3539 results about "Side product" patented technology

The invention belongs to the technical field of PET (Polyethylene Terephthalate) recovery, and particularly relates to a method for assisting methanol alcoholysis of waste PET by using an ester solvent. The method comprises the following steps: by taking waste PET as a raw material, methanol as a solvent and an ester solvent as a cosolvent, catalyzing and depolymerizing the waste PET under the action of an organic strong alkali catalyst to obtain an alcoholysis product, and further separating and purifying the alcoholysis product to obtain DMT and high-value byproducts. The method is mild in reaction condition and rapid in reaction process, the catalyst does not contain metal, and the subsequent purification process can be simplified.

The invention provides a novel acrylonitrile catalyst and a preparation method thereof. The novel acrylonitrile catalyst is prepared from the following raw materials: mixed salt, an active component, silica sol, a rare earth precursor, a carrier and a cosolvent, by introducing the cosolvent and optimizing the carrier structure, the dispersity of the rare earth precursor is improved, the production process is optimized, the doping efficiency of the rare earth precursor is remarkably improved, the activity, selectivity and stability of the novel acrylonitrile catalyst are improved, generation of by-products CO, CO2, acrolein and acrylic acid during acrylonitrile production can be reduced, and industrial efficient preparation is achieved.

The invention discloses a polyimidazolone compound as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving a bilateral alkyne ester compound, amidine hydrochloride, a catalyst and a desalting agent in an organic solvent, and carrying out polymerization reaction to obtain the polyimidazolone compound. The polyimidazolone compound with the five-membered ring is selectively generated, and the method has the advantages that monomers are easy to obtain, operation is easy, and by-products are low in toxicity. The polyimidazolone compound prepared by the invention has better machinability and has potential application value in the aspects of metal ion detection and biogenic amine detection.

The invention discloses a multifunctional composite material for mineralizing and storing CO2 based on fly ash and a preparation method of the multifunctional composite material. The material is prepared from high-activity fly ash subjected to plasma activation treatment, a nanoscale metal oxide catalyst, a metal organic framework, a functional organic ligand, an intelligent pH regulator, a solid suspension stabilizer and water. The preparation method comprises the steps of suspension preparation, high-pressure CO2 mineralization reaction in a reaction kettle, centrifugal separation and freeze drying treatment. The method is simple, the raw material cost is low, the prepared multifunctional composite material not only can remarkably improve the storage efficiency of CO2, but also can ensure that a stable carbonate product is generated, and the carbonate product has high specific surface area and excellent chemical stability, can be widely applied to the fields of high-end building materials, energy storage materials and fine chemical engineering, and has wide application prospects. And meanwhile, the high-added-value utilization of the industrial by-product fly ash is realized, and the dual purposes of reducing carbon emission and improving the utilization rate of solid wastes are achieved.

The invention relates to the technical field of preparation of iron phosphate materials, in particular to a method for doping iron phosphate with titanium, which comprises the following steps: 1, dissolving a titanium dioxide by-product ferrous sulfate powder in water to prepare a titanium-containing iron source solution; 2, adding water into the reaction kettle, and stirring; 3, adding the titanium-containing iron source solution, the phosphorus source solution, ammonia water and an oxidizing agent into a reaction kettle to prepare primary slurry; 4, carrying out filter pressing on the primary slurry, washing until the conductivity is less than or equal to 2000us / cm, and then adding water to prepare secondary slurry; 5, phosphoric acid is added into the reaction kettle for bottoming, and the temperature is increased to 60-70 DEG C; 6, adding the secondary slurry into the reaction kettle, and carrying out heat preservation reaction on the secondary slurry and phosphoric acid; and 7, filtering the reaction product obtained in the step 6, washing until the conductivity is less than or equal to 500us / cm, and then drying and sintering. According to the method, the titanium doping technological process is simplified, and meanwhile the titanium element utilization rate in the titanium dioxide by-product and the purity of the titanium-doped iron phosphate product are improved.

