Abstract: A nickel cermet containing a metal nickel phase and an yttria stabilized zirconia phase, is prepared by a process comprising: preparing a suspension of the zirconia in demineralized water; preparing a solution of a nickel salt in demineralized water; mixing the nickel solution and the zirconia dispersion; eliminating the water from the mixture to obtain a solid containing particles of the zirconia covered with the nickel salt; calcining the solid under oxidizing conditions to form particles of the zirconia covered with nickel oxide; and reducing the nickel oxide with hydrogen to nickel metal.

Abstract: Olefins with between 4 and 24 and preferably between 10 and 20 carbon atoms are selectively dimerized by using zeolite catalysts in acid form which are partially exchanged with salts of metals having a valency of two or more.