202 results about "Nitrogen oxide" patented technology

The invention relates to the technical field of pendimethalin wastewater treatment, in particular to a pendimethalin wastewater treatment method which comprises the following steps: step 1, adding ferrous oxide or ferrous hydroxide into wastewater, and adjusting the pH value of the wastewater to be neutral; 2, adjusting the pH value of the primary filtrate to 2-5 by using an inorganic acid, and adding an iron-carbon mixture with the mass ratio of 1: (0.5-2) to carry out an oxidation-reduction reaction; and step 3, introducing the secondary filtrate into 2-5 reaction kettles which are connected in series, and adding hydrogen peroxide for 1-3 times according to the mass ratio of hydrogen peroxide to COD (Chemical Oxygen Demand) of (15-25): 1. According to the pendimethalin wastewater treatment method provided by the invention, the iron-carbon mixture generates a primary battery effect in the solution, nitrate radicals can be quickly reduced into nitrogen oxides or ammonia gas, the nitrate radicals are efficiently and quickly treated, and meanwhile, iron ions and ferrous ions can finally generate corresponding hydroxides to be separated out.

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.

A method for the preparation of carboxylic acid esters by iron-catalyzed oxidation esterification of alcohols. The present invention discloses a method for directly oxidizing and esterifying alcohols to prepare carboxylic acid ester compounds with oxygen or air as the oxidant under iron catalysis. The method is carried out at 25 °C - 60 °C in an organic solvent, using iron nitrate (Fe(NO3)3·9H2O), nitrogen oxides and Lewis acid as catalysts, and oxygen or air as the oxidant, and the alcohol is directly oxidized and esterified to form carboxylic acid ester compounds. The present invention has many advantages such as simple operation, cheap and easily available catalysts and raw materials, mild reaction conditions, excellent yield, good compatibility of substrate functional groups, scalable reaction scale, environmentally friendly reaction process and no pollution, and has the prospect of industrial application.

The invention relates to the technical field of chemical plant smoke filtering, in particular to a chemical plant discharge filtering device with a monitoring function, which comprises a barrel, a gas inlet pipe, a gas outlet pipe and the like, the barrel is communicated with the gas inlet pipe, and the top of the barrel is communicated with the gas outlet pipe. Indexes of pollutants such as sulfur dioxide, nitric oxide, carbon monoxide and carbon dioxide in flue gas can be detected through the flue gas sensor, when the flue gas sensor detects that the pollutants in the flue gas exceed the standard, the controller can control an electric guide rail to work, the electric guide rail drives a first push plate to move forwards, and a first sealing plate can also move forwards; the first sealing plate seals the exhaust pipe, real-time response can be achieved after the filter element is aged and breaks down, the filter element is replaced without shutdown under the condition that it is ensured that smoke does not leak, smoke which is not completely purified is prevented from being exhausted out, and therefore pollution to the environment can be avoided.

Aiming at the problems of large flue gas nitrogen oxide generation amount, easy exceeding and serious pollution possibly existing in ammonia gas blending combustion, the invention provides an ammonia gas out-of-furnace bypass combustion blending combustion oxidation method, which comprises the following steps: preparing NO2 by virtue of an ammonia combustion system, generating O.free radicals by virtue of photo-thermal cracking of NO2, oxidizing NO in flue gas into NO2, cracking NO2 into N2, removing NO by virtue of NO2, and performing denitration by virtue of denitration, so that the nitrogen oxide in the flue gas is not easily generated. According to the method, SO2 is oxidized into SO3 through O.free radicals, the SO3 reacts with calcium for desulfurization, CO and VOCs are oxidized into CO2 and H2O, collaborative purification of multiple pollutants is achieved, reduction denitration and wet desulfurization are replaced and used for denitration and desulfurization of combustion flue gas and collaborative treatment of the multiple pollutants, and deep pollution reduction, carbon reduction, energy conservation and efficiency improvement are achieved.

