Mixed Oxide Supported MoO3 Catalyst: Preparation, Characterization and Activities in Nitration of o-xylene

Abstract

TiO2-ZrO2 mixed oxide support was prepared and impregnated with 12 wt % MoO3 and calcined at various temperatures. The resultant catalyst systems were characterized by XRD, FT-IR, BET, SEM, NH3-TPD and pyridine adsorbed FT-IR methods to know the physico-chemical changes occurred in course of thermal treatment. Activities of these catalysts were tested by employing them in the nitration of o-xylene. Mostly, 500 oC calcined catalyst sample was found to be most active for nitration reaction. Catalyst calcined at higher temperatures showed the negative influence on o-xylene conversion and 4-nitro-o-xylene selectivity. Conversion can be correlated with the presence of strong Brönsted acid sites over the catalyst surface whereas change in selectivity was found attributed to the pore diameter of the catalyst. These catalysts also performed satisfactorily, when used for nitration of other aromatics. No use of corrosive sulfuric acid and efficient reusability of the catalyst make the process environmentally friendly and economic. © 2010 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Various Characteristics of Nanosized V2O5/TiO2and MoO3–Modified V2O5/TiO2Catalytic Systems Used in Redox-Initiated Polymerization of Methyl Methacrylate

“…low concentrations of the supported oxides [28]. Absence of characteristic peaks of molybdena may confirm that MoO 3 up to $10 wt% remains on the titania surface as an X-ray amorphous phase or in a highly dispersed state [29]. Similar results were obtained for the 6Mo-8 V=T (coat 1) and 8 V-6Mo= T (coat 2) samples.…”

“…Increasing Mo ratio to 6 wt%, the band at 1020 cm À1 disappeared, while the stretching modes of monolayered amorphous VO x species and=or polymeric VO 4 units (of n(V = O), [8,11]), with decreased sizes, were shown shifting to 972 cm À1 . The appearance of a new shoulder at $875 cm À1 , assigned mostly to antisymmetric vibration of Mo-O-Mo or O-Mo-O, reflected the possible interaction of MoO 3 with titania support [29]. For evidence, with a higher ratio of Mo, namely 9 wt%, two clear bands could be observed, at 987 and 893 cm À1 , linked with weakened V=O bond of modified strengths [30], as a result of the mentioned interaction.…”

How TiO2facets determine arsenic adsorption and photooxidation: spectroscopic and DFT studies

“…2b). 35 In contrast, the other two NPs exhibited a homogenous distribution of weaker acid sites on the surface. The distribution of acid sites is closely related to surface atomic coordination and arrangement, indicating that different crystal facets may endow the same Lewis acid sites with different strengths.…”

Photocatalytic degradation of Rhodamine B dye by cotton textile coated with SiO2-TiO2 and SiO2-TiO2-HY composites

“…This spectrum also exhibits a weak band at 936 cm À1 related to SiÀ ÀOÀ ÀTi bonds, but this band was not detected in any SiO 2 -TiO 2 -HY composites, because probably it is overlapped by the intense bands of the zeolite structure. The strong bands assigned to the HY zeolite are present in all FTIR spectra of SiO 2 -TiO 2 -HY composites, namely: 461, 575, 723, 791, 1033, 1633 and 3433 cm À1 are identified in [46], except the first one that corresponds to bending modes of SiÀ ÀOÀ ÀSi linkage [47]. Only for the STH-750 composite, the bands at 791 and 723 cm À1 disappeared and new bands appeared at 784 and 671 cm À1 , which can be attributed to TiO 2 anatase phase [47] and TiÀ ÀO [17], respectively.…”

“…The strong bands assigned to the HY zeolite are present in all FTIR spectra of SiO 2 -TiO 2 -HY composites, namely: 461, 575, 723, 791, 1033, 1633 and 3433 cm À1 are identified in [46], except the first one that corresponds to bending modes of SiÀ ÀOÀ ÀSi linkage [47]. Only for the STH-750 composite, the bands at 791 and 723 cm À1 disappeared and new bands appeared at 784 and 671 cm À1 , which can be attributed to TiO 2 anatase phase [47] and TiÀ ÀO [17], respectively. On the other hand, the band that appears at 2924 cm À1 confirms the existence of À ÀOH terminal [36], indicating the formation of acid groups during the gel formation, which eventually can be de-protonate [48] favouring the adsorption of RhB molecules or forming free radicals.…”