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CN-121974818-A - High-purity oxamide with concentrated particle size and spherical morphology, preparation method thereof and application thereof in preparation of slow release fertilizer

CN121974818ACN 121974818 ACN121974818 ACN 121974818ACN-121974818-A

Abstract

The invention discloses high-purity oxamide with concentrated particle size and spherical morphology, a preparation method thereof and application thereof in preparing a slow release fertilizer, and belongs to the technical field of oxamide synthesis and application. The method comprises the steps of mixing an ammonia alcohol solution and an alcohol ester solution, conveying the mixture into a series tubular reactor for reaction, stabilizing pressure and equalizing flow, conveying the mixture into a parallel tubular reactor for reaction to obtain a reaction solution containing oxamide, carrying out flash evaporation on the reaction solution to obtain a flash evaporation liquid and flash evaporation gas, carrying out solid-liquid separation on the flash evaporation liquid to obtain solid oxamide and filtrate, and drying the solid oxamide. The method realizes high conversion rate and high purity, and the product presents superfine particle size distribution. The prepared oxamide has the purity of more than or equal to 99 percent, the D50 particle size is concentrated by 50+/-15 mu m, the spherical morphology and the uniform morphology are realized, the release is stable, and the oxamide has good effects in the preparation of long-acting slow-release fertilizers, combustion inhibitors and nitrogen utilization rate research.

Inventors

  • WANG JINGYAN
  • Xiu Diekun
  • YU HUAFENG
  • TANG HUI
  • SHAO YUXIANG
  • LI JINGJING

Assignees

  • 上海宜高化学技术有限公司

Dates

Publication Date
20260505
Application Date
20260403

Claims (10)

  1. 1. The preparation method of the high-purity oxamide with concentrated particle size and spherical morphology is characterized by comprising the following steps of: (1) Dissolving ammonia gas in alcohols to obtain an ammonia alcohol solution; (2) Mixing alkyl oxalate with alcohol to obtain alcohol ester solution; (3) Mixing an ammonia alcohol solution and an alcohol ester solution, then conveying the mixed solution into a series tubular reactor for reaction, and then conveying the mixed solution into the parallel tubular reactor for reaction after pressure stabilization and flow equalization to obtain a reaction solution containing oxamide; The mass ratio of the alcohol ester solution to the ammonia alcohol solution is 1 (1-2), the reaction conditions are 30-60 ℃, 0.3-0.8 MPa and 2-6 min; (4) Flash evaporating the reaction liquid to obtain flash evaporation liquid and flash evaporation gas, separating solid from liquid in the flash evaporation liquid to obtain solid oxamide and filtrate, and drying the solid oxamide to obtain the solid oxamide.
  2. 2. The preparation method of claim 1, wherein in the step (1), the concentration of ammonia gas in the ammonia alcohol solution is 6-8.5 mol/L, and in the step (2), the concentration of alkyl oxalate in the alcohol ester solution is 15-40%.
  3. 3. The preparation method according to claim 1, wherein in the steps (1) and (2), the alcohol is one or more of methanol and ethanol, and in the step (2), the alkyl oxalate is one or more of dimethyl oxalate and diethyl oxalate.
  4. 4. The preparation method of claim 1, wherein in the step (3), the mass ratio of the alcohol ester solution to the amino alcohol solution is 1:1.5, and the reaction conditions are 40-50 ℃, 0.4-0.6 MPa and 3-5 min.
  5. 5. The method according to claim 1, wherein in the step (3), the series-connected tubular reactor is composed of a plurality of single tubes connected in series, and the parallel-connected tubular reactor is composed of a plurality of single tubes connected in parallel.
  6. 6. The preparation method of claim 1, wherein in the step (4), the flash evaporation adopts two stages, the temperature of the first stage flash evaporation is 40-50 ℃, the pressure is 0.05-0.1 MPa, the temperature of the second stage flash evaporation is 30-40 ℃, and the pressure is normal pressure.
  7. 7. The method according to claim 1, wherein in the step (4), the drying temperature is 60 to 80 ℃ and the drying time is 0.5 to 2 hours.
  8. 8. The method according to claim 1, further comprising condensing the flash gas in step (4) to recover unreacted alcohol and ammonia, and rectifying and separating the filtrate, recovered alcohol and ammonia, and returning to step (1) and step (2) for recycling.
  9. 9. The high purity oxamide having a concentrated particle size and a spherical morphology produced by the production process of any one of claims 1 to 8.
  10. 10. Use of a high purity oxamide of concentrated particle size, spherical morphology according to claim 9 in any of the following: (a) Use as a nitrogen fertilizer; (b) The application in preparing long-acting slow-release nitrogen fertilizer; (c) Use in studying nitrogen release stability for studying nitrogen release stability; (d) The method is applied to the experimental analysis for researching the nitrogen utilization rate; (e) Use as a combustion inhibitor.