The invention relates to the technical field of purification of organic chemicals, in particular to an aroma purification method of leaf alcohol. Comprising the following steps: preparing a methanesulfonic acid magnetic catalyst; esterification of leaf alcohol; and alcoholysis and fractionation of the esterification solution. According to the method, acetic acid is used for esterification of leaf alcohol, then clear water and a sodium carbonate solution are used for washing, the clear water can effectively remove some water-soluble impurities and acidic byproducts, and the sodium carbonate solution not only can neutralize residual acidic substances, but also can promote siloxane impurities in initial leaf alcohol to be hydrolyzed and then taken away by a water phase, so that the content of the siloxane impurities in the leaf alcohol is reduced; in the subsequent process of producing leaf alcohol through alcoholysis of the organic phase I, pure water and ethanol, silyl ether impurities are hydrolyzed in a high-temperature and strong-alkali environment, products are dissolved in waste liquid to be removed, olefine aldehyde impurities with the boiling point lower than that of leaf alcohol are removed through azeotropic fractionation with ethanol, in conclusion, the impurities in the finished product leaf alcohol can be effectively reduced, and the yield of the finished product leaf alcohol is increased. And the prepared finished product leaf alcohol is high in purity and pure in fragrance.

The invention discloses a supported nickel catalyst for preparing 1, 3-propylene glycol through hydrogenation of 3-hydroxypropionaldehyde as well as a preparation method and application of the supported nickel catalyst, and relates to the technical field of catalysts. The modified long-chain multi-carbon inducer is used, and a special long-chain molecular structure and a branched chain group of the inducer can effectively and selectively adsorb and occupy a micropore impregnation site; the preparation method has the beneficial effects that more active component nickel species are obviously promoted to be dispersed in main reaction confinement spaces such as mesopores and macropores and interact with the carrier to form effective active sites, and active component steeping liquor is inhibited from entering micropore channels due to capillary action; the active site failure caused by agglomeration of nickel species in micropores in the subsequent drying and roasting process of the catalyst precursor is avoided, the efficient and directional reaction is ensured, the generation of by-products is greatly reduced, the pressure is relieved for the subsequent product rectification separation, and the final product purity is improved. The catalyst provided by the invention can still keep an excellent catalytic effect when the air speed of a 3-hydroxypropionaldehyde solution is increased to 6.5 h <-1 >.

The invention relates to a self-repairing concrete complexing agent and a preparation method thereof, and belongs to the technical field of concrete.The self-repairing concrete complexing agent is prepared from 1-4 parts of microorganism induction repairing agent, 2-6 parts of nanometer wollastonite, 10-15 parts of slow-release repairing liquid and 0.02-0.12 part of magnesium oxide. Triple repair mechanisms of microbial mineralization, chemical gel and nano-filling are fused, crack initiation and expansion to a stable whole stage are covered, the repair system is far better than a single repair system, the slow release liquid realizes on-demand release of the repair agent, one-time consumption failure is avoided, durability is improved by 50% or above, nano wollastonite and magnesium oxide micro-expansion synergistically enhance compactness, and the repair effect is good. Meanwhile, the method is compatible with an existing concrete production line, complex equipment is not needed, energy consumption is reduced, the use amount of components is small, microbial metabolism and natural minerals are further utilized, pollution of chemical expanding agents is reduced, only water triggering is needed in the repairing process, no toxic by-product is generated, and the method meets the green building material standard.

The invention discloses a multifunctional cellulolytic enzyme and application thereof in degradation of agricultural by-products, and belongs to the technical field of biology. The multifunctional cellulolytic enzyme is named RuCelI, and the amino acid sequence of the multifunctional cellulolytic enzyme is as shown in SEQ ID NO. 1. Based on a rumen microbial metagenome resource mining technology, a novel multifunctional cellulose decomposition enzyme RuCelI is developed, and the enzyme has double activities of endo-cellulase and xylanase, can be used for degrading agricultural by-products, reducing the treatment cost and improving the degradation efficiency, and is beneficial to improving the utilization rate and the economic benefit of the agricultural by-products.

