Reoxidation of modified manganese and magnesium oxides by carbon dioxide

Activity of vanadium magnesium oxide supported catalysts in the dehydrogenation of isobutane

“…The first one is a direct process, shown in the equation 3, where the CO 2 promotes the dehydrogenation through reoxidizing the catalyst surface, reduced by isobutane. This one-step pathway is in agreement with the Mars and van Krevelen mechanism [11,12]. The second one, known as a two-step pathway, is a simple dehydrogenation (equation 1) followed by the reverse water gas shift reaction (RWGS, equation 4):…”

“…In the presence of an oxidizing agent (CO 2 ) the lattice oxygen becomes available for the Mars and van Krevelen reaction mechanism [11,12], but it is known from the literature that the reversibility of the reaction (6) is very low [22]. Therefore, most of carbon oxide produced during the dehydrogenation in CO 2 atmosphere comes from the reverse water gas shift reaction (4) and the gasification of coke (5).…”

“…Recently, several attempts were made to use carbon dioxide as an unconventional source of oxygen in the oxidative dehydrogenation of isobutane [9][10][11][12][13][14][15][16]. The overall reaction can be described as follow (3):…”

“…Many results indicate that isobutene is formed by both presented mechanisms [11,12]. Moreover, in the dehydrogenation process carbon dioxide can act as a diluent, it delivers the required heat and reduces coking of catalyst by the coke gasification [10][11][12][13][14][15]:…”

Dehydrogenation of isobutane with carbon dioxide over a vanadium-magnesium oxide catalyst

“…According to the literature [1][2][3][4][5][6][7][8] it is known that there are two possible pathways of the dehydrogenation of hydrocarbons with carbon dioxide, depending on both the catalyst and the reaction conditions. The first of them is a direct process, where equilibrium reaction (1) requires the existence of redox and/or _________________________ acid-base pairs on the catalyst surface [1][2][3][4][5][6][7][8].…”