A process for the synthesis of a zinc dicarboxylate catalyst, comprising the steps of: (a) providing a solution of a zinc precursor having the general formula Zn(L) 2 ·nH 2 O, wherein n is comprised between 0 and 20, L is selected in the group consisting of: NO 3 , CH 3 CO 2 , (SO 4 ) 0,5 , halide, and acetyl acetonate (AcAc); (b) adding a solution of a base to said solution of a zinc precursor, thereby obtaining a precipitate; (c) separating the precipitate from the supernatant solution and subjecting the solid thus obtained to a heat treatment thereby obtaining a zinc-based compound comprising a mixture of ZnO and a compound having the general formula (I): Zn x (OH) y (L) z ·nH 2 O Formula (I) wherein L is as defined in step (a), 2 x = y + z ; wherein x is comprised between 1 and 5, y is comprised between 1 and 8, z is comprised between 1 and 2, and n is comprised between 0 and 20; wherein said heat treatment is carried out - at a temperature (T): 30 °C < T < 90 °C and for a period of time (t): 20 hours < t ≤ 60 hours; or - at a temperature (T): 90 °C ≤ T ≤ 150 °C and for a period of time (t): 20 minutes ≤ t ≤ 20 hours; or - at a temperature (T): 150 °C < T ≤ 400 °C and for a period of time (t): 20 minutes ≤ t ≤ 15 hours; (d) reacting said zinc-based compound with a saturated aliphatic dicarboxylic acid. (a) providing a solution of a zinc precursor having the general formula Zn(L) 2 ·nH 2 O, wherein n is comprised between 0 and 20, L is selected in the group consisting of: NO 3 , CH 3 CO 2 , (SO 4 ) 0,5 , halide, and acetyl acetonate (AcAc); (b) adding a solution of a base to said solution of a zinc precursor, thereby obtaining a precipitate; (c) separating the precipitate from the supernatant solution and subjecting the solid thus obtained to a heat treatment thereby obtaining a zinc-based compound comprising a mixture of ZnO and a compound having the general formula (I): Zn x (OH) y (L) z ·nH 2 O Formula (I) wherein L is as defined in step (a), 2 x = y + z ; wherein x is comprised between 1 and 5, y is comprised between 1 and 8, z is comprised between 1 and 2, and n is comprised between 0 and 20; wherein said heat treatment is carried out - at a temperature (T): 30 °C < T < 90 °C and for a period of time (t): 20 hours < t ≤ 60 hours; or - at a temperature (T): 90 °C ≤ T ≤ 150 °C and for a period of time (t): 20 minutes ≤ t ≤ 20 hours; or - at a temperature (T): 150 °C < T ≤ 400 °C and for a period of time (t): 20 minutes ≤ t ≤ 15 hours; x is comprised between 1 and 5, y is comprised between 1 and 8, z is comprised between 1 and 2, and n is comprised between 0 and 20; wherein said heat treatment is carried out - at a temperature (T): 30 °C < T < 90 °C and for a period of time (t): 20 hours < t ≤ 60 hours; or - at a temperature (T): 90 °C ≤ T ≤ 150 °C and for a period of time (t): 20 minutes ≤ t ≤ 20 hours; or - at a temperature (T): 150 °C < T ≤ 400 °C and for a period of time (t): 20 minutes ≤ t ≤ 15 hours; - at a temperature (T): 30 °C < T < 90 °C and for a period of time (t): 20 hours < t ≤ 60 hours; or - at a temperature (T): 90 °C ≤ T ≤ 150 °C and for a period of time (t): 20 minutes ≤ t ≤ 20 hours; or - at a temperature (T): 150 °C < T ≤ 400 °C and for a period of time (t): 20 minutes ≤ t ≤ 15 hours; (d) reacting said zinc-based compound with a saturated aliphatic dicarboxylic acid. <EOS>