88 results about "Oleum" patented technology

The invention discloses a preparation device and a preparation method of electronic-grade sulfuric acid. The device mainly comprises a sulfuric acid storage tank, a wiped-film evaporator, a liquid storage tank, a sulfur trioxide absorption tank, a packing absorption tower, a heat exchanger, a filter and the like. A fuming sulfuric acid storage tank is conveyed to a wiped-film evaporator through a diaphragm pump to evaporate sulfur trioxide, the evaporated sulfur trioxide is subjected to circular absorption reaction to generate sulfuric acid, and electronic-grade sulfuric acid is obtained after filtration. The method is simple in technological process, low in evaporation process temperature, high in efficiency and low in metal residue, and high-quality electronic-grade sulfuric acid is obtained.

The invention relates to the technical field of fine chemical engineering, and provides a method for synthesizing O-methyl-N-nitroisourea by a micro-channel reactor, which comprises the following specific steps: adding nitric acid into a four-neck bottle for cooling, dropwise adding fuming sulfuric acid, controlling the temperature of a mixed solution, adding sulfuric acid into the four-neck bottle, and reacting for 2-4 hours; stirring and a low-temperature constant-temperature reaction bath are started to cool sulfuric acid, disulfate is put into a four-opening bottle to prepare a disulfate sulfuric acid solution, a mixed acid metering pump is started, a disulfate sulfuric acid solution metering pump is started, the disulfate sulfuric acid solution is mixed and enters a nitration micro-channel reaction device, and after heat preservation of nitration liquid is completed, the nitration liquid is dropwise added till the temperature is lowered to 0 DEG C in advance; the preparation method comprises the following steps: adding water into a reaction kettle, dropwise adding while stirring, continuously cooling and preserving heat after dropwise adding, carrying out suction filtration on eluted feed liquid, and washing a filter cake with chilled water to obtain an O-methyl-N-nitroisourea wet product, so that the defects of long production period, low effective productivity, lower safety coefficient and relatively higher safety risk of a traditional method for synthesizing O-methyl-N-nitroisourea are overcome.

Methods and associated production plants are disclosed for producing concentrated oleum or sulfur trioxide therefrom with high purity, and particularly with minimal sulfur dioxide. The methods involve use of a single contact, single absorption sulfuric acid plant operating under an unconventional set of parameters including: reacting sulfur and high purity oxygen in a combustion reactor to form sulfur dioxide at a concentration between 11.5 and 20% by volume and with an atypical oxygen to sulfur dioxide molar ratio ≥ 1; atypically catalytically converting > 96% by volume of the sulfur dioxide to sulfur trioxide in a contact apparatus; and atypically recycling > 95% by volume of the total gases from an absorption apparatus to the combustion reactor. Concentrated oleum with < 300 ppm dissolved sulfur dioxide can desirably be produced with sulfur utilization ≥ 80% using a smaller, cost-effective sulfuric acid plant. The co-production of unnecessary sulfuric acid can also be reduced.

The invention provides a continuous production method of 2-acrylamido-2-methylpropanesulfonic acid and application of the 2-acrylamido-2-methylpropanesulfonic acid. The continuous production method comprises the following steps: S1, adding part of acrylonitrile into a reaction kettle in advance; s2, continuously adding the residual acrylonitrile into the mixing kettle, adding a pre-prepared fuming sulfuric acid solution, mixing, and controlling the mixing temperature at-10-10 DEG C to obtain a first mixed solution; s3, continuously adding the first mixed solution obtained in the step S2 into a supergravity reactor, gasifying isobutene at a constant speed, and introducing the gasified isobutene into the supergravity reactor for reaction to obtain a second mixed solution containing 2-acrylamido-2-methylpropanesulfonic acid; and S4, adding a second mixed solution containing 2-acrylamido-2-methylpropanesulfonic acid into the reaction kettle, continuously reacting, and after the reaction is finished, filtering and drying to obtain the 2-acrylamido-2-methylpropanesulfonic acid. The 2-acrylamido-2-methylpropanesulfonic acid prepared by adopting the production method is high in purity and high in product synthesis efficiency, and meanwhile, rectifying still residues generated in the reaction process are relatively low.

