Vanadium Catalyst for Halogenated Nitrile Ammoxidation
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Solution Overview
Problem
Existing catalysts for the production of halogenated aromatic nitriles in fluidized-bed reactors exhibit low ammoxidation activity and selectivity, particularly for halogenated aromatic hydrocarbons, and often require hazardous chemicals like bromoethane to achieve high reaction conversion and selectivity.
Innovation Solution
A catalyst comprising a complex active component with a composition of VP a Cr b A c M d O x, where A is an alkali or alkaline earth metal, M is a specific element, and the support is silica or molecular sieves, optimized to provide high activity and selectivity without the need for bromoethane, with specific XRD peak ratios indicating improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature is raised or the V content in the catalyst is increased to increase activity, then the ammoxidation activity improves, but the selectivity of the catalyst is significantly reduced
Solution Approach 1:
The patent modifies the chemical composition parameters of the catalyst by incorporating specific elements (Fe, Co, Ni, Mn, Zn, or Al) in controlled amounts (0.1-1.0 atomic ratio relative to V), which changes the electronic and geometric properties of the active sites. This allows achieving high activity without excessive temperature or vanadium content, thereby maintaining selectivity.
Solution Approach 2:
The patent creates a composite catalyst system combining vanadium oxide with other metal oxides (Fe, Co, Ni, Mn, Zn, or Al) on a silica support. This composite structure synergistically enhances the catalytic activity through improved oxygen mobility and active site distribution, while the support structure maintains selectivity by providing appropriate pore geometry and surface properties.
2Productivity
If conventional V-Cr based oxide catalysts with multiple components are used, then halogenated aromatic nitriles can be produced, but the catalytic activity for ammoxidation of halogenated aromatic hydrocarbons is low
Solution Approach 1:
The patent removes chromium from the catalyst composition, extracting the harmful element while maintaining catalytic functionality. The simplified V-based system without Cr achieves comparable or superior activity, and eliminates the need for complex multi-component formulations, reducing both environmental harm and compositional complexity.
Solution Approach 2:
The patent changes the catalyst composition by eliminating Cr and using alternative promoters (Fe, Co, Ni, Mn, Zn, or Al) in optimized amounts. This parameter modification simplifies the catalyst system while enhancing activity through improved stability and oxygen transfer properties of the vanadium-based active phase.
3Manufacturing precision
If existing catalysts are used for halogenated aromatic nitriles production, then some conversion can be achieved, but hazardous chemicals like bromoethane are required to achieve high reaction conversion and selectivity
Solution Approach 1:
The patent enables the catalyst system to achieve high selectivity and conversion through its intrinsic properties (optimized V-based composition with Fe/Co/Ni/Mn/Zn/Al promoters and silica support structure) without requiring external hazardous promoters like bromoethane. The catalyst self-regulates the reaction pathway to favor nitrile formation through improved active site distribution and oxygen mobility.
4Productivity
If V-Cr based oxide catalysts with multiple components are used, then halogenated aromatic nitriles can be produced, but the selectivity of aromatic nitriles is low
Solution Approach 1:
The patent optimizes the compositional parameters by controlling the atomic ratio of promoter elements to vanadium (0.1-1.0) and using silica-based supports with specific surface properties. These parameter changes create optimal active site ensembles that enhance selectivity toward nitrile products while maintaining high conversion through improved oxygen mobility and stability.
Solution Approach 2:
The patent develops a composite catalyst combining vanadium oxide with Fe/Co/Ni/Mn/Zn/Al promoters on silica support. This composite structure provides synergistic effects where the promoter elements modify the electronic properties of vanadium sites to enhance selectivity, while the silica support provides structural stability and appropriate pore geometry for high conversion efficiency.
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 catalyst demonstrates enhanced ammoxidation activity and selectivity for halogenated aromatic nitriles, offering improved industrial applicability and environmental sustainability by maintaining high selectivity while reducing chromium content and eliminating the use of hazardous chemicals.
Implementation Method 1
A catalyst comprising a complex active component with a composition of VP a Cr b A c M d O x, where A is an alkali or alkaline earth metal, M is a specific element, and the support is silica or molecular sieves, optimized to provide high activity and selectivity
Implementation Method 2
with specific XRD peak ratios indicating improved performance
Data Source
Figure 1
Figure 2
AI summary
Disclosed is a fluidized-bed catalyst suitable for the production of halogenated aromatic nitriles, its preparation and application thereof. The catalyst comprises an active component and a support, wherein the active component is a complex having the following composition expressed in atomic ratio: VPaCrbAcMdOx, wherein A represents at least one metal selected from the group consisting of alkali metals and alkaline earth metals; M represents at least one element selected from the group consisting of Ti, Zr, Hf, La, Ce, Nb, Mo, W, Co, Zn, Fe, Ni, B, Sb, Bi, As, Ga, Ge, Sn, and In; in the XRD spectrum of the catalyst, diffraction peaks are present at 2θ = 27.8 ± 0.5° and 2θ = 13.8 ± 0.5°, and the ratio of the height (I1) of the diffraction peak at 2θ = 27.8 ± 0.5° to the height (I2) of the diffraction peak at 2θ = 13.8 ± 0.5° is 3.5-6, i.e. I1 : I2 = 3.5-6. The catalyst shows an excellent ammoxidation activity, and can provide a high reaction conversion and selectivity in the absence of the dangerous chemical of bromoethane, when used in the production of halogenated aromatic nitriles, and thus is particularly suitable for use in industrial applications.