Isotope Studies in Oxidation of Propane over Vanadium Oxide

Abstract

The oxidation of propane has been studied over silica-supported vanadium oxide and polycrystalline, bulk MoVTeNb oxide with M1 structure. Temperature-programmed reaction experiments were performed, and the reactivity of propane molecules labeled with deuterium and 13C, respectively, was analyzed under steady-state conditions. The measurement of kinetic isotope effects reveals fundamental differences in the activation of propane over the two catalysts. The reaction network of consecutive and parallel reactions of the formed propylene is comparable. However, oxygen insertion into the CHO group of acrolein under formation of acrylic acid is faster over M1 than oxidation at the CH2 group and decarbonylation to acetaldehyde. In contrast, the latter process is preferred over silica-supported vanadium oxide resulting in lower selectivity to unsaturated oxygenates

Constructing A Rational Kinetic Model of the Selective Propane Oxidation Over A Mixed Metal Oxide Catalyst

“…The measurement of kinetic isotope effects (KIE) in propane oxidation revealed essential differences in the activation of the propane molecule over MoVTeNb oxide with M1 structure and silica-supported vanadium oxide. Whereas the abstraction of the first hydrogen atom at the methylene group of the C 3 H 8 molecule is rate limiting over silica-supported vanadium oxide, activation of propane over M1 clearly involves both methyl and methylene groups simultaneously in rate-limiting process(es) [51]. The formation pathways of carbon oxides during propane oxidation were studied by means of pulse experiments with 13 C-labeled/unlabeled propane/oxygen mixtures.…”

Learning Design Rules for Selective Oxidation Catalysts from High-Throughput Experimentation and Artificial Intelligence

“…The selective partial oxidation of light alkanes to value-added olefins or oxygenates is an efficient route for feedstock upgrading. 10 However, the intricate surface reaction networks 11 typically lead to product mixtures containing up to 20 different molecules, including undesirable byproducts such as CO and CO 2 . In order to selectively produce the olefins or the oxygenates, mixed-metal oxide or phosphate heterogeneous catalysts based on molybdenum and vanadium redox-active species have been used, such as MoVTeNbO x and the state of the art industrial catalyst for n -butane selective oxidation, vanadyl pyrophosphate.…”

Towards Experimental Handbooks in Catalysis

“…As for production of basic chemicals and consumer products in the chemical industry, high selectivity to the desired reaction product allows for the efficient utilization of raw materials, the minimization of energy consumption by avoiding separation and purification steps, and the mitigation of waste formation or emission of greenhouse gases such as CO 2 . However, development of selective catalysts for reactions with numerous products, including selective oxidation of hydrocarbons [3][4][5][6][7][8], and synthesis of olefins and oxygenates via hydrogenation of carbon oxides [9][10][11], are challenging due to their underlying complex organic reaction networks.…”

“…Kinetic data must be linked to all metadata including the workflow of the entire experiment; Catalyst performance data must be documented together with the metadata completely and in a standardized form. 4. Catalysts need to be tested using a broad field of process parameters including temperature, pressure, contact time, and various feed compositions following standardized procedures since the optimal operation conditions depend very much on the catalyst and might vary significantly for various catalysts applied in the same reaction.…”

“…Reaction networks of propane oxidation over Mo-V-based mixed metal oxide catalysts reprinted from[4] with permission of Wiley VCH. The reaction intermediates and products colored in blue were detected in the effluent gas stream by gas chromatography over a catalyst working in steady state1 3 …”