Preparation method of g-C3N4/MgCl2 composite carrier type propylene polymerization catalyst

The invention discloses a preparation method of a g-C3N4/MgCl2 composite carrier type propylene polymerization catalyst, which comprises the following steps of: (1) under the conditions of N2 protection and continuous stirring, adding alkyl magnesium chloride into a glass reactor filled with an organic solvent, and then stirring for 1-3 hours until the alkyl magnesium chloride is completely dissolved; (2) adding treated g-C3N4 powder into the magnesium chloride solution, and continuing to stir until the mixture is fully mixed and reacted; (3) at a relatively low temperature, dropwise adding TiCl4 into the solution obtained in the step (2), and fully mixing and reacting while stirring; and (4) adding an internal electron donor into the solution obtained in the step (3), gradually heating, reacting for a first preset time, and filtering out the liquid; and adding TiCl4 again to react for a second preset time, and finally filtering, washing and drying to obtain the g-C3N4/MgCl2 composite carrier type propylene p