Mesoporous mixed oxide catalyst comprising silicon

A catalyst comprising a mesoporous mixed oxide that comprises silicon and at least one metal M that is selected from the group consisting of tantalum, niobium, zirconium, and mixtures thereof, with the mass of metal M being between 0.1 and 20% of the mixed oxide mass, with said mixed oxide being a solid mixed oxide of both silicon and metal M, having M-O—Si bonds, said mixed oxide having a specific surface area of at least 600 m2/g, a pore volume of at least 1 ml/g and a mean diameter of the pores of between 4.5 and 17 nm, the specific surface area being a B.E.T. specific surface area that is determined by nitrogen adsorption in accordance with the ASTM D 3663-78 standard established from the BRUNAUER-EMMETT-TELLER method, the pore volume V corresponding to the volume that is observed for the partial pressure P/P0max of the nitrogen adsorption-desorption isotherm determined by the Barrett-Joyner-Halenda model, the diameter of the mesopores ϕ being determined by the formula 4000.V/SBET.