The invention belongs to the field of inorganic chemical industry, and particularly relates to a method and a system for efficiently utilizing a phosphate fertilizer byproduct, the method comprises the following steps: carrying out acidolysis on fluosilicic acid with the concentration of more than or equal to 45% wt and concentrated sulfuric acid to generate a mixed solution of silicon tetrafluoride gas and fluorosulfonic acid; the mass ratio of the fluosilicic acid to the concentrated sulfuric acid is controlled to be 1: (4-15); pyrolyzing the obtained fluorosulfonic acid to generate dilute sulphuric acid, hydrogen fluoride and water vapor, forming 98% concentrated sulphuric acid from part of dilute sulphuric acid and fuming sulphuric acid, drying hydrogen fluoride to obtain crude hydrogen fluoride gas, and condensing and rectifying to obtain anhydrous hydrogen fluoride; the rest dilute sulphuric acid is partially compounded and then returned for acidolysis, and the rest dilute sulphuric acid is used for producing white carbon black and flows back to a wet-process phosphoric acid system; and circularly absorbing the obtained silicon tetrafluoride gas by using secondary concentrated fluosilicic acid to obtain fluosilicic acid with the mass concentration of more than or equal to 45%, recycling the fluosilicic acid for acidolysis reaction, and modifying the concentrated by-product silicon dioxide to obtain the high-activity white carbon black. The problems of energy consumption and cost are solved, and efficient circulation and poly-generation of fluorine and silicon resources are achieved in the whole process.

The invention relates to the field of preparation of chemical products, and discloses a preparation method of electronic-grade sulfuric acid and a device for preparing the electronic-grade sulfuric acid. The preparation method comprises the following steps: S1, carrying out reaction and twice conversion and twice absorption on liquid sulfur and air to obtain fuming sulfuric acid and first tail gas; s2, evaporating the fuming sulfuric acid to obtain SO3-containing gas and evaporated fuming sulfuric acid, purifying the SO3-containing gas, performing third absorption on the obtained purified SO3-containing gas by using ultrapure water, and performing SO2 removal and filtration on the obtained high-purity sulfuric acid to obtain electronic-grade sulfuric acid; and S3, returning the evaporated fuming sulfuric acid to the step S1, and carrying out two-time conversion and two-time absorption. According to the invention, fuming sulfuric acid and electronic-grade sulfuric acid production systems are combined, recycling of three wastes is realized, and the method is suitable for large-scale industrial production of electronic-grade sulfuric acid.

The invention relates to a method for removing cyclohexane in a low-molecular brominated polystyrene recovery solvent, which comprises the following steps: adding the recovery solvent containing cyclohexane and dichloromethane into a reaction bottle, and then adding a certain amount of fuming sulfuric acid; stirring and reacting for a period of time at a certain reaction temperature; adding water for quenching, standing for layering, washing an organic layer to be neutral, and standing for layering; and rectifying the organic layer, and collecting corresponding fractions. The used fuming sulfuric acid contains excessive sulfur trioxide, the sulfonation capacity is higher, cyclohexane is sulfonated to generate sulfonic acid group cyclohexane, then the sulfonic acid group cyclohexane is removed through water washing, the removal rate is high, the operation is convenient and fast, the cost is low, and the method is suitable for industrial production.

The invention discloses a method for producing SO3, which comprises the following steps: carrying out combustion reaction on sulfur and first oxygen-containing gas, and outputting SO2-containing first mixed gas; the first mixed gas and second oxygen-containing gas are subjected to a catalytic oxidation reaction, and second mixed gas containing SO3 is obtained; carrying out first fuming sulfuric acid absorption treatment on the second mixed gas to obtain third mixed gas and second fuming sulfuric acid; circulating and returning the third mixed gas to be mixed with the sulfur and the first oxygen-containing gas; performing separation treatment on the second fuming sulfuric acid to obtain third fuming sulfuric acid and SO3 gas; and mixing the third fuming sulfuric acid with the first fuming sulfuric acid, and carrying out absorption treatment on the second mixed gas. The method can meet the practical requirements that the SO3 product is produced, but sulfuric acid is not produced or sulfuric acid is produced as little as possible.