The invention provides a preparation method of 3-boron-L-phenylalanine or a derivative of 3-boron-L-phenylalanine. The preparation method provided by the invention comprises the step of preparing 3-boron-L-phenylalanine as shown in a formula (VI) or a derivative thereof by taking a compound as shown in a formula (III) as a raw material. The method has the advantages of mild reaction conditions, short route, high yield, few byproducts and low cost, and does not need an extremely low temperature condition process or complicated purification steps. # imgabs0 #

The invention provides a catalyst, a preparation method and application thereof, and a method for preparing primary amine by catalyzing nitrile compound hydrogenation, and particularly relates to the technical field of catalyst synthesis. The catalyst comprises a nickel / cobalt-based catalyst and a metal salt; wherein the nickel / cobalt-based catalyst is selected from any one of a supported nickel / cobalt-based catalyst, a Raney nickel / cobalt catalyst or a nickel / cobalt nanocrystal; the metal salt comprises any one or a combination of at least two of tungsten salt, molybdenum salt, vanadium salt, aluminum salt and cerium salt. The metal salt and the nickel / cobalt main catalyst have a synergistic effect: the surface electron density is adjusted through electron transfer, the hydrogen dissociation and cyano adsorption activation capacities are enhanced, the hydrogenation activity is improved, and the mild condition reaction is assisted; the surface chemical environment is changed or steric hindrance is borrowed, the primary amine selectivity is improved, and byproducts are inhibited; aluminum salt, cerium salt and the like inhibit nickel / cobalt agglomeration, increase active sites, enhance stability, prolong the service life and reduce the dosage.

The invention relates to the field of caprolactam production, and discloses a green and efficient production process and device. The process comprises the following steps: continuously oximating cyclohexanone and hydroxylamine in a microreactor under the catalysis of mesoporous silica solid acid; carrying out gas phase rearrangement on cyclohexanone-oxime in the presence of a ZSM-5 molecular sieve under the assistance of microwaves; coupling, rectifying and purifying the crude product through a four-stage molecular sieve membrane; and performing catalytic cracking on the by-product to obtain N2 / H2O and recycling. The device comprises a micro-reaction unit, a microwave-radial reactor, a membrane coupling rectifying tower group and a tail gas cracking unit. Zero emission of ammonium sulfate is achieved, the product purity is larger than or equal to 99.95%, and energy consumption is reduced by 45%.

The invention belongs to the technical field of polyfluorosiloxane synthesis, and provides a low-by-product polyfluorosiloxane controllable synthesis method which comprises the following steps: carrying out anionic ring opening polymerization on D3F by adopting a binary organic catalytic system, weakening the strong nucleophilicity of an active center based on hydrogen-bond interaction and steric effect, and inhibiting the occurrence of chain back-biting side reaction, so as to obtain the low-by-product polyfluorosiloxane. The polyfluorosiloxane with low content of by-product DnF (n is greater than or equal to 4), controllable structure and narrow molecular weight distribution is prepared. The polyfluorosiloxane with low byproduct content is catalyzed by the binary organic catalyst, the synthesis method is simple, the operation is convenient, the reaction condition is mild, the catalyst has good stability, large-scale production is easy, and further development of the polyfluorosiloxane in the field of high-end and harsh oil-resistant sealing materials can be promoted.

The invention relates to the technical field of high polymer materials, and discloses a method for continuously producing brominated polystyrene, which comprises the following steps: I, preparing raw materials, ensuring the basic quality of the product by high-quality raw materials, and optimizing reaction conditions, improving the yield and reducing unnecessary byproducts by correct selection; step II, premixing and heating, full premixing ensures the consistency of the materials, and more uniform reaction can be realized. According to the method for continuously producing brominated polystyrene, continuous supply of materials is ensured by utilizing an automatic storage and conveying system, uniform dispersion and stable temperature rise of the materials are ensured by adopting a continuous feeding mixer and an indirect heating system, and efficient bromination reaction is performed by using a microchannel reactor; products are rapidly separated and purified by means of a continuous centrifugal separator and a membrane separation technology, and an automatic quality control system is combined with multiple analytical instruments to ensure that the quality of each batch of products is consistent, so that the effect of efficient, stable and continuous production can be achieved.

