The invention relates to a catalyst comprising gold, palladium, and a porous support, in the form of at least one grain, wherein: the gold content of the catalyst is between 0.5 and 3 wt. % in relation to the total weight of the catalyst; the average size of the gold particles estimated by transmission electron microscopy (TEM) is between 0.5 nm and 5 nm; the gold is distributed homogeneously throughout said porous support; at least 80 wt. % of the palladium is distributed in a crust on the periphery of said porous support; and the gold/palladium molar ratio is higher than 2.