An integrated process for co-production of phosphorus pentafluoride (PF5) and fluorosulfonic acid (HSO3F) in high yield and purity through a single reaction step is provided. The method comprises reacting a first reagent comprising an aqueous solution of hexafluorophosphoric acid (HPF6) and hydrofluoric acid (HF) with a second reagent comprising fuming sulfuric acid (H2SO4SO3), and recovering a product mixture comprising phosphorus pentafluoride (PF5) and fluorosulfonic acid (HSO3F).

The invention provides a preparation method of high-purity isosulfur blue, which comprises the following steps: by taking 2-chlorobenzaldehyde as a raw material, after sulfonation reaction of fuming sulfuric acid, adding calcium carbonate to convert excessive sulfuric acid into calcium sulfate precipitate, and filtering to remove the calcium sulfate precipitate, thereby reducing inorganic salt residues in an intermediate I; carrying out substitution reaction on the intermediate I under the action of sodium sulfite and sodium hydrogen sulfite, adding a calcium chloride solution after the reaction to enable sulfite to form calcium sulfite precipitate, and carrying out filtration, vacuum concentration and methanol pulping to obtain a high-purity intermediate II; the intermediate II reacts with N, N-diethylaniline to generate an intermediate III, then the intermediate III is oxidized by silver oxide to generate an isosulfur blue silver salt, sodium carbonate is added to directly convert the silver salt into a sodium salt form, and a high-purity isosulfur blue finished product is obtained through ethyl acetate crystallization. According to the method, inorganic salt residues are remarkably reduced, the product purity and yield are improved, meanwhile, the technological process is simplified, the solvent usage amount is reduced, operation is safe and environmentally friendly, and industrial production is facilitated.

The application discloses a multi-stage fuming sulfuric acid absorption tower and a process method for absorbing sulfur trioxide by using the fuming sulfuric acid absorption tower. The multi-stage fuming sulfuric acid absorption tower comprises a primary absorption assembly and a secondary absorption assembly. The primary absorption assembly is provided with a first containing cavity. A first acid distributor is arranged in the first containing cavity and is arranged close to the upper wall surface of the first containing cavity and used for spraying acid liquid into the first containing cavity. The primary absorption assembly is provided with a flue gas inlet communicated with the first containing cavity. The secondary absorption assembly is arranged above the primary absorption assembly. The secondary absorption assembly is provided with a second containing cavity. The second containing cavity is communicated with the first containing cavity and used for receiving flue gas from the first containing cavity. A second acid distributor is arranged close to the upper wall surface of the second containing cavity and used for spraying acid liquid into the second containing cavity. The upper end of the secondary absorption assembly is provided with a flue gas outlet communicated with the second containing cavity. In this way, the sulfur trioxide absorption rate can be improved, and the product purity can be ensured.

This invention relates to the field of flame retardant chemical synthesis technology, and discloses ethylene bis(tetrabromophthalimide) and its preparation method and applications. The method includes reacting phthalic anhydride and ethylenediamine in an aqueous medium at a controlled mass ratio of 3.0-5.5:1 to obtain an intermediate; reacting the intermediate with bromine in a fuming sulfuric acid medium, controlling the dropping temperature at 45-60℃ and the holding temperature at 130-150℃; and washing the reaction product followed by high-temperature heat treatment at 150-220℃ to constant weight. This invention effectively inhibits residual active amino groups and organic carbonization by strictly controlling the intermediate synthesis ratio and the temperature range of the bromination reaction. By utilizing high-temperature heat treatment, it thoroughly removes deep-seated acidic volatiles that cannot be removed by conventional drying, solving the problems of yellowing appearance, poor heat resistance, and easy corrosion of processing equipment in existing products. It is applicable to the field of flame-retardant engineering plastics.

The invention discloses a device and a method for preparing electronic-grade sulfuric acid from ultra-pure fuming sulfuric acid. The device comprises an ultra-pure fuming sulfuric acid system, a sulfur trioxide evaporation system and an ultra-pure sulfur trioxide absorption system. By adopting the device and the method disclosed by the invention, high-quality sulfuric acid can be produced, the content of single metal ion impurities is less than or equal to 0.1 ppb, and 0.2-micron particles are controlled by filtering through a 0.05-aperture filter.