The invention discloses a preparation method of pyridinetriazolone, and belongs to the technical field of organic synthesis, and the preparation method comprises the following steps: taking hydrazine hydrate as a starting raw material, adding urea in batches at the temperature of 80-85 DEG C, carrying out heat preservation reaction to obtain semicarbazide, dropwise adding hydrochloric acid to form salt, and drying under reduced pressure to obtain semicarbazide hydrochloride; adding the semicarbazide hydrochloride obtained in the previous step and 2-chloropyridine into an ethylene glycol monomethyl ether system, heating to 130-135 DEG C, refluxing, adding a catalytic amount of concentrated sulfuric acid, and carrying out heat preservation reaction to obtain pyridine triazolone; and drying the post-treated mother liquor under reduced pressure, weighing, adding quantitative urea, heating to 130-135 DEG C, and reacting to obtain the pyridinium triazolone. The initial raw materials are hydrazine hydrate and urea, are common industrial raw materials, are easy to obtain and low in price, and are beneficial to industrial production; the by-product 2-hydrazinopyridine is recovered and reacts with urea to prepare the pyridintriazolone, so that the raw material utilization rate and the product yield are greatly improved, the total yield reaches more than 80%, and the purity of the pyridintriazolone is more than or equal to 99.0%.

The invention provides a method for preparing high-purity phosphatidylserine by a batch enzyme catalysis method based on dynamic choline removal, and belongs to the technical field of enzymatic reaction. According to the method disclosed by the invention, in a reaction system for preparing phosphatidylserine, a byproduct choline is selectively adsorbed by adopting resin. Choline in a reaction system is removed in real time through the integrated adsorption separation module, the enzyme inhibition problem is solved, and meanwhile, the PC conversion rate is larger than or equal to 98% and the PS purity is larger than or equal to 96% in combination with the immobilized enzyme circulation technology; the enzyme can be reused for more than or equal to 20 times (activity retention is more than or equal to 90%); and the choline residual concentration is less than or equal to 0.5 mM (an inhibition threshold value or less).

The invention relates to the technical field of organic synthesis, in particular to a method for homogeneous catalytic synthesis of dimethyl carbonate by using a liquid separation method to separate a catalyst, which comprises the following steps: by using 0.3-15% long-chain tertiary amine as a homogeneous catalyst, carrying out homogeneous reaction on cyclic carbonate and methanol in a mass ratio of 1: (1.2-5.5) at 60-80 DEG C for 4-7 hours. And after the homogeneous transesterification reaction is completed, carrying out atmospheric distillation on the reaction mixture, and collecting fractions to obtain the target product dimethyl carbonate. Carrying out liquid separation on the heterogeneous atmospheric distillation residual liquid, and collecting a lower-layer material to obtain a by-product; and the collected material is a catalyst which can be directly recycled subsequently. The dimethyl carbonate synthesis method provided by the invention has the characteristics of high catalytic efficiency, easy catalyst separation, environmental protection, energy saving and the like.

The invention belongs to the technical field of solid waste utilization, and particularly relates to a modified ZSM-5 molecular sieve catalyst and a preparation method and application thereof. The catalyst comprises a ZSM-5 molecular sieve and an active component, wherein the active component is loaded on the internal pore channel and the surface of the ZSM-5 molecular sieve; the active component comprises one or more of Zn, Fe, Ni, Co, Mo and Zr. By adjusting the loading capacity of the active components and the acidity of the catalyst and adjusting the interaction among the components of the catalyst, the high-density polyethylene plastic is used as a raw material, and the catalyst is simple in structure, single in element, free of oxygen element and low in by-product content; the modified ZSM-5 molecular sieve catalyst is simple in preparation process and low in production cost, and the catalyst takes high-density polyethylene plastic as a raw material, so that the yield of MAHs prepared by directional pyrolysis of the high-density polyethylene plastic as the raw material and the stability of the catalyst are effectively improved.

