Solid amine adsorbent and its preparation method and application

A solid amine adsorbent for CO2 adsorption, comprising:

• modified organic amines and a porous nano carrier;
• wherein a proportion of secondary amines in the modified organic amines is 70% or higher;
• a loading amount of the modified organic amines in the adsorbent is 10 wt. % to 80 wt. %, the modified organic amines are prepared by following steps:
• S1:
• mixing organic amines and organic amine modifiers into a solvent of acetonitrile in a volume of 5-15 times, and stir at a temperature of 25-60° C. at 300-600 rpm for 3-5 minutes until uniformly mixed;
• S2:
• adding a crosslinking agent to the solution and stirring at room temperature at a speed of 300-1500 rpm for 5-20 hours;
• S3:
• during the stirring process at 300-600 rpm, gradually add acetic acid dropwise to adjust the pH of the solution, maintaining it in the neutral range of pH 6.5-7.5, and continue stirring for 15-60 minutes;
• S4:
• using a rotary evaporator to evaporate the solvent at 90-110° C. until completely removed, resulting in the modified organic amine;
• wherein the organic amine modifiers are selected from any one of acetaldehyde, propanal, cyclopentanone, acetone, 3-pentanone, or cyclohexanone;
• the crosslinking agent is selected from any one of triacetoxyborohydride sodium, cyanoborohydride sodium, or borane-2-methylpyridine complex;
• the molar ratio of the organic amine to the organic amine modifying agent is 1:(1-4);
• the molar ratio of the organic amine to the organic amine crosslinking agent is 1:(1-4).