Hydroxylation catalyzed direct study prepared naphthol
|Keywords||Naphthol Direct hydroxylation Copper ferrite Copper and manganese -doped iron MCM-41 1,2 - naphthoquinone -1 - oxime copper|
CH bond on the aromatic ring directly into the hydroxyl radical is one of the issues currently challenging, mainly due to the stability of the aromatic ring, difficult activation, intermediate high activity, high selectivity is difficult to get one yuan product. Naphthol as a basic chemical raw materials, mainly the use of sulfonated - alkali fusion and isopropyl naphthalene method for industrial production. Process contamination big, long process, atomic utilization is low or operational complexity, poor security shortcomings. This reagent is a hydroxyl group with H2O2, iron, copper oxide (or load) or a complex thereof as a catalyst main component of the liquid phase reaction of naphthalene prepared by direct hydroxylation of naphthol. By comparing the activity of the catalyst more iron salts, indicating that the obtained calcined at 500 ℃ 4h copper ferrite highest reactivity. Cold processed raw iron and copper powder, based on iron hydroxide as the main catalytic center, while the high temperature treatment after the formation of copper ferrite crystals may octahedral copper as the main catalytic center, hydroxylation may form similar to Cu (3) of the intermediate transition state. Combined with TGA, XRD, FTIR, DRIFT analysis Cu0.95Mn0.05Fe 2 O 4 catalyst, indicating the presence of carbonates resulting surface hydroxylation occurred in the initial activation period; at 65 ℃, the reaction is 10h, hydrogen peroxide / naphthalene as 3-5 (molar ratio) of 10% aqueous acetonitrile as the solvent obtained in the conversion rate of 79.03% naphthalene, 17.38% selectivity naphthol. The study also showed that the presence of small amounts of water favor the surface hydroxyl radical aqueous layer by adsorption and adsorption of naphthalene, generating naphthol. Further addition of acetonitrile and hydrogen peroxide can directly generate active species, epoxidized naphthalene, and then decomposed naphthol. By comparing a variety of carriers, MCM-41 is the most suitable catalyst carrier hydroxy naphthalene. Hydrothermal synthesis of doped with iron, copper, manganese and a variety of MCM-41, are highly dispersed metal component located the molecular sieve. Wherein CuFeMn-MCM highest activity, selectivity and single doped with iron, copper, iron and copper rather, the optimal reaction conditions of 20% aqueous acetonitrile as the solvent, 65 ℃ reaction 13h, 52.49% conversion of naphthalene, naphthol selection of 32.45%. The results also showed that moisture increases, an increase of naphthalene in Zeolites, conversion rate greater than that of naphthalene selectivity. On the one hand the adsorption of naphthalene closer to the metal center, while adsorption of naphthalene play a weak carbon-hydrogen bond activation. The other surface of the metal peroxide in the surrounding atoms or groups under the influence of cationic generate tetrahedral complex or hydroxyl radical cage. Zeolite pore structure on the large volume of the reaction transition state obvious impact, demonstrated strong shape selectivity effects, improved naphthol selectivity. Activated carbon as the carrier, by the oxidation treatment and the amount of change in the water solvent, can improve the conversion of naphthalene. A variety of copper complexes of naphthalene hydroxylation results show that 1,2 - naphthoquinone -1 - oxime copper complex activity best. Mainly because it has a double naphthalene ring ligands, different configurations of the atoms of the six-membered ring structure more distorted, NO easy electron transfer between. Hydroxylation reaction in an anhydrous solvent, acetonitrile faster conversion rate, 55 ℃ reaction 4h, to obtain conversion of 52.05%, 26.56% selectivity. The water content increased, the conversion rate to promote increased but lower selectivity.