The invention discloses a bimetallic MOFs mediated morphology-controllable catalyst, a preparation method and application thereof, and the preparation method comprises the following steps: respectively adding an iron salt, a cobalt salt and an organic ligand into an organic solvent, and then adding an alkaline regulator and a surfactant; transferring the stirred solution into a reaction kettle to carry out solvothermal reaction, and centrifuging, washing and drying the suspension after the reaction to obtain a bimetal organic framework (MOFs) precursor; and carrying out heat treatment in a gas atmosphere to obtain the catalyst. The bimetallic MOFs are obtained through a one-step solvothermal method, the size and morphology of the product are regulated through the alkaline regulator, agglomeration of catalyst nanoparticles can be reduced by adding the surfactant, the preparation method is simple, the specific surface area of the product is high, and when the catalyst is used for preparing high-carbon hydrocarbon through catalytic hydrogenation of carbon dioxide, the yield of the product is high. The conversion rate of carbon dioxide reaches up to 47.82%, the selectivity of high-carbon hydrocarbon reaches 59.68%, the selectivity of by-products carbon monoxide and methane is low, and the catalytic activity is good.

The invention discloses a catalytic combustion catalyst for treating CVOCs (Chemical Volatile Organic Compounds) as well as a preparation method and application of the catalytic combustion catalyst. The preparation method comprises the following steps: (1) impregnating and loading cerous nitrate and trimethyl phosphate on a carrier, drying, and roasting at 600-800 DEG C to form a modified carrier containing a cerous phosphate crystal phase; and (2) impregnating and loading active metal ruthenium on the modified carrier, drying and roasting to obtain the catalyst for treating catalytic combustion of the CVOCs. The catalyst provided by the invention can be used for catalytic combustion degradation of CVOCs such as dichloromethane, chlorobenzene, chloroethylene, dichloroethane, dichloroethylene, oxychloropropane and the like. For catalytic combustion degradation of CVOCs, the catalyst disclosed by the invention can show high activity, high chlorine-resistant stability, low polychlorinated by-product selectivity and thermal stability, and has certain industrial application prospects.

The invention belongs to the field of preparation of halogen-containing substituted benzoic acid, and particularly relates to a method for preparing o-chlorobenzoic acid through hydrogenation selective debromination. According to the invention, hydrogen is used as a reducing agent, a palladium catalyst is used as a catalyst, a methanol aqueous solution is used as a solvent, and 2-chloro-3-bromobenzoic acid, 2-chloro-5-bromobenzoic acid or a mixture thereof are used as raw materials to prepare o-chlorobenzoic acid. According to the method, debromination is controlled through selective hydrogenation instead of dechlorination, so that generation of a byproduct benzoic acid is inhibited. The scheme is reasonable in design, simple in process and mild in reaction condition, and a new thought is provided for the synthesis method of o-chlorobenzoic acid.

The invention discloses a preparation method of V-shaped adsorptive starch, and belongs to the technical field of starch modification. The preparation method comprises the following steps: firstly, carrying out high-temperature alcohol-water heat treatment to obtain V-type starch with a V-type single-spiral structure, expanded and loose particles, a large amount of exposed hydroxyl groups and relatively high reaction activity; pullulanase which has a poor enzymolysis effect on original starch and is not applied to enzymolysis of the V-type starch is subsequently adopted for enzymolysis, due to the fact that pullulanase has different enzymolysis characteristics from common saccharifying enzyme and alpha-amylase, short-chain dextrin formed during enzymolysis can be combined with ethyl alcohol to form a V-type compound with an adsorption effect, the V-type compound can be precipitated by the ethyl alcohol, and then the V-type compound can be separated and purified. The utilization rate of enzymolysis byproducts is improved, so that the yield of final products can be improved.

