Step 1. Obtain a mixture of acrylonitrile and dimethylamine at a molar ratio of 1:1-3, and vaporize the mixture at 100-120°C to obtain a primary vaporized mixture;
Step 2, make the primary vaporized mixture undergo amination reaction under the action of a portion of activated carrier, the reaction temperature is 100-120°C, the reaction pressure is 0.3-0.5MPa, and the volume space velocity of acrylonitrile is 0.1-0.25h-1, obtain a catalytic mixture;
Step 3, making the primary catalytic mixture vaporize at a high temperature under the condition of 150-180° C. to obtain the secondary vaporization mixture;
Step 4, let the secondary vaporized mixture undergo 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. Lower the temperature of the secondary catalyst to 40° C., and collect the liquid phase, which is specifically DMAPA.
A method for preparing DMAPA, said method comprising the steps of:
a) Add acrylonitrile into the synthesis kettle, control the temperature at 120°C, add dimethylamine under the conditions of stirring and cooling water circulation, and remove dimethylamine through vacuum distillation at a pressure of 0.03MPa to obtain N,N-di Methylaminoacrylonitrile; the molar ratio of acrylonitrile to dimethylamine is 1:1;
b) Add the N,N-dimethylaminoacrylonitrile prepared in step a) into the autoclave, add a hydrogenation catalyst, feed liquid ammonia into the autoclave, raise the temperature to 80°C, keep the pressure at 2.5 MPa, and feed hydrogen , stirring while maintaining the temperature at 80°C, reacting, initial distillation after sedimentation, rectification to obtain DMAPA, and then storage tank packaging; the mol ratio of hydrogenation catalyst to N,N-dimethylpropionitrile is 10:1; The fraction with a temperature higher than 134°C is sent to rectification. The reaction liquid in the autoclave is taken for testing, and the content of N,N-dimethyl-1,3-diaminopropane is 99.4%, the residual content of propionitrile is 0.01%, and the content of light components impurities 0.15%, heavy component impurity content 0.61%, including secondary amine 0.37%.