Mg–V–Al mixed oxides with mesoporous properties using layered double hydroxides as precursors: catalytic behavior for the process of ethylbenzene dehydrogenation to styrene under a carbon dioxide flow

Abstract

A new catalyst for the process of ethylbenzene dehydrogenation to styrene under a CO 2 atmosphere was obtained using vanadium-substituted layered double hydroxides as precursors. After calcination, vanadium-substituted hydrotalcite-like samples gave mixed oxides with a high surface area and strong mesoporous characteristics; the XRD analysis indicates the formation of Mg 3V 2O 8 and Mg 2Al 2O 4 in bulk while the XPS results point to the presence of a mixture of V 5+ and V 3+ ions on the surface. Catalytic tests show that the styrene yield and selectivity increase when the vanadium content of the sample increases. The higher catalytic activity is attributed to the formation of V 5+ on the surface that is promoted by the presence of CO 2 as a cofeed gas. The FTIR adsorption of pyridine shows that aluminum contributes to Lewis-type acidity of the catalyst and is important for establishing features of the catalyst deactivation process.