The invention discloses an ether polymerization inhibitor special for a butadiene extraction system and a preparation method of the ether polymerization inhibitor. The ether polymerization inhibitor comprises the following raw materials: a polymerization inhibitor intermediate, a solvent and a dispersing agent, the production process comprises the following steps: preparing a polymerization inhibitor intermediate, preparing a solvent, compounding, feeding and mixing, filtering, removing impurities and detecting. According to the method, firstly, a polymerization inhibitor 701 and diethylene glycol normal pressure etherification process is adopted, and beta-hydroxyethyl methyl ether is introduced to seal a terminal group, so that the power consumption is reduced, the generation of byproducts is inhibited, the solubility of an intermediate acetonitrile is improved to be greater than or equal to 30g / L, and the anti-interference performance is greatly enhanced; the solvent doped with a small amount of silane modified nano diatomite is prepared, impurities can be adsorbed, metal ions can be chelated, the dispersing agent can be assisted to be evenly distributed, the problems that a pure water solvent is single in function and the dispersing agent is prone to agglomeration are solved, and the polymerization inhibition efficiency and the stability of an extraction system are guaranteed.

The invention relates to the field of phosphorus-nitrogen flame retardants, and discloses a preparation method and application of a novel phosphorus-containing nitrogen oxide flame retardant, the preparation method comprises the following steps: S1, under the protection of nitrogen, dissolving diphenylphosphinyl hydroxylamine and triethylamine in a tetrahydrofuran solvent to prepare a reaction substrate solution; s2, slowly dropwise adding a diphenylphosphinyl chloride solution into the solution, and then sufficiently carrying out the reaction in a staged heating and heating reflux mode; s3, cooling and filtering to remove solid byproducts generated by reaction, and concentrating filtrate to obtain a crude product solid; and S4, recrystallizing and purifying the crude product by using ethyl acetate, and finally heating and drying the obtained crystal under a vacuum condition to obtain the product. An N-O group is innovatively introduced into the molecular structure of the flame retardant, so that the effect of efficiently capturing gas-phase free radicals in cooperation with a phosphorus-containing group is achieved, and the substantive technical progress that the material can be endowed with excellent flame retardant property with extremely low addition amount is realized.

The invention discloses an adenosine kinase mutant with high thermal stability and application thereof, and relates to the technical field of enzyme engineering, and the adenosine kinase mutant with high thermal stability is obtained by performing point mutation on the 253rd site or the 82nd site of adenosine kinase as shown in SEQ ID NO: 1. According to the invention, an adenosine kinase mutant is used as a biocatalyst in an enzyme catalysis manner; the method is used for enzymatic synthesis of 5 '-adenylic acid, adenosine and adenosine triphosphate react to prepare adenylic acid, generation of by-products and impurities in the reaction is reduced to a certain extent, production efficiency and purity of adenylic acid are improved, reaction conditions are mild in preparation in an enzyme catalysis mode, pollution to the environment is avoided, and the method is suitable for industrial production. And the high-thermal-stability adenosine kinase mutant is applied to adenylic acid preparation, so that the preparation efficiency and yield of adenylic acid can be improved.

The invention discloses selenium-containing unsaturated polyesteramide and a preparation method thereof, and the preparation method comprises the following steps: mixing and dissolving a diamine compound, propiolic acid ester and selenolactone in an organic solvent, and carrying out chemical reaction to obtain the selenium-containing unsaturated polyesteramide. A diamine compound, propiolic acid ester and selenolactone are used as raw materials, selenium-containing unsaturated polyesteramide is generated through click polymerization reaction of selenol and alkyne, the novel preparation method of selenium-containing unsaturated polyesteramide is developed, and the prepared polyesteramide is narrow in molecular weight distribution, controllable in structure and adjustable in degradation rate, and can be used for preparing selenium-containing unsaturated polyesteramide. Long-term stability is good, multiple responsiveness is achieved, and optical performance is good; the raw materials are wide in source, tedious substrate synthesis is avoided, the steps are simple, the reaction conditions are mild, the polymerization speed is high, and efficient large-scale production can be achieved; no catalyst is needed, no by-product is generated, and extra purification is not needed.