The invention discloses a flue gas distributed denitration process, and belongs to the technical field of fuel gas distributed energy supply. Ammonia gas is added into flue gas at an inlet of a bag-type dust collector and reacts with nitrogen oxide in the flue gas at an active site of a low-temperature denitration catalyst, so that efficient denitration can be realized at a low temperature, and nontoxic and harmless nitrogen and water are generated; reheating denitration is not needed; according to the low-temperature denitration catalyst, cerium nitrate and manganese nitrate are impregnated into mesoporous pores of mesoporous titanium dioxide submicrospheres through vacuum impregnation, glucose serves as a carbon source, p-phenylenediamine serves as a nitrogen source, and manganese cerium / nitrogen-doped titanium dioxide microspheres are obtained through hydrothermal carbonization. And then MOF-tungsten is dispersed in silicon dioxide sol to coat the manganese cerium / nitrogen-doped titanium dioxide microspheres, so that the manganese cerium / nitrogen-doped titanium dioxide microspheres have good compressive strength, wear resistance and denitration efficiency, have excellent ammonium bisulfate decomposition capability and are not easy to block.

Provided in the present application is a compound represented by formula (I), or an enantiomer, a diastereoisomer, a racemate, a tautomer, a stereoisomer, a geometric isomer, a nitrogen oxide, a metabolite or a pharmaceutically acceptable salt, an ester, a solvate, a hydrate, an isotope-labeled compound or a prodrug thereof. The compound represented by formula (I) of the present application has a relatively ideal inhibitory activity with regard to KAT6A and / or KAT6B.

The present application relates to a kind of carbon monoxide sensor with resistance to multiple gas and detection method, belong to coal mine environment gas detection sensor field.The present application includes carbon monoxide sensor, and the method of gas detection of the sensor.Therein, sensor mainly includes carbon monoxide / hydrogen sulfide dual gas detection module, nitrogen oxide detection module, modular mainboard, main shell and main shell display window, wherein carbon monoxide / hydrogen sulfide dual gas detection module and nitrogen oxide detection module measure the gas to be measured.The present application carries out gas concentration value calculation using cross interference compensation algorithm, and the concentration of carbon monoxide gas in coal mine environment is accurately detected by setting different working modes.The present application realizes the real-time monitoring of carbon monoxide, nitrogen oxide and hydrogen sulfide multi-component gas concentration by carbon monoxide, nitrogen oxide, hydrogen sulfide composite electrochemical element design, improves the precise perception ability of intelligent mine, and guarantees coal mine safety production.

The invention relates to the field of nitrogen oxide treatment, and particularly provides preparation and application of a Fe-Mn / NbOPO4 catalyst for improving water resistance and sulfur resistance of NH3-SCR (selective catalytic reduction) reaction. The preparation method comprises the following steps: 1, preparation of an NbOPO4 carrier: mixing and stirring a niobium source and a phosphorus source, dropwise adding ammonia water, filtering and washing to obtain a precipitate, further adding a CTAB / H2O solution, adjusting the pH value with H3PO4, carrying out hydrothermal aging in a reaction kettle, and finally filtering, washing, drying and calcining; and 2, loading Fe and Mn active components, dissolving an iron source and a manganese source in water by adopting a wet impregnation method, adding the NbOPO4 carrier, stirring, carrying out rotary evaporation, drying and calcining. When the air speed is 60000mL. G <-1 >. H <-1 >, the NOx conversion rate in the temperature range of 75-297 DEG C reaches 90% or above, and in a water-resistant and sulfur-resistant performance test of 5vol.% H2O and 100ppm SO2, the reaction activity is almost not obviously reduced. The SCR reaction temperature window of the manganese-based catalyst is widened, the water resistance and sulfur resistance of the manganese-based catalyst are effectively improved, and the manganese-based catalyst has wide application prospects.

Provided herein are methods of depositing molybdenum (Mo) films. The methods involve depositing a thin layer of a molybdenum (Mo)-containing film such a molybdenum oxide, a molybdenum nitride, or a molybdenum oxynitride. The Mo-containing film is then converted to an elemental Mo film. A bulk Mo film may then be deposited on the elemental Mo film. In some embodiments, the process is performed at relatively low temperatures.

The invention discloses a method for preparing 2,2,6,6-tetramethylpiperidine nitroxide free radical compound and a reaction system and the obtained product, the method comprising: adding 2,2,6,6-tetramethylpiperidine to a reactor, adding or not adding an organic solvent and stirring and dissolving; adding a catalyst containing a modified titanium silicon molecular sieve, adding a hydrogen peroxide solution, 2,2,6,6-tetramethylpiperidine and hydrogen peroxide are subjected to an oxidation reaction; the catalyst is removed from the product obtained, and the liquid-phase product is desolvated to obtain 2,2,6,6-tetramethylpiperidine nitroxide free radical compound. The method provided by the present invention prepares 2,2,6,6-tetramethylpiperidine nitroxide free radical compound in a one-step reaction, has a high yield, is easy to purify the product, and has a high purity of the piperidine nitroxide free radical compound product, and the catalyst can be reused.

