Deactivation of VMgO x Catalysts by Coke in the Process of Isobutane Dehydrogenation with Carbon Dioxide

Abstract

The process of isobutane dehydrogenation in the presence or absence of carbon dioxide was carried out over VMgO x catalysts with different vanadium loading. The performed tests show that both the reaction atmosphere and physicochemical properties of the catalysts (related to vanadium content) have a great influence on the activity decrease and the carbonaceous deposit formation. Despite small ability of carbon dioxide to remove coke in the Boudouard reaction, the amounts of carbonaceous species deposited on the catalysts after the isobutane dehydrogenation under CO 2 atmosphere were even twice greater in comparison to those deposited in helium stream. Moreover, the rate of coke deposition during the dehydrogenation in the inert gas flow was only slightly dependent on the reaction time, in contrast to the process in carbon dioxide atmosphere. The results show that the coke formation on VMgO x is enhanced predominantly by surface acidity of the catalysts, which grows with the vanadium content and the presence of CO 2 in the feed.

Escaping undesired gas-phase chemistry: Microwave-driven selectivity enhancement in heterogeneous catalytic reactors

“…In the overlapping conversion zone, (from 10 to ~38% isobutane conversion) the selectivity values are consistently and significantly higher under MWH . Note that, during isobutane CODH, the absence of O 2 in the gas phase gave rise to coke formation that progressively deactivated the V/Al 2 O 3 catalyst ( 27 ). This is due to the absence of oxygen and is irrespective of the heating method used.…”

Conversion of Lower Hydrocarbons in the Presence of Carbon Dioxide: The Theoretic Analysis and Catalytic Tests over Active Carbon Supported Vanadium Oxide

“…More detailed description of the catalyst preparation and the theoretical calculation procedure is reported elsewhere [12,13]. Table 2 shows the main reactions of methane coupling (A1, B2) and dehydrogenation of light hydrocarbons (C1-I1) in the presence of carbon dioxide.…”

“…In such case, carbon dioxide reacts with hydrogen to form water and carbon monoxide, which shifts the equilibrium to produce olefins. The thermodynamic calculation of the two-step reaction model shows that the equilibrium conversion of hydrocarbon (for example: propane [14], isobutane [12] or ethylbenzene [3]) can be even several percent higher than that for the one-step dehydrogenation process.…”

Vanadium Oxide Supported on MSU-1 as a Highly Active Catalyst for Dehydrogenation of Isobutane with CO2

“…The carrier of MSU-1 was prepared at room temperature using sodium silicate as the source of silicon by the method reported before [22,23]. All the catalysts of VO x /MSU-1 were prepared by wet impregnation method.…”