Selective hydrogenation method for C5 fraction

The invention relates to a C5 fraction selective hydrogenation method, a hydrogenation material comes from crude isoprene of a cracking C5 fraction separation device, the material enters a fixed adiabatic bed or isothermal bed reactor and then is subjected to liquid-phase selective hydrogenation to remove isoprene, and the appropriate hydrogenation process conditions are as follows: the inlet temperature of the reactor is 25-100 DEG C, the reaction pressure is 0.8-2.5 MPa, the liquid volume space velocity is 0.5-2.5 h , and the reaction time is 1-2 hours. The volume ratio of hydrogen to oil is (50-180): 1. A catalyst used in the hydrogenation method at least contains Pd, Mn, Ni and Cu, an adopted carrier is a carrier with bimodal pore size distribution, the pore size of the carrier is 10-25 nm, the pore size of the carrier is 45-350 nm, and Ni and Cu are loaded and distributed in 45-350 nm macropores of the carrier in a microemulsion mode. Mn is loaded by a solution method, and palladium is loaded by a s