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Cerium containing mixed oxides derived from hydrotalcites was prepared and its catalytic activity was studied for oxidative dehydrogenation of ethyl benzene to styrene. Structural, spectroscopic and morphological features of the catalyst have been thoroughly examined with various physico-chemical characterization methods. Raman spectroscopy studies show evidence for oxygen vacancies in lower loadings of cerium which enhanced the oxygen migration. The transmission electron microscopy image showed good dispersion of ceria clusters on the mixed metal oxide. The catalytic activity results suggested that the conversion of ethyl benzene and styrene yield is stable for at least 12 hours without any significant catalyst deactivation. The styrene selectivity and ethyl benzene conversion were higher in a catalyst containing 0.03 mole percentage of cerium. Structural features of the spent catalysts have also been examined to demonstrate the stability of the catalyst during the reaction. † Electronic supplementary information (ESI) available. See

Styrene (ST) is an industrially important commodity chemical, and design of a suitable catalyst, which provides high ethyl benzene (EB) conversion and styrene selectivity at lower temperature with sustainable activity, is one of the major challenges in the field of heterogeneous catalysis. Manganese incorporated in titania (Mn x Ti 1Àx O 2 ) anatase lattice, prepared via the solution combustion method, was evaluated for oxidative dehydrogenation (ODH) of EB with O 2 or air. Mn x Ti 1Àx O 2 catalysts were characterized by different physiochemical methods. Up to 15% Mn could be introduced into the TiO 2 lattice. TEM and XRD indicate disordered mesoporosity, further confirmed by adsorption isotherm analysis. Mn x Ti 1Àx O 2 catalysts were evaluated for ST synthesis from EB using air or oxygen as oxidant between 440 and 570 C. Reaction conditions have been varied systematically, such as catalyst composition, and EB/air/O 2 flow. Mn x Ti 1Àx O 2 shows sustainable 55% styrene yield for 45 h without deactivation under optimum conditions. A thorough analysis of spent catalysts demonstrates the conversion of initial anatase phase Mn x Ti 1Àx O 2 to Mn 3 O 4 supported on the rutile (R) phase of TiO 2 . The above change occurs in the first few hours of reaction and the Mn 3 O 4 on R-TiO 2 phase is the active phase of the catalyst and responsible for sustainable activity for longer duration.

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