediate storage tank, a static tank, a trioxymethylene light component removal tower body and an alkali tank. The device has the beneficial effects that the dosage of put alkali liquor is adjusted by arranging the alkali inlet adjusting valve, the dosage of desalted water is controlled by arranging the desalted water inlet adjusting valve according to the dosage of the put alkali liquor, and the dosage of the desalted water is controlled by arranging the check valve. By arranging the first pipeline and the second pipeline, a dilute alkali solution obtained by mixing alkali liquor and desalted water can smoothly enter the first pipeline to be mixed with materials conveniently, the materials are prevented from reversely entering the alkali inlet pipeline and the desalted water pipeline, and the materials and the dilute alkali solution can be fully mixed conveniently by arranging the mixer and the static tank; and the dilute alkali solution is fully reacted with acidic substances such as formic acid and formaldehyde carried by the material, and meanwhile, the depolymerization of trioxymethylene is further prevented, so that the purity of trioxymethylene fed into the light component removal tower is greatly improved, and the rectification quality is improved.

The invention discloses a preparation method of modified polyformaldehyde with conductive and wear-resistant functions. The preparation method is characterized by comprising the following steps: putting 2-4 parts by weight of carbon nanotubes into 100 parts by weight of an oxidizing agent formed by mixing concentrated HNO3 and concentrated H2SO4, and reacting to obtain a modified carbon nanomaterial; dissolving 2-5 parts by weight of a coupling agent into 100 parts by weight of absolute ethyl alcohol, and reacting to obtain a silane coupling agent solution; soaking 8-10 parts by weight of MoS2 powder in 1-3 parts by weight of a silane coupling agent solution for reaction to obtain modified MoS2; the preparation method comprises the following steps: adding 1-3 parts by weight of a modified carbon nanomaterial and 1-3 parts by weight of modified MoS2 into 100 parts by weight of trioxymethylene, then adding 4-8 parts by weight of a boron trifluoride diethyl etherate complex catalyst, carrying out a polymerization reaction, and carrying out underwater granulation to obtain the modified polyformaldehyde particles, which have the advantages of low friction coefficient, high wear resistance and high conductivity.

The present invention discloses a method for synthesizing 5-ethyl-2-pyridineethanol, belonging to the technical field of organic synthesis. The present invention provides a method for synthesizing 5-ethyl-2-pyridineethanol. The method uses a specially prepared solid acid catalyst as a catalyst, paraldehyde and ammonia as raw materials, and adjusts the amounts of the raw materials and catalyst, vaporization temperature, reaction temperature, and reaction pressure. The yield of 2-methyl-5-ethylpyridine is as high as 86.5%. The obtained 2-methyl-5-ethylpyridine is reacted with a 37% methanol aqueous solution by adjusting the reaction conditions. The total yield of the final product, 5-ethyl-2-pyridineethanol, is as high as 81.2%.

The application belongs to the field of catalytic synthesis of trioxane, and particularly relates to a catalytic synthesis process and device of trioxane. The process comprises the following steps: step one, a mixture of methylal and methanol is mixed with oxygen-containing gas as raw material, and reacts to generate formaldehyde under the action of a first catalyst; step two, formaldehyde is dissolved and absorbed by water to obtain concentrated formaldehyde; step three, the concentrated formaldehyde is subjected to catalytic synthesis reaction under the action of a second catalyst to generate trioxane. The device comprises, in sequence in the feeding direction, an oxidation reactor, a heat exchanger, a formaldehyde absorption tower, a fixed bed reactor and a catalytic distillation tower; compared with pure methanol or pure methylal, the raw material of the application is easier to obtain and has lower production cost; the application obtains higher formaldehyde concentration through improved catalyst, and does not need to prepare high-concentration formaldehyde again by negative pressure concentration, so that the single-pass utilization rate of formaldehyde is improved, and various technical problems in the prior art are properly optimized.

The invention relates to a preparation method of diphenylmethane series diamine and polyamine, which comprises the following steps: reacting formaldehyde and aniline in the presence of an acid catalyst to prepare diphenylmethane series diamine and polyamine, sequentially neutralizing and washing the polyamine, and removing excessive aniline by adopting a vacuum distillation mode to prepare a qualified product. The trioxymethylene in the recycled aniline is removed by treating the recycled aniline, so that polycyclic high-polymer blockages, N-heterocyclic polyamine and N-methylaniline impurities in the reaction process can be greatly reduced, and the operation stability and the quality of an MDI product are improved.