The invention provides an ammonia gas synthesis method based on an osmium-platinum catalyst and nitrogen oxide, and solves the technical problem of high production cost caused by high price of a catalyst used for hydrogen reduction of nitrogen oxide in the prior art. The method comprises the following steps: respectively preparing NO, H2 and inert gas according to preset requirements; weighing an osmium-platinum catalyst, and adding the osmium-platinum catalyst into the tubular reactor containing the quartz wool; h2 is introduced into the tubular reactor, the reactor is heated to 200-400 DEG C, the osmium-platinum catalyst is pretreated at the temperature, and then the osmium-platinum catalyst continues to be cooled to the room temperature under purging of H2; meanwhile, NO, H2 and inert gas are introduced into the reactor to form mixed gas, the temperature in the tubular reactor is raised to a preset temperature, then heat preservation is conducted, the mixed gas reacts under the action of the osmium-platinum catalyst, and then ammonia gas can be synthesized. The method has lower energy consumption and higher yield, and the used catalyst is lower in cost and better in performance.

Provided are a compound for recoverying a p53 mutation function and use thereof, particularly relating to a compound represented by Formula M, or an enantiomer, a diastereomer, a racemate, a tautomer, a stereoisomer, a geometric isomer, a crystal form, a nitrogen oxide, a metabolite or pharmaceutically acceptable salt, ester, solvate, hydrate, isotope-labeled compound or prodrug of the compound.

The present invention relates to the technical field of phosphorus-nitrogen synergistic flame retardant materials, and particularly relates to triazine ring compounds, preparation methods, triazine ring phosphorus-containing flame retardants and applications. The chemical structure of the triazine ring compound simultaneously has a phosphorus-containing group and a nitrogen-containing group. During the combustion process, the phosphorus-containing group forms P· radicals and PO· radicals, which quench H· and HO· radicals in the gas phase, having a gas-phase flame retardant effect. At the same time, the phosphorus-containing group is further oxidized to form phosphoric acid, promoting the formation of a dense carbon layer in the polymer matrix, achieving the effect of condensed-phase flame retardancy; the nitrogen-containing group can form non-combustible components such as ammonia and nitrogen oxides during the combustion process, effectively reducing the concentration of oxygen and combustible gases in the combustion area, achieving the purpose of gas-phase flame retardancy; the phosphorus-containing group and the nitrogen-containing group can exert the phosphorus-nitrogen synergistic flame retardant effect, thereby achieving the purpose of high-efficiency flame retardancy.

The invention relates to the technical field of flue gas multi-pollutant synergistic purification, in particular to a preparation method of an ultralow-temperature denitration and decarbonization catalyst and application of the ultralow-temperature denitration and decarbonization catalyst to synchronous removal of nitrogen oxides and carbon monoxide in industrial flue gas. The catalyst is prepared by a two-step method comprising the following steps: S1, dispersing a cerium source and a platinum source in absolute ethyl alcohol, and synthesizing a Pt / CeO2 monatomic catalyst by a hydrogen combustion method; s2, compounding an iron source and Pt / CeO2 through a coprecipitation method, drying and calcining in a nitrogen atmosphere to obtain the Fe-Pt / CeO2 composite catalyst. The key process parameters comprise hydrogen / oxygen flow velocity, calcination temperature and mass ratio of the iron source to the carrier. The synergistic removal efficiency of the catalyst on NOx and CO at the ultralow temperature of 50-120 DEG C reaches 85% or above, and the bottleneck that the low-temperature activity of a traditional catalyst is insufficient is broken through; sulfur resistance and water resistance are remarkably improved through the porous structure and the oxygen storage capacity of CeO2, and the activity retention rate is larger than 90% when SO2 and H2O are contained; the device is suitable for high-efficiency purification of complex flue gas of steel, waste incineration and the like, and meets the policy requirements of pollution reduction, carbon reduction and synergistic interaction.

The invention relates to a catalyst for the selective reduction of NOx, based on an IZM-10 AEI zeolite and at least one transition metal, and to its preparation method comprising at least mixing, in an aqueous medium, a FAU-type zeolite having a SiO2 (FAU) / AI2O3(FAU) molar ratio of between 10 and 60 inclusive and a mass percentage of sodium in cation form of less than 0.005%, a nitrogen-containing organic compound R, wherein R is (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form, and optionally sodium hydroxide, until a homogeneous precursor gel is obtained; ii) a hydrothermal treatment step; iii) a step of exchanging at least one ion with a solution comprising at least one species capable of releasing a transition metal; iv) a heat treatment step by drying and calcination.

