Step 1. Obtain a mixture of acrylonitrile and dimethylamine in a molar ratio of 1:1 to 3, and vaporize the mixture at a temperature of 100 to 120°C to obtain a primary vaporized mixture;
Step 2. The amination reaction is carried out with the primary vaporization mixture under the action of a portion of the activated carrier. The reaction temperature is 100-120° C., the reaction pressure is 0.3-0.5MPa, and the volumetric space velocity of acrylonitrile is 0.1-0.25h-1. Obtain a catalytic mixture;
Step 3. The primary catalytic mixture is vaporized at a high temperature under the condition of 150-180 °C to obtain a secondary vaporized mixture;
Step 4. The secondary vaporization mixture is subjected to hydrogenation reaction under the action of another activated carrier, the reaction temperature is 150-180°C, the reaction pressure is 0.3-0.5MPa; the volume space velocity is 0.1-0.25h-1, and the secondary catalyst;
Step 5, the secondary catalyst is cooled to 40° C., and the liquid phase is collected, and the liquid phase is specifically N,N-dimethyl-1,3-diaminopropane.
A method for preparing 3-Dimethylaminopropylamine, the method comprises the following steps:
a) Add acrylonitrile into the synthesis kettle, control the temperature to 120℃, add dimethylamine under the condition of stirring and cooling water circulation cooling, remove dimethylamine through vacuum distillation, pressure 0.03MPa, and prepare N,N-dimethylamine Methylaminoacrylonitrile; the molar ratio of acrylonitrile to dimethylamine is 1:1;
b) Add the 3-Dimethylaminopropylamine obtained in step a) into the autoclave, add a hydrogenation catalyst, feed liquid ammonia into the autoclave, heat up to 80°C, keep the pressure at 2.5MPa, and feed hydrogen , stirring while maintaining the temperature at 80 ° C, the reaction, the initial distillation after sedimentation, rectification to obtain N,N-dimethyl-1,3-propanediamine, and then storage tank packaging; hydrogenation catalyst and N,N-dimethyl The molar ratio of propionitrile is 10:1; in the initial distillation, the fraction with a temperature greater than 134 ° C is sent to rectification. Take the reaction liquid in the autoclave to detect, the content of 3-Dimethylaminopropylamine is 99.4 %, the residual content of propionitrile is 0.01%, the impurity content of light components is 0.15%, the content of impurities in heavy components is 0.61%, and the secondary amine is 0.37%.