The invention relates to the technical field of trioxymethylene production, and discloses a composition for trioxymethylene and a method for synthesizing trioxymethylene. The composition contains a formaldehyde aqueous solution, an acid catalyst and a catalytic promoter, in the formaldehyde aqueous solution, the content of formaldehyde is 28-75wt%, the content of methanol is 0.5-3wt%, and the content of formic acid is 0.02-0.5 wt%; the acid catalyst is sulfuric acid of which the concentration is not lower than 90wt%; relative to 1kg of the formaldehyde aqueous solution, the content of the acid catalyst is 0.3 to 1.0 mol, and the content of the catalytic promoter is 0.3 to 2.0 mol. According to the scheme, the activity of water in the formaldehyde aqueous solution can be reduced, and the relative volatility of the product trioxymethylene and water can be improved, so that the generation of a byproduct formic acid is reduced, and the conversion rate of formaldehyde and the yield of trioxymethylene are improved.

This application belongs to the field of membrane material technology, and more specifically, relates to a polyether-based random copolymer, its preparation method, and its carbon capture application. This application uses two or three of the monomers selected from trioxymethylene, 1,3-dioxolane, and 4-methyl-1,3-dioxolane, and trifluoromethanesulfonic acid as a catalyst, to undergo cationic ring-opening polymerization for random copolymerization in an anhydrous and oxygen-free environment, generating a polyether-based random copolymer. In gas separation membrane applications, this random copolymer breaks the current trade-off between permeability and selectivity in polymer membrane materials, exceeding the generally accepted Robeson upper limit for gas separation. Using the polyether-based random copolymer of this invention as a selective layer, the resulting thin-layer composite membrane exhibits significant advantages such as high gas flux, excellent mixed gas separation performance, and industrial scale-up capability, achieving the performance of current mainstream international CO2 separation membranes.

The invention relates to a trioxymethylene synthesis method, which comprises: S1, adding a formaldehyde aqueous solution, a solvent and a composite catalyst into a reaction kettle, and uniformly stirring and mixing to obtain a mixed solution; s2, heating the mixed solution obtained in the step S1 to 110-150 DEG C, and reacting for 1-4 hours to obtain a reaction solution; s3, cooling the reaction liquid obtained in the step S2 to 70-80 DEG C, standing for layering, separating out a water phase and a catalyst, and then washing the organic phase twice; and S4, feeding the washed organic phase obtained in the step 3 into a rectifying tower for rectification to obtain the product trioxymethylene, and recycling the solvent. The synthesis method disclosed by the invention is high in conversion rate and high in yield, and the purity of the obtained product is greater than 99.9%.

The invention discloses a trioxymethylene synthesis and concentration method, which comprises the following steps: feeding a concentrated formaldehyde solution into a trioxymethylene reactor, and enabling a sulfuric acid catalyst to automatically flow into the trioxymethylene reactor in a head tank through a mass flowmeter and a regulating valve; the concentrated formaldehyde solution is subjected to an exothermic reaction under the action of a sulfuric acid catalyst, a trioxymethylene gas-phase crude product is obtained at the top of the trioxymethylene reactor, the trioxymethylene gas-phase crude product is sent to a trioxymethylene concentration tower to be continuously concentrated, and concentrated trioxymethylene is obtained at the top of the trioxymethylene concentration tower; the mass concentration of the concentrated formaldehyde solution is 55-75%, and the mass concentration of the sulfuric acid catalyst in the trioxymethylene reactor is 0.4-2%. According to the invention, the corrosion of the reaction system is reduced, the coking blockage of the reboiler is reduced, the energy consumption is reduced, and the reaction conversion rate is improved.

The synthesis method comprises the following steps: by taking nitroethane, formaldehyde and liquid bromine as reaction raw materials, continuously synthesizing 2-bromo-2-nitropropanol (BNPOH) in an alkaline aqueous solution in two steps under an ice bath condition; the method comprises the following steps: by taking concentrated sulfuric acid as a catalyst, carrying out condensation on BNPOH and trioxymethylene to synthesize bis (2-bromo-2-nitropropanol) formal (BBNPF); then sodium azide is used as an azidation reagent, and heating and stirring reaction are carried out in the mixed system; and after the reaction is finished, extracting with dichloromethane, washing with water, distilling and concentrating to obtain a light yellow liquid product, and carrying out column chromatography separation to obtain a high-purity product bis (2, 2-diazido propyl alcohol) formal (BDAPF). The product disclosed by the invention is a novel gem-diazido acetal energetic molecule, has proper density and viscosity and lower glass transition temperature compared with an A3 plasticizer molecule, can be used as an A3 plasticizer substitute for a solid propellant, and has a better application prospect.