The present application belongs to the field of denitration agent preparation, and provides a selective non-catalytic reduction denitration agent and a preparation method thereof. First, urea is heat treated to change hydrogen bond strength and intermolecular force in the crystal, and increase thermal motion of urea molecules, so as to cause loose arrangement between molecules, increase exposure of reaction sites, and increase contact area of molecules, thereby increasing reaction rate. A phosphoric acid group is introduced into the urea after heat treatment, and phosphonated urea is formed through chemical reaction, so as to improve adsorption and reaction activity of the urea. This process helps to enhance the combination ability of urea and NOx, thereby improving the denitration efficiency. Appropriate amounts of sodium carbonate, sodium chloride and hydroxyl iron oxide are added to the reaction system, which helps to promote the activity improvement of the denitration agent, and can effectively deal with nitrogen oxide pollution in industrial waste gas.

The utility model discloses a reaction device for normal-pressure leaching of nitric acid, which is characterized in that in the reaction process, nitric oxide in a reaction kettle enters an absorption tower through a nitric oxide exhaust outlet, a first pipeline and a nitric oxide gas inlet, and an oxygen supply device supplies oxygen to the absorption tower; an absorption liquid circulating pump I conveys an absorbent in the absorption tower circulating device to an absorbent circulating inlet I and enters the absorption tower, the absorbent absorbs nitric oxide gas to form nitric acid, nitric oxide released in the process reacts with oxygen to generate nitrogen dioxide, and the nitrogen dioxide reacts with the absorbent to generate nitric acid; according to the device, nitrogen oxide gas generated in the reaction process can be absorbed, the obtained absorption acid (nitric acid) can be cyclically applied to the leaching reaction, and tail gas can be discharged after reaching the standard. And the method is environment-friendly.

The invention relates to a silver-nitrate recovery method comprising the process steps of preparing a nitric-acid solution in a reactor tank and feeding silver sludge into the prepared acid solution to obtain an intermediate product. The silver-nitrate recovery method further comprises introducing N2 onto the intermediate product, sweeping the resulting NOx gases with the introduced N2 and reacting them with H2O2 so as to eliminate them, and collecting the silver nitrate formed in a vessel.

The present invention relates to a process for removing nitrogen oxides, nitrous oxide and carbon monoxide from a gas stream (1), comprising: (a) oxidizing nitric oxide in the gas stream to form nitrogen dioxide by adding an oxygen-containing gas (3) to the gas stream (1), thereby obtaining a nitric oxide-depleted gas stream, and washing the nitric oxide-depleted gas stream with water (7) to obtain a nitric oxide-depleted gas stream (11) to remove nitrogen oxides from the gas stream (1); (b) oxidizing at least a portion of the carbon monoxide in the nitrogen oxide-depleted gas stream (11) to form carbon dioxide, thereby obtaining a carbon monoxide-depleted gas stream (19); (c) converting nitrous oxide in the carbon monoxide-depleted gas stream (19) to nitrogen and oxygen if the carbon monoxide-depleted gas stream (19) does not contain carbon monoxide, or converting nitrous oxide in the carbon monoxide-depleted gas stream to nitrogen and oxygen and / or carbon dioxide if the carbon monoxide-depleted gas stream (19) still contains carbon monoxide, or converting nitrous oxide in the carbon monoxide-depleted gas stream (19) to nitrogen and oxygen and / or carbon dioxide if the carbon monoxide-depleted gas stream (19) still contains carbon monoxide; to obtain a purified tail gas stream (25).

The invention discloses a cobalt-based catalyst for producing ammonia through catalytic oxidation of nitrous oxide and nitric oxide as well as a preparation method and application of the cobalt-based catalyst, and belongs to the technical field of catalysts and environmental pollution. The preparation method of the cobalt-based catalyst comprises the following steps: (1) mixing a cobalt source, a carbon-containing nitrogen compound, a precipitator and a solvent for reaction to obtain a precursor solution; (2) putting the precursor solution into a high-pressure reaction kettle for hydrothermal reaction to obtain a solid, namely a precursor; and (3) performing pyrolysis treatment on the precursor in an inert atmosphere to obtain the cobalt-based catalyst. The cobalt-based catalyst prepared by the invention is applied to electrocatalytic conversion from N2O to NH3 for the first time, and shows excellent catalytic activity.

