Tungsten Bronze Catalyst for Propane Oxidative Dehydrogenation
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Solution Overview
Problem
Current catalytic systems for the oxidative dehydrogenation of propane to propene lack a satisfactory combination of activity and selectivity, with no economically viable method reported in the literature for this specific reaction.
Innovation Solution
The development of potassium salts of the dodecatungstophosphate ion partially substituted with vanadium and niobium, or mixed oxides derived from the structure of tungsten bronzes, which are synthesized through thermal decomposition of polyoxometalates salts with a Keggin structure, leading to the formation of mixed oxides with a tungsten bronze structure suitable for the ODH reaction of propane to propene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heterogeneous catalysts are used for ODH of propane, then the reaction can proceed, but the combination of activity and selectivity is unsatisfactory
Solution Approach 1:
The patent employs composite catalyst materials consisting of mixed oxides with tungsten bronze structure containing multiple metal elements (W, Mo, V, Nb) in specific ratios. This composite approach allows synergistic effects between different metals to simultaneously enhance both catalytic activity and propene selectivity, resolving the contradiction between reliable catalyst performance and high productivity.
Solution Approach 2:
The patent introduces specific metal elements (particularly V and Nb) at controlled concentrations within the tungsten bronze structure to create localized active sites with optimized properties. The non-uniform distribution of different metal elements throughout the catalyst structure enables regions with different functions: some areas promote dehydrogenation while others suppress over-oxidation, thereby achieving high selectivity alongside good activity.
2Productivity
If higher reaction temperatures are used to increase conversion, then productivity improves, but catalyst stability and selectivity deteriorate
Solution Approach 1:
The patent optimizes the chemical composition parameters of the catalyst, specifically the ratios of W:Mo:V:Nb and the oxidation states of metal elements, to create a catalyst that maintains structural integrity at elevated temperatures. The tungsten bronze structure with specific compositional parameters provides thermal stability while the presence of V and Nb in controlled amounts maintains selectivity even at high conversion conditions.
Solution Approach 2:
The multi-element mixed oxide composite with tungsten bronze structure provides inherent thermal stability through the robust crystal structure, while the specific metal combinations prevent sintering and phase transformation at high temperatures. This composite material approach enables the catalyst to maintain both stability and activity in the high-temperature range required for high productivity.
3Ease of manufacture
If the catalyst structure is simplified for ease of manufacture, then manufacturing becomes easier, but the ability to isolate active sites and maintain selectivity is reduced
Solution Approach 1:
The patent specifies precise compositional parameters (metal ratios, oxidation states) that define the active sites within the tungsten bronze structure. By controlling these parameters during synthesis, the catalyst achieves the necessary complexity for high selectivity while maintaining a systematic preparation approach that is relatively straightforward. The defined stoichiometric relationships simplify the manufacturing process compared to attempting to create amorphous or highly complex structured materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These catalysts demonstrate increased selectivity and stability at high reaction temperatures, achieving propene selectivity greater than 60% and conversion stability up to 50%, with the tungsten bronze structure facilitating the isolation of active sites and maintaining catalyst performance during the reaction.
Implementation Method 1
which upon undergoing thermal decomposition lead to the formation of mixed oxides of W, Nb and V, having structure of tungsten bronzes
Implementation Method 2
useful in the oxidative dehydrogenation reaction (ODH) of propane to propene
Data Source
AI summary
The present invention refers to catalysts that are selective for the reaction of ODH of propane to propene. Said catalysts are potassium salts of the dodecatungstophosphate ion partially substituted with vanadium and niobium, or mixed oxides of W, V, and Nb, with a tungsten bronze structure, obtained by thermal decomposition of polyoxometalate salts with a Keggin structure.