MoVTeNb Catalyst Synthesis via Hydrothermal M1 Phase Control
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Solution Overview
Problem
Current methods for producing MoVNbTe mixed oxide catalysts face challenges in achieving high purity of the M1 phase, which is essential for optimal activity and selectivity in oxidative dehydrogenation reactions.
Innovation Solution
A hydrothermal synthesis process is employed using molybdenum trioxide, vanadium pentoxide, niobium pentoxide, and tellurium dioxide as starting materials, in the presence of chelating oxo ligands like citric acid and ethylene glycol, to produce a MoVTeNb mixed oxide with a high content of the M1 phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hydrothermal synthesis methods are used with telluric acid, then the M1 phase content can be improved, but the manufacturing cost and safety risks increase significantly
Solution Approach 1:
The patent replaces expensive and hazardous telluric acid with cheap, safe, and readily available tellurium dioxide. This substitution maintains the effectiveness of the synthesis while dramatically reducing cost and safety risks. The tellurium dioxide serves as a disposable starting material that achieves the same phase formation without the drawbacks of telluric acid.
Solution Approach 2:
The patent converts the previously harmful aspect of using tellurium compounds (the hazard and cost of telluric acid) into a benefit by using tellurium dioxide, which is inherently safer and cheaper. The synthesis method transforms a hazardous process into a safe one while maintaining or improving the M1 phase purity through optimized hydrothermal conditions.
2Manufacturing precision
If attempts are made to separate M2 phase from phase mixture, then M1 phase purity can be improved, but the manufacturing complexity and time increase
Solution Approach 1:
The patent applies preliminary action by optimizing the synthesis conditions from the start to directly produce high-purity M1 phase without requiring subsequent separation steps. By carefully controlling the hydrothermal synthesis parameters (temperature, time, composition ratios, and use of chelating agents), the M2 phase formation is minimized or prevented altogether, eliminating the need for complex separation processes.
Solution Approach 2:
The patent uses parameter changes to achieve phase purity control. By adjusting synthesis parameters such as temperature (100-300°C), time (1-48 hours), and composition ratios (Mo:V:Nb:Te = 1:0.01-0.5:0.01-0.5:0.01-0.5), along with adding chelating agents like citric acid or ethylene glycol, the process selectively promotes M1 phase formation while suppressing M2 phase, achieving high purity without separation steps.
3Productivity
If higher vanadium content is used in M1 phase, then catalytic activity can be improved, but phase stability and selectivity may deteriorate
Solution Approach 1:
The patent uses parameter changes to optimize the vanadium content within the M1 phase. By controlling the V:Mo ratio and other composition parameters during synthesis, the process achieves the optimal balance between catalytic activity (enhanced by higher vanadium) and phase stability (maintained by controlled composition). The chelating agents and hydrothermal conditions help stabilize the desired phase composition.
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
The process results in a MoVTeNb mixed oxide catalyst with improved activity and selectivity for the oxidation of ethane to ethylene, achieving higher yields and maintaining phase purity.
Implementation Method 1
A hydrothermal synthesis process is employed using molybdenum trioxide, vanadium pentoxide, niobium pentoxide, and tellurium dioxide as starting materials
Implementation Method 2
in the presence of chelating oxo ligands like citric acid and ethylene glycol
Implementation Method 3
MoVNbTe mixed oxides for the oxidation of propane to acrylic acid or for the oxidative dehydrogenation of ethane to ethylene are state-of-the-art
Data Source
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AI summary
The invention relates to a method for producing a mixed oxide material, comprising the steps of: a) producing a mixture of starting compounds containing molybdenum, vanadium, niobium and tellurium-containing starting compounds as well as two chelating oxoligands, b) hydrothermally treating the mixture of starting compounds at a temperature of 100 °C to 300 °C to obtain a product suspension, c) separating and drying the solid which is contained in the product suspension resulting from step b), d) activating the solid obtained in step c) in inert gas. The invention also relates to a mixed oxide material for the oxidation of ethane, comprising the elements molybdenum, vanadium, niobium and tellurium, having the following stoichiometry: Mo1VaNbbTecOx with 0.27 < a < 0.31; 0.08 < b < 0.12; 0.08 < c < 0.12, which, when using the Cu-Kα radiation, has in the XRD spectrum diffraction reflections h, i, k and l, whose apex points are approximately at the diffraction angles (2•) 26.2° ± 0.5° (h), 27.0° ± 0.5° (i), 7.8° ± 0.5° (k) and 28.0° ± 0.5° (l), which can be produced according to the inventive method.