The invention provides a cyclohexanone-oxime transposition process flow and a cyclohexanone-oxime transposition device for partitioned sulfuric acid concentration supply, which are used for partitioned supply and accurate control of sulfuric acid concentration in different stages of transposition reaction, in the transposition process flow, fuming sulfuric acid is proportionally distributed to a high-concentration acid channel and a low-concentration acid channel through an intelligent metering and acid adding module, and the high-concentration acid channel and the low-concentration acid channel are communicated with the high-concentration acid channel and the low-concentration acid channel; the high-concentration acid channel is used for a one-step transposition reactor of a one-step reaction zone of the two-step transposition process, the low-concentration acid channel is used for a two-step transposition reactor of a two-step reaction zone of the two-step transposition process, and in the transposition process flow, a multi-mode fuzzy self-adaptive prediction PID control algorithm is adopted, control modes are switched according to reaction stages, and the multi-mode fuzzy self-adaptive prediction PID control algorithm is adopted. The first-step reaction zone adopts high-precision temperature-acid concentration cascade control, and the second-step reaction zone adopts by-product prediction feedforward control; according to the invention, partitioned supply and accurate control of sulfuric acid concentration in the first-step reaction zone and the second-step reaction zone can be realized, the reaction efficiency and selectivity are improved, and acid consumption and by-product generation are reduced.

The present application belongs to the field of boron trifluoride production, and relates to a method for preparing boron trifluoride and its complex by continuous flow reaction. The method comprises the following steps: uniformly mixing boric acid with concentrated sulfuric acid, then adding oleum or continuously introducing sulfur trioxide gas to obtain an oleum solution of boric acid; introducing the obtained solution and anhydrous hydrogen fluoride gas into a continuous flow reactor at a uniform speed to obtain boron trifluoride gas; purifying and removing impurities from the boron trifluoride gas generated in the reaction; continuously introducing the purified boron trifluoride gas into a complexing solvent for a complexing reaction to obtain a boron trifluoride complex. The method uses a continuous flow reactor to react anhydrous hydrogen fluoride with the oleum solution of boric acid, so that the raw materials can be continuously and uniformly mixed, the reaction is rapid and complete, the process conditions are simplified, the sulfuric acid waste liquid can be recycled after treatment, and the method has economic advantages and process innovation, and is suitable for industrial production.

This invention proposes an environmentally friendly and efficient method for preparing aminosulfonic acid, belonging to the field of chemical technology. It includes: (1) sulfonation reaction; (2) crude product filtration; (3) dissolution and crystallization; and (4) drying and packaging. The reaction process of this invention features mild reaction conditions, short reaction time, and a yield exceeding 97%. The process, using fuming sulfuric acid and urea at a lower temperature, significantly reduces polluting components in the waste gas. It has many advantages, including simple operation, low cost, high yield, and greater environmental friendliness.

An integrated process for co-producing phosphorus pentafluoride (PFs) and fluorosulfonic acid (HSOsF) in high yield and purity via a single reaction step is provided. The method includes reacting a first reagent comprising an aqueous solution of hexafluorophosphoric acid (HPFG) and hydrofluoric acid (HF) with a second reagent comprising fuming sulfuric acid (H2SO4*SO3) and recovering a product mixture comprising phosphorus pentafluoride (PFs) and fluorosulfonic acid (HSO3F).

The utility model relates to the technical field of sulfur trioxide separation and evaporation, and discloses a sulfur trioxide production device, which aims to solve the problem in sulfur trioxide evaporation in the prior art, and comprises a fuming sulfuric acid storage tank, the fuming sulfuric acid storage tank is connected with a film evaporator, and the film evaporator is connected with a saturated steam or heat-conducting oil pipeline and a fuming acid pipeline. The top of the film evaporator is connected with a gaseous sulfur trioxide pipeline, the gaseous sulfur trioxide pipeline is connected with a condenser, the condenser is connected with a liquid sulfur trioxide tank, a swirler is arranged in the film evaporator and comprises a first-stage swirling vane arranged at the lower part in the film evaporator, and a second-stage swirling vane is arranged at the upper part in the film evaporator; the film evaporator is utilized to separate gas-phase sulfur trioxide from low-concentration fuming acid, so that the sulfur trioxide is evaporated quickly, the swirlers are arranged in the film evaporator, materials are prevented from being carried by gas, and the swirlers are arranged in an upper stage and a lower stage, so that the evaporation rate of the sulfur trioxide can be effectively improved.

