The influence of over-stoichiometry in La2Ni0.9V0.1O4.15+δ on selective oxidative dehydrogenation of propane

Crapanzano, Salvatore; Babich, Igor V.; Lefferts, Leon

doi:10.1016/j.cattod.2012.04.041

Cited by 4 publications

(2 citation statements)

References 38 publications

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“…Pure or partially substituted (A,A′,A′′)(B,B′,B′′)(O,X) 3 perovskites have been studied in various catalytic applications, , including oxygen evolution in alkaline solution, photocatalytic applications, CO oxidation, DeNO x reactions, and total combustion of alkanes and volatile organic compounds, ,− with the aim to replace noble metals as catalytically active components. Perovskites were implemented in oxygen-permeable membranes used in membrane reactors for selective oxidation of methane and other short-chain alkanes to higher hydrocarbons and olefins. − Olefins were synthesized at high temperatures over perovskite-supported platinum catalysts in the catalytic partial oxidation of ethane applying short contact times, in catalytic dehydrogenation of propane in the presence of steam, , and in oxidative dehydrogenation of propane applying chemical looping technologies or pulse experiments to control the activation of molecular oxygen on the surface of the perovskite catalyst. , …”

Section: Introductionmentioning

confidence: 99%

“…15−17 Olefins were synthesized at high temperatures over perovskite-supported platinum catalysts in the catalytic partial oxidation of ethane applying short contact times, 18 in catalytic dehydrogenation of propane in the presence of steam, 19,20 dehydrogenation of propane applying chemical looping technologies or pulse experiments to control the activation of molecular oxygen on the surface of the perovskite catalyst. 21,22 The most productive catalysts so far in the activation of short-chain hydrocarbons under oxidative conditions are based on vanadium oxides. 23 In general, high selectivity to valueadded products in the oxidation of alkanes is achieved over the semiconductors vanadyl pyrophosphate (VO) 2 P 2 O 7 24 and MoVTeNbO x 25,26 in n-butane or propane oxidation, respectively, even at high alkane conversion.…”

Section: ■ Introductionmentioning

confidence: 99%

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Surface Conditions That Constrain Alkane Oxidation on Perovskites

et al. 2020

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The crystal structure of perovskites can incorporate a wide variety of cations, which makes this class of materials so interesting for studies of links between solid-state chemistry and catalysis. Perovskites are known as typical total combustion catalysts in hydrocarbon oxidation reactions. The fundamental question that we investigate here is whether surface modifications of perovskites can lead to the formation of valuable reaction products in alkane oxidation. We studied the effect of segregated two-dimensional surface nanostructures on selectivity to propene in the oxidative dehydrogenation of propane. Manganese-based perovskites AMnO 3 (A = La, Sm) were prepared by combustion and hydrothermal synthesis. Bulk and surface structures were investigated by X-ray diffraction, temperature-programmed reduction, aberration-corrected scanning transmission electron microscopy (STEM), multiwavelength Raman, and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) in combination with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Surface oxygen species responsible for C−H activation were distinguished by AP-XPS on the basis of a rigorous in situ analysis of the O 1s spectra recorded under a broad range of reaction conditions. Signals at 529.2, 530.1, 530.9, 531.2, and 531.8 eV were attributed to lattice O, defect-affected O, surface O, oxygen in carbonates, and hydroxyl groups, respectively. Operando AP-XPS revealed critical surface features, which occur under catalyst operation. The catalyst performance depends on the synthesis technique and the reaction conditions. In presence of a two-dimensional MnO x surface phase, addition of steam to the feed resulted in an increase in selectivity to the partial oxidation product propene to practically relevant values. The selectivity increase is related to the presence of Mn in a low oxidation state (2+/3+), an increased concentration of hydroxyl groups, and a higher abundance of adsorbed activated oxygen species on the catalyst surface. The surface analysis of a working catalyst highlights the importance of the termination layer of polycrystalline perovskites as a genuine property implemented by catalyst preparation. Such a termination layer controls the chemical properties and reactivity of perovskites. The information provides input for the development of realistic models that can be used by theory to predict functional properties.

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