Method for preparing poly-alpha-alkene synthetic oil from coal-based raw materials

The invention relates to a method for preparing poly-alpha-alkene synthetic oil from coal-based raw materials. An alpha-alkene coarse product generated in the process of coal indirect liquefaction process is subjected to separation, alpha-alkene components with a boiling range of 40-275 DEG C and with a carbon number o 5-12 are obtained. Under action of catalysts, polymerization reaction is carried out under a pressure of 0.1-0.4 MPa and at a temperature of 80-140 DEG C. Poly-alpha-alkene synthetic oil is obtained after polymer refining and separation. The catalysts are complexes of AlCl3 or AlCl3 and alcohols. The polymer refining is clay refining and hydrofining. The viscosity index of the prepared PAO is comparable to a viscosity index of a PAO product prepared from import alkene, and is more than a viscosity index of a PAO product prepared from wax cracked alkene, and is more than 145. The dependence problems of preparation of alpha-alkene from petroleum resource are solved. In preparation of PAO from coa