To provide a memory device having a switching element with excellent characteristics. [Solution] The memory device of the embodiment includes a memory cell comprising: a first conductive layer; a second conductive layer; a third conductive layer between the first and second conductive layers; a switching layer between the first and third conductive layers; and a resistive switching layer between the third and second conductive layers. The switching layer comprises an oxide, nitride, or oxynitride of a first element selected from the group consisting of Al, Si, Ge, Zr, Y, Ta, La, Ce, Ti, Hf, and Mg; a second element, different from the first element, selected from the group consisting of Al, Zn, Sn, Ga, and In; and a third element selected from the group consisting of Te, S, Se, and Sb. The switching layer includes a first region and a second region, wherein the sum of the atomic concentrations of the second element and the third element in the first region is greater than the sum of the atomic concentrations of the second element and the third element in the second region.

The invention belongs to the technical field of adsorption materials, and particularly relates to a hydroxyl-free lead dioxide-based nitric oxide absorbent and a preparation method thereof. The method comprises the following steps: preparing a mixed solution of perchloric acid and lead perchlorate, standing to form a saturated solution, and performing electrodeposition by using the saturated solution as an electrolyte to obtain a lead dioxide deposition layer; and cleaning, drying and crushing the sediments, drying the sediments in an air dry oven with an air exchange function, and calcining the sediments at high temperature to form a target product. The obtained absorbent has the characteristics of hydroxyl-free structure, nanoscale particle size, high porosity, excellent adsorption performance and the like. Test results show that the absorbent has good selective adsorption capacity on NO2, and the adsorption efficiency can reach 85% or above. The material is suitable for nitrogen oxide interference absorption in the determination process of the hydrocarbon content in coal, and has important application value.

The present application belongs to the technical field of inorganic material synthesis, and provides an octahedral nano magnesium oxide, a preparation method and application thereof. The preparation raw materials (hydrated magnesium salt and a precipitating agent (including one or more of urea, hexamethylenetetramine and ethanolamine)) are heated at 25-95 DEG C to obtain a reaction liquid, the reaction liquid is subjected to hydrothermal reaction, the obtained gel intermediate is directly calcined to obtain the octahedral nano magnesium oxide. The present application strictly controls the ratio of water to magnesium in the reaction liquid to be ≤130 mL:1 mol, and the one-dimensional nano structure intermediate product can be obtained through hydrothermal reaction; the one-dimensional nano structure intermediate product is calcined to form the octahedral structure [(100) crystal surface] with the lowest energy and the most stable structure; the precipitating agent forms ammonium radical in the hydrothermal reaction, the ammonium radical escapes in the form of nitrogen oxide or ammonia gas, which enriches the pore structure of the octahedral nano magnesium oxide and improves the specific surface area thereof.

This invention discloses an integrated treatment method for desulfurization, denitrification, and waste heat recovery of coke oven flue gas, belonging to the field of coke oven flue gas treatment technology. The method includes: 1) flue gas pretreatment and high-temperature waste heat recovery; 2) directional oxidation conversion of nitrogen oxides and removal of residual oxidants; 3) synergistic desulfurization and denitrification treatment with activated carbon / activated coke; 4) side reaction suppression and control; 5) low-temperature waste heat recovery and reheat utilization; and 6) activated carbon / activated coke regeneration and sulfur resource recovery. This invention converts NO in flue gas into high-valence NO₂ through a pre-oxidation reaction, improving the kinetics of the denitrification reaction, increasing denitrification efficiency, and reducing ammonia consumption. By controlling the SO₂ concentration and acid gas content at the desulfurization layer outlet, it effectively inhibits the deposition of ammonium salts such as (NH₄)₂SO₄ and NH₄Cl, reducing bed blockage. Through high and low temperature staged waste heat recovery, it achieves tiered utilization of heat, improving the overall thermal efficiency of the system. This achieves synergistic optimization of efficient pollutant removal and efficient energy utilization.