Description

High-purity oxamide with concentrated particle size and spherical morphology, preparation method thereof and application thereof in preparation of slow release fertilizer Technical Field The invention belongs to the technical field of oxamide synthesis and application, and particularly relates to high-purity oxamide with concentrated particle size and spherical morphology, a preparation method thereof and application thereof in preparing slow-release fertilizer. Background Oxamide (Oxamide, OX) is an important organic compound, the molecular formula is C 2H4N2O2, the structural formula is (CONH 2)2), and the oxamide is widely applied to the field of high-end fertilizers because of being one of main raw materials of slow-release fertilizers with high nitrogen content and high-efficiency nitrogen fixation performance. The main method for synthesizing the oxamide at present comprises the steps of 1. A hydrocyanic acid method, wherein the method takes hydrocyanic acid as a raw material to synthesize the oxamide, but HCN is high in cost and a highly toxic chemical, and the industrial production feasibility is poor. 2. According to the ammonium oxalate or urea oxalate pyrolysis method, the ammonium oxalate or urea oxalate is heated and dehydrated to generate the oxamide, but the yield of the oxamide preparation step by the pyrolysis method is only 30-60%, and the method is high in cost and unfavorable for industrialization. 3. An oxalate process which produces oxamides and corresponding alcohols by ammonolysis of oxalate esters. Among them, the preparation of oxamide by reaction of dimethyl oxalate with ammonia is a production method which is common in industry at present. In the eighties of the last century, the Nippon Kongyu product adopts a discontinuous kettle type process to produce oxamide by ammonolysis with dimethyl oxalate as a raw material, thereby realizing the industrial production of the oxamide. The oxamide produced by the method has high purity, but the reaction time is as long as several hours, and the energy consumption of the device is high. The production technology of oxamide has been disclosed in recent years such as patent application CN111153823a, patent application CN113045442a and patent application CN 103242188A. CN113045442a discloses a method for preparing oxamide by using a micro-channel reactor, oxalic ester solution and ammonia water are respectively input into the micro-channel reactor according to a certain proportion, reacted for 5-60 s at the temperature of 0-15 ℃ to obtain oxamide aqueous solution, and redundant ammonia water is removed by continuous distillation. According to the method, although the reaction efficiency is improved by utilizing the microchannel reactor, ammonia water is used as a reactant, the subsequent separation and purification process is complicated due to the aqueous phase reaction, and oxalic ester raw materials are easy to hydrolyze to generate oxalic acid in the reaction process, so that the method is unfavorable for obtaining high-purity oxamide. Patent application CN119455856a discloses a process and a device for producing oxamide, which mix a methanol solution of liquid ammonia with a methanol solution of dimethyl oxalate to generate ammonolysis reaction, flash evaporating, filtering and drying slurry after the reaction to obtain solid oxamide, refining liquid phase to obtain byproduct methanol, and washing and absorbing ammonia in tail gas by dimethyl oxalate and returning the ammonia to a reaction system. The method realizes the high-efficiency utilization of ammonia, adopts the traditional reactor, has limited mass and heat transfer efficiency, high reaction temperature (the temperature is 40-130 ℃ and the pressure is 0.05-2.0 MPaG), and long reaction time (0.2-1 h). Patent application CN115715962a discloses a device and a method for continuously and efficiently preparing oxamide, dimethyl oxalate and liquid ammonia are respectively dissolved in a methanol solvent to carry out liquid phase reaction, the heat of reaction is recovered by arranging a steam drum, and the energy consumption is reduced by adopting a multistage flash evaporation process. However, the method has harsh reaction conditions (the temperature is 100-200 ℃ and the pressure is 1.0-5.0 MPa), the reaction time is longer (10-60 min), and the mass and heat transfer problems in the reaction process cannot be solved. The prior patents CN119455856A and CN115715962A both adopt liquid ammonia as raw materials to prepare an ammonia-alcohol solution with methanol, but because the liquid ammonia is extremely volatile and is in a liquid state at low temperature, uneven mixing with the methanol can cause low ammonolysis reaction efficiency, more byproducts and poor stability. Disclosure of Invention The invention aims to solve the technical problem of providing high-purity oxamide with concentrated particle size and spherical morphology, a preparation method thereof and application thereof