TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The catalyst has a molar ratio of Sn/Ni is 0.025-0.055, preferably 0.03-0.05. The porous support is an alumina or silica. The organometallic compound has a structure of formula (Sn(R)nH4-n). The organometallic compound of tin is tetrabutyl tin. The reducing gas is hydrogen.R = 1-4C alkyl or 1-4C aryl; andn = 1-4.Preferred Process: The step (b) is conducted at a temperature of 100-600 degrees C for a period of 1-40 hours. The step (c) is carried out in the absence of solvent. The step (d) is carried out at a temperature of 100-550 degrees C for 1-40 hours. The process of selective hydrogenation is carried out at a temperature of 20-200 degrees C under a pressure of 0.4-5 MPa, with hourly space velocity (defined as the ratio of volume flow of charge to the volume of catalyst) of 0.2-30 h-1.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The polyunsaturated hydrocarbon charge is steam cracking gas comprising polyunsaturated hydrocarbons containing at least 4C and having a final boiling point of up to 220 degrees C. The polyunsaturated hydrocarbons are diolefin compound, styrene compound or indene compound. EXAMPLE - Catalyst of nickel/alumina (LD 241, catalyst A) was used to prepare a catalyst based on nickel and tin (catalyst B). The catalyst A had nickel content of 10 wt.%, a specific surface of 70 m2/g, a total pore volume of 0.63 cm3/g and a bead diameter of 2-4 mm. Monometallic catalyst A (0.5 g) was reduced under hydrogen flow at 400 degrees C for 14 hours. The deposition of tin on the reduced catalyst A was carried out in the gas phase. Tetrabutyl tin (9 mg) was injected at room temperature under an atmosphere of hydrogen on the catalyst A previously reduced. After three hours, the temperature was raised to 450 degrees C under a stream of hydrogen at a rate of 2 degrees C/minute. The temperature was then maintained at 450 degrees C for 4 hours. Finally, the corresponding catalyst B supported on alumina and containing nickel and tin was cooled and stored in air.