This invention discloses a room-temperature phase pyroelectric material and its preparation method, relating to the field of pyroelectric material technology, with the chemical formula C4H. 14 N₂OPbCl₄ is prepared as follows: 2-Dimethylaminoethylamine is cooled and stirred in an ice-water bath, then hydrogen peroxide solution is added dropwise while stirring. After the reaction, the resulting reaction solution is vacuum dried to obtain the nitrogen oxide of 2-dimethylaminoethylamine. The nitrogen oxide of 2-dimethylaminoethylamine and lead chloride are added to a concentrated hydrochloric acid solution, heated in an oil bath, and stirred to obtain a pyroelectric material. The pyroelectric material of this invention has a perovskite structure and undergoes a reversible phase transition reaction at a phase transition temperature of 27°C. During the phase transition, a current is generated at the polar axis of the crystal. The phase transition temperature at room temperature allows the pyroelectric material to operate within a relatively stable temperature range, providing reliable energy collection performance and showing great application value in waste heat utilization, self-sustaining systems, and other fields.

The invention belongs to the technical field of organic synthesis, and discloses ketoxime ether as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a ketoxime compound, tert-butyl alcohol and alkali to obtain a mixed solution; and adding a methylation reagent into the mixed solution, and reacting to obtain ketoxime ether. The preparation method is low in raw material cost and simple in process operation; tert-butyl alcohol is used as a solvent, sodium tert-butoxide is used as an alkali source, no water participates in the reaction process, ketoxime hydrolysis is effectively reduced, side reactions are greatly reduced, the yield of the obtained product is high, and subsequent separation and solvent recycling are facilitated; use of toxic substances such as sulfur dioxide and sodium nitrite is avoided, and emission of toxic gases such as nitrogen oxides is reduced; and the process safety risk is reduced, and the method is safe, reliable, simple and feasible.

The invention relates to the technical field of synthesis of chlorine-containing pyridine intermediates, and discloses a method for synthesizing 2, 3, 4, 5-tetrachloropyridine by using 2, 5-dichloropyridine, which comprises the following steps: step 1, preparation of 2, 5-dichloropyridine nitrogen oxide: taking 2, 5-dichloropyridine as a raw material, reacting in the presence of a catalyst and acetic acid, and then filtering to remove the catalyst to obtain 2, 5-dichloropyridine nitrogen oxide; adding an acetic acid solution of 2, 5-dichloropyridine nitrogen oxide; step 2, nitration reaction: adding sulfuric acid and nitric acid, and reacting to obtain 2, 5-dichloro-4-nitropyridine nitrogen oxide; step 3, nitrogen and oxygen removal reaction: adding acetyl chloride to replace 4-position nitro to obtain 2, 4, 5-trichloropyridine nitrogen oxide, and then adding phosphorus trichloride to remove nitrogen and oxygen to obtain 2, 4, 5-trichloropyridine; and 4, chlorination and refining: adding Lewis acid into the 2, 4, 5-trichloropyridine, reacting to obtain a 2, 3, 4, 5-tetrachloropyridine crude product, and refining the crude product to obtain the finished product 2, 3, 4, 5-tetrachloropyridine. The invention solves the problems of more byproducts and unsatisfactory product purity and yield in the prior art.

The invention provides a preparation method of urea, which comprises the following steps: forming an electrode pair with a first counter electrode by taking a solution containing carbon dioxide and nitrogen oxide salt as a first electrolyte and a first working electrode as a cathode, a working voltage of-0.7 V to-1.0 V is applied to the first working electrode, so that carbon dioxide and the nitric oxide-containing salt in the electrolyte are subjected to a co-reduction reaction to obtain urea, and byproducts of carbon monoxide and ammonia are generated; a reaction solution after the co-reduction reaction is completed is used as a second electrolyte, a second working electrode is used as an anode to form an electrode pair with a second counter electrode, a working voltage of 0.6-0.9 V is applied to the second working electrode, so that carbon monoxide and ammonia in the second electrolyte are subjected to a co-oxidation reaction to obtain urea, and by-products carbon dioxide and nitrogen-containing oxide salt are generated; and taking the reaction liquid after the co-oxidation reaction as a first electrolyte, and alternately and repeatedly carrying out the co-reduction reaction and the co-oxidation reaction. The conversion rate of the urea prepared by the preparation method is high.

The present invention discloses a chiral nitrogen oxide compound, its preparation method, and application, belonging to the fields of organic synthesis technology and pesticide antibacterial activity research technology. The present invention discloses a method for preparing chiral nitrogen oxide compounds from nitrogen oxides and bromocinnamaldehyde, and synthesizes a series of compounds. The derivatives have good universality, excellent yields (up to 86%), enantioselectivity (up to 96%), and good biological activity, which is of great research significance for the further development and utilization of chiral nitrogen oxide compounds.