Showing papers on "o-Cresol published in 2005"
TL;DR: In this article, the synthesis of active pure and mixed phase TiO 2 catalysts by a TiCl 3 -urea-oxalic acid precursor method was described, and the catalysts were characterized by XRD, BET surface area measurements, pore-size analysis, TPD studies with NH 3 and CO 2 as probe molecules for acidity and basicity.
Abstract: The investigation describes synthesis of active pure and mixed phase TiO 2 catalysts by a TiCl 3 –urea–oxalic acid precursor method. Pure and mixed phase TiO 2 catalysts could be obtained by varying the concentration of oxalic acid during synthesis. A minimum of 25 mol% of oxalic acid during synthesis was found to bring about complete phase transition from rutile to anatase. The catalysts were characterized by XRD, BET surface area measurements, pore-size analysis, TPD studies with NH 3 and CO 2 as probe molecules for acidity and basicity. In situ FTIR studies using pyridine as a probe molecule for determining the type of acid sites. The various TiO 2 catalysts were evaluated for the methylation of phenol reaction. While all the samples were near100% ortho-selective, they showed a unique activity profile as the concentration of oxalic acid was increased during the synthesis. The observed yield and product selectivity is correlated with the surface properties of the catalysts. The overall catalytic activity did not show particular phase dependence. Strong Lewis acid–weak Lewis base pairs were identified as the active centers for ortho-selectivity. The catalytic activity was primarily governed by the concentration of effective strong Lewis acid–weak Lewis base pairs. The selectivity between the ortho-products o -cresol and 2,6-xylenol is greatly influenced by the pore-size distribution.
29 citations
TL;DR: In this article, the gas phase catalytic alkylation of phenol with methanol was investigated over a series of spinel-type cobalt chromite catalysts.
Abstract: The gas phase catalytic alkylation of phenol with methanol was investigated over a series of spinel-type cobalt chromite catalysts. The molar ratio of Co/Cr and the calcination temperature have considerable effect on the catalytic performance of the samples. Among them, the Co/Cr=0.8 sample calcined at 723 K shows the highest activity (97.3% phenol conversion) with a total 94.8% ortho-selectivity to o-cresol and 2,6-xylenol at the reaction temperature of 693 K.
18 citations