Catalyst for acid-catalyzed by hydrocarbon conversions

A catalyst for acid-catalyzed hydrocarbon conversions, in particular for the alkylation of olefins with isoparaffins, comprising a crystalline faujasite of the X, Y or LSX type with an SiO2-Al2O3 molar ratio of <10, wherein alkali cations are at least partially replaced with trivalent or polyvalent cations, wherein the residual concentration of alkali cations is less than about 0.2% by weight, wherein the concentration of Bronsted acid sites, determined as a function of pyridine chemisorbed on the catalyst surface, comprises about 0.1 to 4 mmol/g of catalyst, and wherein the ratio between the concentration of the acid sites of the Bronsted type (B) and of Lewis type (L), expressed as a surface ratio of absorption bands at 1540 ±5 cm−1 (B) and 1450 ±5 cm−1 (L) after heating to a temperature of 450° C is about 1.4 or higher, wherein the portion of the pyridine not yet desorbed from the catalyst surface at a temperature of 450° C which is bonded to the Bronsted acid sites comprises about 30 to 60 wt % of the pyridine chemisorbed at the Bronsted acid sites at 100° C.