Ecofriendly liquid phase oxidation with hydrogen peroxide of 2,6-dimethylphenol to 2,6-dimethyl-1,4-benzoquinone catalyzed by TiO2?CeO2 mixed xerogels

MAGDALENA PALACIO; PAULA I. VILLABRILLE; GUSTAVO P. ROMANELLI; PATRICIA G. VÁZQUEZ; CARMEN V. CÁCERES

APPLIED CATALYSIS A-GENERAL

Elsevier

Lugar: Amsterdam; Año: 2009 vol. 359 p. 62 - 68

0926-860X

Titania-ceria mixed xerogels were prepared with 10% (w/w) CeO2 and three different pH values, 2, 3 and 4, during the sol-gel process. The gels were dried in air at 50° C for 24 h and calcined in air at 200 °C and 800 °C for 4 h. Moreover, a sample without cerium, 100% (w/w) TiO2, was prepared to be kept as reference material. The sol-gel synthesis of the latter was carried out at pH=3, with a subsequent heat treatment similar to the previous ones. The prepared solids were characterized by means of XRD, SEM, DRS, FT-IR, TEM and EDX. Their textural properties were determined by adsorption-desorption isotherms of N2 at 77 K. The xerogels were tested as catalysts in the liquid phase oxidation of 2,6-dimethylphenol at 20 °C, using ethanol as solvent and aqueous hydrogen peroxide as a clean oxidizing agent. The 2,6-dimethyl-p-benzoquinone yield achieved was of 85-96% using the mixed xerogels as catalysts, and of 49% when the catalyst of titania without cerium was used. The best performance was achieved by the mixed xerogel synthesized at pH=4 and calcined at 200 °C; 100% of conversion and 96% of yield in 2,6-dimethyl-p-benzoquinone were obtained in this case after 6 h of reaction. A mixture of ethanol-water (35:65% (v/v)) was also a good solvent to perform this reaction, a conversion of 100% and a yield of 40% were obtained in 4 h.