Influence of Al2O3 support on the thermal decomposition of ammonium metavanadate

Surface properties and catalytic behavior of MoO3/SiO2 in esterification of acetic acid with ethanol

“…The following conclusions can be drawn from the TG, DTG and DSC analyses of AHM supported on silica: The DSC curves of the samples containing low ratios of AHM (<10 wt%) on silica did not show any peaks corresponding to the decomposition of AHM, whereas the TG curves show a one‐step weight loss. These results clearly indicate that the presence of the support decreases the energy change of the decomposed material12 via the contact surface between the intermediate compounds and the support, which results in the decomposition being favored energetically at the expense of the decomposition of the intermediate compounds. Moreover, it can be suggested that the support, which has a high surface area, may strongly affect the heat change that accompanies the thermal decomposition of AHM supported on silica. On increasing the Mo loading above 10 wt% AHM, two small endothermic peaks appeared in the DSC curves which reflect that the decomposition of AHM on heating up to 400 °C occurred only in two steps. The presence of the silica support enhances the decomposition of AHM at lower temperatures; this enhancement decreases on increasing the content of AHM. …”

“…The DSC curves of the samples containing low ratios of AHM (<10 wt%) on silica did not show any peaks corresponding to the decomposition of AHM, whereas the TG curves show a one‐step weight loss. These results clearly indicate that the presence of the support decreases the energy change of the decomposed material12 via the contact surface between the intermediate compounds and the support, which results in the decomposition being favored energetically at the expense of the decomposition of the intermediate compounds. Moreover, it can be suggested that the support, which has a high surface area, may strongly affect the heat change that accompanies the thermal decomposition of AHM supported on silica.…”

“…Thus, the simultaneous and consecutive increase in the bands assigned at 990, 860, and 600 cm −1 may be due to the decomposition of MoOSi bonds and the formation of MoO 3 . These assigned bands correspond to the stretching vibration of terminal ModbondO and the asymmetric and symmetric stretching of MoOMo respectively 12…”

Catalytic decomposition of ethanol on �V2O5/AlPO4 catalysts

“…The third stage which was followed by a 6.3% weight loss corresponds to the decomposition of AHV to produce V 2 O 5 . 15 Curves b± g represent the TG and DTG curves of different ratios of AMV supported on AP. The analysis of the data of the thermal behavior of different solids indicates some trends, and the following conclusions may be drawn.…”

“…Moreover, V 2 O 5 exhibited a band at 1020 cm À1 which is assignable to the V=O stretching vibration. 15 The band at 840 cm À1 was attributed to a combination band of VÐOÐV stretching and lattice vibrations. Figure 6 shows the spectra of AMV supported on AP calcined at 600°C.…”