A mixed oxide, having the general formula: X a Y b Z c O d. pC wherein X is selected from Ni, Co and mixtures thereof, Y is selected from Mo, W and mixtures thereof, Z is selected from Si, Al and mixtures thereof, O is oxygen C is selected from: - a nitrogenated compound N, - an organic residue deriving from the partial calcination of the nitrogenated compound N, wherein said nitrogenated compound is selected from: a) an alkyl ammonium hydroxide corresponding to the formula: R I R II R III R IV NOH wherein the groups R I, R II, R III and R IV, the same or different, are aliphatic groups containing from 1 to 7 carbon atoms, b) an amine having formula: R 1 R 2 R 3 N wherein R 1 is a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms and R 2 and R 3, the same or different, are selected from H and a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms, said alkyl being equal to or different from R 1, a, b, c, d are the number of moles of the elements X, Y, Z, O, respectively, p is the weight percentage of C with respect to the total weight of the compound having formula a, b, c, d are higher than 0 a/b is higher than or equal to 0.3 and lower than or equal to 2, (a+b)/c is higher than or equal to 0.8 and lower than or equal to 10, d = (2a+6b+Hc)/2 wherein H = 4 when Z = Si H = 3 when Z = Al and p is higher than 0 and lower than or equal to 40%. wherein X is selected from Ni, Co and mixtures thereof, Y is selected from Mo, W and mixtures thereof, Z is selected from Si, Al and mixtures thereof, O is oxygen C is selected from: - a nitrogenated compound N, - an organic residue deriving from the partial calcination of the nitrogenated compound N, wherein said nitrogenated compound is selected from: a) an alkyl ammonium hydroxide corresponding to the formula: R I R II R III R IV NOH wherein the groups R I, R II, R III and R IV, the same or different, are aliphatic groups containing from 1 to 7 carbon atoms, b) an amine having formula: R 1 R 2 R 3 N wherein R 1 is a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms and R 2 and R 3, the same or different, are selected from H and a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms, said alkyl being equal to or different from R 1, a, b, c, d are the number of moles of the elements X, Y, Z, O, respectively, p is the weight percentage of C with respect to the total weight of the compound having formula a, b, c, d are higher than 0 a/b is higher than or equal to 0.3 and lower than or equal to 2, (a+b)/c is higher than or equal to 0.8 and lower than or equal to 10, d = (2a+6b+Hc)/2 wherein H = 4 when Z = Si H = 3 when Z = Al and p is higher than 0 and lower than or equal to 40%. - a nitrogenated compound N, - an organic residue deriving from the partial calcination of the nitrogenated compound N, wherein said nitrogenated compound is selected from: a) an alkyl ammonium hydroxide corresponding to the formula: R I R II R III R IV NOH wherein the groups R I, R II, R III and R IV, the same or different, are aliphatic groups containing from 1 to 7 carbon atoms, b) an amine having formula: R 1 R 2 R 3 N wherein R 1 is a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms and R 2 and R 3, the same or different, are selected from H and a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms, said alkyl being equal to or different from R 1, a, b, c, d are the number of moles of the elements X, Y, Z, O, respectively, p is the weight percentage of C with respect to the total weight of the compound having formula a, b, c, d are higher than 0 a/b is higher than or equal to 0.3 and lower than or equal to 2, (a+b)/c is higher than or equal to 0.8 and lower than or equal to 10, d = (2a+6b+Hc)/2 wherein H = 4 when Z = Si H = 3 when Z = Al and p is higher than 0 and lower than or equal to 40%. a) an alkyl ammonium hydroxide corresponding to the formula: R I R II R III R IV NOH wherein the groups R I, R II, R III and R IV, the same or different, are aliphatic groups containing from 1 to 7 carbon atoms, b) an amine having formula: R 1 R 2 R 3 N wherein R 1 is a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms and R 2 and R 3, the same or different, are selected from H and a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms, said alkyl being equal to or different from R 1, a, b, c, d are the number of moles of the elements X, Y, Z, O, respectively, p is the weight percentage of C with respect to the total weight of the compound having formula a, b, c, d are higher than 0 a/b is higher than or equal to 0.3 and lower than or equal to 2, (a+b)/c is higher than or equal to 0.8 and lower than or equal to 10, d = (2a+6b+Hc)/2 wherein H = 4 when Z = Si H = 3 when Z = Al and p is higher than 0 and lower than or equal to 40%. R 1 is a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms and R 2 and R 3, the same or different, are selected from H and a linear, branched or cyclic alkyl, containing from 4 to 12 carbon atoms, said alkyl being equal to or different from R 1, a, b, c, d are the number of moles of the elements X, Y, Z, O, respectively, p is the weight percentage of C with respect to the total weight of the compound having formula a, b, c, d are higher than 0 a/b is higher than or equal to 0.3 and lower than or equal to 2, (a+b)/c is higher than or equal to 0.8 and lower than or equal to 10, d = (2a+6b+Hc)/2 wherein H = 4 when Z = Si H = 3 when Z = Al and p is higher than 0 and lower than or equal to 40%.