The invention discloses a technological synthesis method of 6-(N-ethyl-4-toluidine)-2-methylfluorane, and relates to the technical field of organic synthesis. The method comprises the following four steps of: (1) reacting resorcinol as shown in a formula I and p-toluidine as shown in a formula II in an acid catalysis system and an organic solvent at 110-145 DEG C for 20-28 hours to obtain a formula III; (2) carrying out reductive amination on the compound shown in the formula III and a compound shown in the formula IV (paraldehyde) in the presence of a catalyst under the hydrogen pressure of 0.1-5 MPa to obtain a compound shown in the formula V; (3) reacting the formula V with a formula VI (phthalic anhydride) in an organic solvent at 100-120 DEG C for 10-15 hours to obtain a formula VIII; and (4) carrying out dehydration condensation on the formula VIII and the formula IX (p-cresol) under an acidic condition to obtain a target product. Raw materials are easy to obtain, the yield of each step is larger than or equal to 80%, energy consumption and cost are reduced, operation safety is improved, the method is suitable for industrial production, and import dependence of high-end heat-sensitive materials can be broken through.

A method for producing a polyacetal copolymer, which includes a step of copolymerizing 100 parts by mass of trioxane (A), 0.05 to 5 parts by mass of a cyclic acetal compound having an oxoalkylene group having 2 or more carbon numbers in a ring (B), and 0.001 to 0.5 parts by mass of a prescribed fatty glycidyl ether compound (C) having a sodium content of 0.1 to 100 parts by mass ppm in the presence of a linear acetal compound (D) as a molecular weight regulator, wherein in the step, the total mass (g) of (A) to (C) is defined as a, the number of moles of (D) is defined as b, and the total number of moles of moisture and methanol contained in (A) to (C) is defined as c and d, respectively, and is set to satisfy (b + c + d) / a = 4.5 to 9 μmol / g.

The invention relates to the technical field of lithium metal battery electrolytes, in particular to an electrolyte, application thereof and a cathode-free lithium metal battery. The invention provides an electrolyte. The electrolyte comprises a lithium salt, a solvent, a diluent and an additive, the diluent comprises a 1, 3-dioxane derivative, acetal carbon located at the position 2 in the 1, 3-dioxane of the 1, 3-dioxane derivative is substituted by Rf1 and Rf2, and the Rf1 and the Rf2 are the same or different; the Rf1 and the Rf2 are independently fluorine substituted alkyl groups; the additive is prepared from one or more of 1, 3, 5-trioxane, a derivative of the 1, 3, 5-trioxane and paraldehyde, and the additive is prepared from one or more of 1, 3, 5-trioxane, a derivative of the 1, 3, 5-trioxane and paraldehyde. The electrolyte can give consideration to both excellent ion transmission and lithium deposition dynamic performance under a low-temperature condition.

The invention discloses a full-temperature-range gas phase pressure swing adsorption process crossing trioxymethylene-formaldehyde-water ternary azeotropic composition, which mainly comprises the steps of raw material flow, pressure swing adsorption concentration, pressure swing adsorption desorption and dilute aldehyde recovery side flow circulation, and utilizes cyclic operation of pressure swing adsorption and desorption. According to the method, the existing technology, including extractive distillation, which is adopted in the production process of trioxymethylene and is composed of trioxymethylene-formaldehyde-water ternary azeotrope is effectively matched and replaced, other processes do not need to be changed, and the energy consumption and the production cost are greatly reduced.

The application provides a method and device for producing polymethoxy dimethyl ether from polyformaldehyde production waste, and belongs to the technical field of polyformaldehyde. The production process of polyformaldehyde comprises a formaldehyde production step, a trioxymethylene production step and a polyformaldehyde production step; the method for producing polymethoxy dimethyl ether from polyformaldehyde production waste comprises: condensation reaction of formaldehyde-containing waste liquid generated in the formaldehyde production step, the trioxymethylene production step and the polyformaldehyde production step with methanol to generate methylal; condensation reaction of the heavy boiler produced in the trioxymethylene production step with the methylal to obtain polymethoxy dimethyl ether. The method and device for producing polymethoxy dimethyl ether from polyformaldehyde production waste can fully utilize the formaldehyde-containing waste liquid and the trioxymethylene heavy boiler in the polyformaldehyde production process, reduce the loss of production equipment, and ensure the product quality of polyformaldehyde.

The present application relates to the technical field of preparing formic acid gas standard substance, and more particularly to a system and method for preparing formic acid gas standard substance in air. The system comprises a nitrogen source, an oxygen source, a vacuum pump, a raw material container, an intermediate container, a finished product container, a first three-way valve, a second three-way valve, a catalytic cracking pipe and a catalytic oxidation pipe; the nitrogen source, the oxygen source and the vacuum pump are communicated with the first three-way valve; the raw material container is communicated with the intermediate container through the second three-way valve and the catalytic cracking pipe in sequence; the intermediate container is communicated with the finished product container through the catalytic oxidation pipe; and the first three-way valve is communicated with the second three-way valve. The present application prepares formic acid standard gas through a two-step reaction with trioxane as a raw material, avoids the quality loss in the process of preparing formic acid standard gas with fuming formic acid, and can accurately obtain the amount of formic acid standard gas.