Vapor-phase oxidation of cyclohexane over supported Fe–Mn catalysts: in situ DRIFTS studies

Abstract

Alumina-supported Fe-Mn oxide catalysts were synthesized by the incipient wetness impregnation method. The catalysts were characterized by using various characterization techniques such as surface area, XRD, H2-TPR, and Raman spectra...

The effect of MgO and preparation techniques of the FeMnOδ/MgO–Al2O3 catalyst used for the vapor phase oxidation of cyclohexane

“…These peaks are attributed to the reduction of Mn 2 O 3 (375 °C, 478 °C) and Fe 2 O 3 (478 °C, 710 °C). 13,33,40 These peaks were attributed to the reduction of Mn 2 O 3 to Mn 3 O 4 , Mn 3 O 4 38,39 The results are consistent with the literature. 13 The total H 2 consumption by all the catalysts was measured and is shown in Table 2.…”

“…Supported Mn-Fe bimetallic catalysts have been reported to be more active in the oxidation of cyclohexane to produce cyclohexanone (K) and cyclohexanol (A). 13 The modification of alumina with magnesia is used to enhance the interaction of active metals with the support and undergoes oxidationreduction cycles. 4,14 Alumina is modified with magnesia for the dehydrogenation of propane over the catalyst Pt-Sn/ Al 2 O 3 .…”

“…[26][27][28][29][30] In the previous study, it was reported that lattice oxygen, which is responsible for the oxidation of adsorbed cyclohexane, is driven by the dispersed manganese over alumina support. 13 The dispersion of active metals is enhanced by modifying the support with the addition of magnesia. Magnesia modified alumina support enhances the dispersion of metals by reducing the metal interaction with the supports.…”

“…Magnesia modified alumina support enhances the dispersion of metals by reducing the metal interaction with the supports. 31,32 Magnesia-modified alumina-supported Mn-Fe bi-metallic catalysts have been studied by various characterization techniques such as X-ray diffraction (XRD), 13,25,[33][34][35][36][37][38] temperature program reduction (TPR), 25,35,36,39,40 TPD of NH 3 and CO 2 , 41-44 SEM, 21,41,[43][44][45] XPS, 17,19,23,[36][37][38]40 Raman spectroscopy, 37,38,[45][46][47] and in situ diffused reflectance infrared Fourier transform (DRIFT) spectroscopy. [47][48][49][50][51][52][53][54] Although the above literature reports have presented acceptable values of cyclohexane oxidation, the product selectivity has been observed to be low because of the deep oxidation of the oxygenated products.…”

“…Moreover, the detailed cyclohexane oxidation reaction with the catalytic activity over the catalyst surface, considering the in situ DRIFTS study for the development of catalyst, is very crucial and a very limited study has been reported. 13 The present study addresses the effect of magnesia addition in alumina, the method of catalyst preparation techniques affecting the percent conversion, and product selectivity for the oxidation of cyclohexane in the vapor phase at a low temperature and 1 atm pressure. The oxidation reaction was performed by considering a reactor (HVC-DRM-5) to collect the in situ DRIFTS spectra and simultaneously the reactivity data.…”