An analysis of the first steps of phenol adsorption-oxidation over coprecipitated Mn?Ce catalysts: a DRIFTS study

D´ALESSANDRO ORIANA; HORACIO THOMAS; JORGE SAMBETH

REACTION KINETICS AND CATALYSIS LETTERS

SPRINGER

Lugar: Budapest; Año: 2012 vol. 102 p. 295 - 309

0133-1736

Abstract A series of Mn?Ce(M) solids (M = K or Na), with molar ratios 100?0,50?50 and 0?100 were prepared by co-precipitation of manganese and ceriumnitrate from NaOH or KOH solutions at pH = 11. In addition, part of the solidsprecipitated with NaOH were dried and impregnated with a Cu2? salt. The solidswere characterized by XRD, Specific Surface Area, XPS and EDS. The characterizationanalyses show the formation of Mn mixed oxides with different oxidationstates (Mn3?, Mn4?), for samples without Ce or Mn?Ce(M) 50?50. In the lattersolid and in the one where there is no Mn, the formation of CeO2 (fluorite type) wasdetected. The samples were tested in the phenol removal in water at 100 C and atatmospheric pressure with the aim to analyze the adsorbed species in the first stageof the adsorption-oxidation mechanisms. The results indicate, on the one hand, that[MnOx] is the active species in the process and that the most active solids are thosethat present (i) a higher concentration of OI, (ii) a higher amount of Mn4? ions.DRIFT spectroscopy showed a possible mechanism of phenol adsorption on twosites, in the first one by H interaction of OH (phenol) with an OH of the catalyst andin the second, by the formation of a phenolate species between an O (OH phenol)and Mnn?.