This invention discloses a method for producing chromatographic grade cyclohexane, comprising the following steps: A) Taking cyclohexane as raw material, adding fuming sulfuric acid to the cyclohexane raw material, stirring and allowing it to stand, and then separating the cyclohexane; B) Adding pure water to the cyclohexane obtained in step A, stirring and allowing it to stand, and then separating the cyclohexane; C) Adding activated alumina and 10X molecular sieve to the cyclohexane obtained in step B, stirring and allowing it to stand, and then filtering; D) Distilling the cyclohexane obtained in step C to obtain chromatographic grade cyclohexane. This invention uses fuming sulfuric acid to remove impurities from the cyclohexane raw material, then washes it directly with pure water, followed by adsorption filtration using molecular sieves and alumina, and finally distillation to obtain chromatographic grade cyclohexane with optical properties meeting market customer requirements. The preparation process of this invention is not complex, the consumption of auxiliary agents is low, and the cost is within a controllable range, achieving the goal of industrial production of chromatographic grade cyclohexane with high optical properties.

The invention provides a process and a plant for the production of ε-caprolactam and crystalline ammonium sulfate in an industrial-scale plant, wherein the plant comprises a Beckmann rearrangement reaction section, an ammonium sulfate crystallization section, and one or more heat exchangers configured to transfer heat from the Beckmann rearrangement reaction section to the ammonium sulfate crystallization section and wherein the process comprises the steps of:a) feeding(i) cyclohexanone oxime and(ii) oleum and / or sulfuric acidto the Beckmann rearrangement reaction sectionb) reacting components (i) and (ii) in the Beckmann rearrangement reaction section to form a reaction mixture comprising ε-caprolactam, whereby heat of reaction is generated;c) discharging the reaction mixture comprising ε-caprolactam from the Beckmann rearrangement reaction section;d) removing partially or fully the heat of reaction generated in the Beckmann rearrangement reaction section by one or more heat exchangers configured to transfer heat from the Beckmann rearrangement reaction section;e) feeding an aqueous liquid comprising ammonium sulfate to the ammonium sulfate crystallization section;f) introducing heat into the ammonium sulfate crystallization section comprising the aqueous ammonium-sulfate-comprising liquid by one or more heat exchangers configured to transfer heat into the ammonium sulfate crystallization section;g) forming ammonium sulfate crystals by evaporative crystallization in the ammonium sulfate crystallization section;characterized in thath) the heat of reaction removed from the Beckmann rearrangement reaction section in step d) is at least partially or fully transferred to the ammonium sulfate crystallization section in step f).

The invention discloses a method for preparing methylene methyldisulfonate through a one-pot method, and belongs to the technical field of electrolytes.The method is characterized by comprising the following steps that firstly, methanesulfonic acid is added into a three-neck bottle, then liquid sulfur trioxide or fuming sulfuric acid is added, and the temperature is increased to 130-170 DEG C; 2, preserving heat for 6-8 hours, cooling, and adding an inert solvent; 3, paraformaldehyde is added, and the temperature is raised to 40-90 DEG C; step 4, slowly dropwise adding a water binding agent, and after dropwise adding, keeping the temperature for 2-6 hours to carry out cyclization reaction; 5, after the reaction is finished, cooling to 40-90 DEG C, and standing to separate out an upper organic layer; step 6, cooling to 10-30 DEG C, and carrying out suction filtration; and step 7, drying under reduced pressure at 40 DEG C to obtain the methylene methyldisulfonate. The method has the effects of effectively solving the problem that a large amount of waste phosphoric acid is generated in the existing methylene methyldisulfonate preparation method technology, improving the productivity and reducing the cost.

