02677nas a2200253   4500008004100000022001400041245010700055210006900162260009500231300001200326490000800338520173800346653000602084653001402090653002102104653002802125653002102153653002302174653001202197100002502209700003002234700003302264856012602297       2006                        eng d  a0021-951700aSelective ortho-methylation of phenol with methanol over copper manganese mixed-oxide spinel catalysts0 aSelective orthomethylation of phenol with methanol over copper m  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcOCT  a278-2910 v2433 a<p>Methylation of phenol with methanol as an alkylating agent to produce 2,6-xylenol was investigated over copper manganese mixed oxide spinels, CuxMn3-xO4 (x = 0, 0.25, 0.5, 0.75, and 1) prepared through co-precipitation. The catalytic activity strongly depends on the composition, acid-base properties, and structural stability. Various parameters, including catalyst composition, reaction temperature, feed composition, and durability of the catalyst during methylation, were investigated. Mainly o-cresol and 2,6-xylenol, along with small amounts of mesitol, were found in the product. A high ortho-selectivity of 100%, with 2,6-xylenol selectivity of 74%, was observed over Cu0.25Mn2.75O4 at 673 K. These catalysts were investigated using various techniques, including BET surface area, XRD, DRS UV-vis, TPD of NH3 and CO2, TPR, and X-ray photoemission spectroscopy (XPS). Powder XRD of the catalysts revealed the formation of copper-manganese spinels with hausmannite (Mn3O4) tetragonal structure, for x = 0-0.5, whereas an increase in copper content (x &gt; 0.5) led to the formation of cubic Cu1.5Mn1.5O4 phase. DRS UV-vis, and FTIR further supported the changes in structural phases observed by XRD. Temperature-programmed desorption Of CO2 and NH3 showed that the catalysts have strong basicity along with weak acidity when x = 0 and 0.25. XPS and XAES analysis revealed the presence of only Cu2+ ions in fresh sample with x = 0.25, whereas for x = 1.0, both Cu1+ and Cu2+ were observed. The deactivation of the catalysts is attributed to structural changes occurring during the reaction. Catalytic activity is correlated with structure, as well as with acid-base properties. (c) 2006 Elsevier Inc. All rights reserved.</p>10a210a6-xylenol10aacidity-basicity10acopper-manganese oxides10aortho-alkylation10aphenol methylation10aSpinels1 aReddy, Satyanarayana1 aGopinath, Chinnakonda, S.1 aChilukuri, Satyanarayana, V.  uhttps://library.ncl.res.in/content/selective-ortho-methylation-phenol-methanol-over-copper-manganese-mixed-oxide-spinel-0