A silica-rich support and a catalyst containing the silica-rich support and a catalytic component. The support has a specific structure characterized by a set of claimed physicochemical properties: in the .sup.29Si MAS NMR spectrum the state of silicon is characterized by the presence of lines with chemical shifts -100.+-.3 ppm (line Q.sup.3) and -110.+-.3 ppm (line Q.sup.4), with the ratio of the integral intensities of the lines Q.sup.3/Q.sup.4 of from 0.7 to 1.2 (FIG. 1); in the IR spectrum there is an absorption band of hydroxyl groups with the wave number 3620 3650 cm.sup.-1 and half-width 65 75 cm.sup.-1 (FIG. 2); the carrier has a specific surface area, as measured by the BET techniques from the thermal desorption of argon, S.sub.AR=0.5 30 m.sup.2/g and the surface, as measured by alkali titration techniques, S.sub.Na=10 250 m.sup.2/g, with S.sub.Na/S.sub.Ar=5 30.