The utility model discloses an efficient fuming sulfuric acid and washing acid mixing device which comprises an acid mixing tank filled with washing acid, the side end of the bottom of the acid mixing tank is fixedly connected with a pre-mixing assembly through a connecting guide pipe, a circulating pump is fixed on the connecting guide pipe, and the top of the pre-mixing assembly is fixedly connected with a fuming sulfuric acid input pipe. The bottom of the pre-mixing assembly is fixedly connected with the top of the acid mixing tank through a guide pipe, and the pre-mixing assembly can increase the mixing contact area of fuming sulfuric acid and washing acid, so that the contact area of the fuming sulfuric acid and the washing acid is increased through the baffling effect of the pre-mixing assembly, two acidic materials can be mixed more sufficiently, the mixing efficiency is improved, and the mixing effect is improved. And through the pre-mixing assembly, efficient mixing can be realized in a relatively small space, so that the occupied area of the whole device is reduced, and the device is more convenient to use.

The invention discloses a preparation device and method of a sulfonic acid monomer, and relates to the technical field of chemical engineering. The preparation method comprises the following steps: S1, pumping acrylonitrile and fuming sulphuric acid into a premixer for mixing; s2, the mixed liquid enters a heat exchanger to be heated, and the temperature is controlled to range from 15 DEG C to 20 DEG C; s3, the heated mixed liquid enters a first-stage dynamic tubular reactor, gasified isobutene is introduced from lower, middle and upper layers of gas inlet branch pipes at the same time, and the reaction temperature is 40-45 DEG C; s4, after the materials react in the first-stage dynamic tubular reactor for 3-7 min, the materials enter a second-stage dynamic tubular reactor, and the reaction temperature ranges from 45 DEG C to 50 DEG C; and S5, cooling, carrying out solid-liquid separation, and drying to obtain the product. By adopting the method disclosed by the invention, the continuous and stable preparation of the sulfonic acid monomer 2-acrylamido-2-methylpropanesulfonic acid can be realized, and compared with the traditional process, the reaction time is greatly shortened, and the product purity (without refining and washing) can reach 99% or above.

The invention relates to the production of methanol via the partial oxidation of methane using iodine(III) catalysts, which allow the reaction to be performed at low temperatures and pressures. Similar chemistry can be used to make methyl bisulfate from methane in the presence of oleum, and to make ethylene glycol via the partial oxidation of ethane.

The invention discloses a process for producing sulfamic acid by a solid-phase dilution method. The invention relates to a sulfamic acid production process by a solid phase dilution method. The process comprises the following steps: S1, preparing a pre-reaction material with the sulfuric acid concentration of 105.5%; s2, adding the pre-reaction material and urea into a pre-sulfonation reactor for reaction, enabling reaction liquid to overflow into the sulfonation reactor, and performing sulfonation reaction to obtain a liquid mixture; s3, carrying out immobilization on the liquid mixture through speed-adjustable centrifugal anti-spiral immobilization equipment, and feeding an obtained immobilization material into a dilution kettle; s4, adding mother liquor into the dilution kettle to dilute and adjust the viscosity of the material; and S5, performing solid-liquid separation on the liquid material with the adjusted viscosity to obtain a sulfamic acid crude product and dilute sulphuric acid, and performing crystallization purification on the sulfamic acid crude product to obtain sulfamic acid. The sulfamic acid production process is improved, excessive fuming sulphuric acid entering the dilution process in the reaction process is remarkably reduced, the generation of a new byproduct dilute sulphuric acid is reduced, and the production cost is reduced.

The invention relates to a method for the continuous production of gaseous boron trifluoride, the method comprising the steps of: a) providing a composition A comprising boron trifluoride (BF3) and optionally one or more additional volatile compounds F1; b) continuously adding, to a first reactor R1: - a sulphuric acid solution and a solution B comprising oleum and volatile additional compounds F2 to form a solution C; - composition A; to form: - a liquid phase L1 comprising oleum, sulphuric acid and BF3 and - a gaseous phase G1 comprising the volatile additional compounds F1 and F2; c) continuously removing the gas phase G1 comprising the additional volatile compounds F1 and F2, preferably by means of negative pressure; d) continuously adding the liquid phase L1 to a second reactor R2 and continuously adding, to the reactor R2, a composition D1 of water or an aqueous composition of boron trifluoride D2 or a composition D3 comprising hydrated boron trifluoride, referred to as boron trifluoride hydrates, wherein the compositions D1 and D2 do not contain any additional compound F1 to produce a gaseous phase E of boron trifluoride and a liquid phase L2.