The invention discloses a boron-containing copper-based three-dimensional metal organic framework material as well as a preparation method and application thereof, and belongs to the technical field of fine chemical engineering. The preparation method comprises the following steps: preparing Zn-based MBON from zinc salt, boric acid and imidazole through a hydrothermal method, and then completely replacing the zinc component with copper to obtain Cu-based MBON, namely the boron-containing copper-based three-dimensional metal organic framework material. The specific surface area of the material is large, and a three-dimensional nano flower-shaped unique structure is formed. The prepared material is used as a catalyst for furfural electro-hydrogenation and carbon dioxide reduction reaction, the diffusion efficiency of reactants (such as furfural and CO2) can be enhanced, rapid desorption of products (such as furfuryl alcohol and ethylene) can be promoted through the surface capillary action, meanwhile, generation of by-products caused by excessive reaction is inhibited, and the selectivity of target products is improved.

The invention belongs to the field of chemical engineering manufacturing industry, and relates to equipment and a method for producing cyclic ketone compounds by oxidizing cycloolefin by using waste gas produced by adipic acid. Raw material gas A containing nitrous oxide from an adipic acid production process production line can be subjected to oxygen removal, so that the oxygen content is less than 100ppm; the raw material gas A containing nitrous oxide from the adipic acid production line can also be purified into purer gas containing 50-99% of N2O, and the purer gas is used for reacting with the cycloolefin compound; the reaction equation is CnH2n-2 (cycloolefin) + N2O (nitrous oxide)-> CnH2n-2O (a product cyclic ketone compound) + a byproduct + N2 superscript (nitrogen), wherein n is a positive integer from 4 to 24. The device is stable in consumption quota, low in production cost and high in economic benefit compared with the prior art.

The present invention relates to the technical field of organic synthesis, particularly to a daphnetin preparation method, which comprises: adopting 2, 3, 4-trihydroxybenzaldehyde and Meldrum's acid as starting raw materials, and carrying out a first-step reaction under the action of a first catalyst to obtain an intermediate 7, 8-dihydroxycoumarin-3-carboxylic acid; the intermediate 7, 8-dihydroxycoumarin-3-carboxylic acid is subjected to a second-step reaction under the action of a second catalyst, and daphnetin is obtained. The method has the remarkable advantages that firstly, the reaction process is easy to control, the generation amount of byproducts is low, and the product is excellent in appearance quality and extremely high in purity; and secondly, the use of chemicals with high risk and high toxicity is avoided, meanwhile, a large amount of acid waste liquid is not generated, and the environmental pollution is effectively reduced. In addition, the recycling of the solvent and the catalyst further reduces the production cost. The yield and the purity are remarkably improved, the total yield can reach 90% or above, the purity exceeds 99%, and the method is very suitable for industrial large-scale production.

The invention provides a method for preparing phosphorus pentafluoride, which comprises the following steps: (a) mixing sulfur and phosphorus, and reacting at the temperature of 320-340 DEG C to generate phosphorus pentasulfide; (b) reacting phosphorus pentasulfide with hydrogen fluoride gas at the temperature of 170-190 DEG C, cooling the reaction product to-85 to-60 DEG C, and performing low-temperature rectification separation to obtain pure phosphorus pentafluoride and byproduct hydrogen sulfide; the molar ratio of phosphorus pentasulfide to hydrogen fluoride gas is (1-9.5): 10.2. The phosphorus pentafluoride can be efficiently prepared in an environment-friendly manner by adjusting the reaction conditions and the raw material ratio and reacting the easily available raw materials; and moreover, an electrolysis technology is further introduced to treat the hydrogen sulfide byproduct, so that the purity and efficiency of sulfur recovery are optimized, the purposes of environment-friendly and efficient recovery and utilization of the byproduct are achieved, the overall economical efficiency and safety of the process are improved, and the whole process chain is further perfected.