MoBiFe Catalyst Ammoxidation Selectivity
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Solution Overview
Problem
The production of acrylonitrile and hydrogen cyanide requires excessive amounts of ammonia, increasing costs due to inefficient ammonia conversion in ammoxidation reactions.
Innovation Solution
A catalyst comprising Mo, Bi, and Fe with specific peak intensity ratios in X-ray diffraction analysis, along with additional elements and a production method involving spray-drying and calcination in the presence of oxygen and ammonia, is used to enhance ammonia conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If excessive ammonia is used in the ammoxidation reaction, then the productivity of acrylonitrile and hydrogen cyanide increases, but the production cost increases due to inefficient ammonia conversion
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by incorporating specific ratios of Mo, Bi, and Fe oxides, along with optional additional elements (X, Y, Z), to optimize ammonia conversion efficiency. The catalyst composition is represented by formula (1) with specific atomic ratio ranges that maximize the utilization of ammonia in the ammoxidation reaction, thereby improving productivity while reducing ammonia loss.
Solution Approach 2:
The patent employs a composite oxide catalyst system combining multiple metal oxides (MoO3, Bi2O3, Fe2O3) in specific ratios. This composite material approach creates synergistic effects among the different metal oxides, enhancing the catalyst's ability to efficiently convert ammonia while maintaining high productivity for acrylonitrile and hydrogen cyanide production.
2Loss of substance
If a catalyst with high ammonia conversion efficiency is developed, then the cost of production decreases, but the catalyst composition and structure become more complex
Solution Approach 1:
The patent establishes specific parameter ranges for the catalyst composition (atomic ratios of Mo, Bi, Fe and optional elements) and crystal structure (peak intensity ratios in XRD analysis). By optimizing these parameters within defined ranges, the patent achieves high ammonia conversion efficiency while maintaining manageable catalyst complexity through systematic composition control.
Solution Approach 2:
The patent employs a preliminary action principle in the catalyst preparation process through spray-drying of slurry followed by calcination. This pre-treatment approach creates a catalyst with the desired composition and crystal structure before use, ensuring high ammonia conversion efficiency while simplifying the overall process by preparing the catalyst in advance with optimized properties.
3Manufacturing precision
If the catalyst crystal structure is optimized for high selectivity, then the yield of acrylonitrile increases, but the production of side reaction products (CO2 and CO) may increase
Solution Approach 1:
The patent optimizes the crystal structure parameters of the catalyst by controlling the peak intensity ratios in XRD analysis (P/R and Q/R values). This parameter optimization enhances the catalyst's selectivity for acrylonitrile production while simultaneously suppressing side reactions that produce CO2 and CO, thereby improving manufacturing precision without increasing harmful byproducts.
Solution Approach 2:
The patent applies local quality principles by creating specific active sites on the catalyst surface through controlled oxidation states and surface composition. The catalyst comprises metal oxides in specific oxidation states that provide localized active sites highly selective for the desired ammoxidation reaction, while minimizing sites that would promote side reactions producing CO2 and CO.
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 efficiently converts ammonia, improving the productivity of acrylonitrile and hydrogen cyanide while optimizing the yield and proportion of acrylonitrile in the production process.
Implementation Method 1
a method in which propylene is subjected to ammoxidation is known. Through this ammoxidation, acrylonitrile and hydrogen cyanide can be obtained at the same time
Implementation Method 2
a step of spray-drying a slurry comprising Mo, Bi, and Fe to obtain a dried particle
Implementation Method 3
a step of calcining the dried particle in air
Data Source
AI summary
The present invention provides a catalyst including Mo, Bi, and Fe, wherein P/R is 0.10 or less, wherein P is a peak intensity at 2θ=22.9±0.2° and R is a peak intensity at 2θ=26.6±0.2°, in X-ray diffraction analysis.