The invention discloses a method for preparing sodium 3-diphenylphosphinobenzenesulfonate, which belongs to the field of organic synthesis technology. Using triphenylphosphine as raw material, fluoroboric acid is added to 1,4-dioxane to obtain triphenylphosphine fluoroborate, which is then reacted with fuming sulfuric acid for monosulfonation, and sodium hydroxide is used to form a sodium salt to obtain sodium 3-diphenylphosphinobenzenesulfonate. This process has relatively few disulfonation by-products and the yield is increased to 73-78%, ensuring product purity and providing guarantee for large-scale production.

The invention relates to a preparation method of 4, 5-diaminobenzene-1, 3 disulfonic acid, which comprises the following steps: a, adding concentrated sulfuric acid into a container provided with a thermometer and a stirring device, controlling the temperature and slowly adding o-phenylenediamine to obtain a sulfuric acid solution of o-phenylenediamine; b, slowly dropwise adding fuming sulfuric acid into the sulfuric acid solution of o-phenylenediamine in the step a, carrying out heat preservation reaction, and cooling; c, pouring the product in the step b into an ice-water mixture, adding activated carbon, stirring, and filtering to remove the activated carbon to obtain a diluent; d, carrying out reduced pressure distillation, concentration and cooling on the diluent; e, cooling, stirring, filtering and taking a solid to obtain a 4, 5-diaminobenzene-1, 3 disulfonic acid crude product; and f, adding the crude product into an organic solvent, pulping, washing acid, stirring, filtering to obtain a solid, and drying to obtain the 4, 5-diaminobenzene-1, 3-disulfonic acid. The method has the advantages of mild reaction conditions, normal pressure reaction, high yield, easily available raw materials and simple process, can be directly obtained by one-step sulfonation, and is suitable for industrial production.

The present invention provides a method for preparing phosphorus pentafluoride with high purity and low waste acid, comprising the following steps: (1) mixing hydrogen fluoride and polyphosphoric acid in an HPF6 synthesis kettle for reaction to obtain a mixed solution containing hexafluorophosphoric acid and water; (2) pumping the mixed solution into a fluorine gas stripping tower or an anhydrous sodium sulfate drying tower to remove water in the mixed solution by the fluorine gas stripping tower or the anhydrous sodium sulfate drying tower; (3) pumping the mixed solution into a mixed acid kettle, and simultaneously pumping in fuming sulfuric acid to further remove water in the mixed solution; (4) pumping the dehydrated material in the mixed acid kettle into a gas generating tower, heating the gas generating tower to decompose hexafluorophosphoric acid into gaseous PF5 and HF; the gas phase in the gas generating tower enters a rectifying tower after condensation, and phosphorus pentafluoride is obtained through rectification. The present invention improves the reaction yield and significantly shortens the reaction time required, and the new process significantly reduces the usage amount of fuming sulfuric acid, thereby significantly reducing the generation of waste concentrated sulfuric acid.

The invention provides a filtrate reducer and an oil-based drilling fluid as well as a preparation method and application of the filtrate reducer and the oil-based drilling fluid. The preparation method of the filtrate reducer comprises the following steps: mixing acrylonitrile, isobutene and acetone, heating and stirring for a first reaction, and dropwise adding fuming sulfuric acid in the heating and stirring process to obtain a first mixture; mixing N-alkyl acrylamide with the first mixture, and heating for second reaction to obtain a second mixture; dimethylaminoethyl methacrylate and the second mixture are mixed and heated for a third reaction, and a third mixture is obtained; ethyl benzene, carbon tetrachloride and the third mixture are mixed and heated for a fourth reaction, and a fourth mixture is obtained; and extracting and washing the fourth mixture with absolute ethyl alcohol to obtain a white floccule, namely the filtrate reducer. The oil-based drilling fluid comprises an oil phase, bentonite, the filtrate reducer provided by the invention, a flow pattern regulator, a weighting agent and sodium hydroxide. The oil-based drilling fluid provided by the invention has good high-temperature drop filtration performance and is suitable for drilling of deep wells and ultra-deep wells.