Fluid Bed Ammoxidation Catalyst Composition for Acrylonitrile Yield
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Solution Overview
Problem
Conventional catalysts for acrylonitrile production in ammoxidation reactions face challenges in achieving high yield without excessive ammonia usage, leading to byproduct formation and increased disposal costs, with existing catalysts being insufficient in maintaining performance over time.
Innovation Solution
A catalyst composition for fluidized bed ammoxidation reactions, comprising a composite metal oxide with specific atomic ratios of elements like molybdenum, bismuth, iron, nickel, cobalt, cerium, and alkali metals, supported on silica, optimized to enhance reaction yield and stability while minimizing ammonia consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for ammoxidation reaction, then acrylonitrile production can proceed, but byproducts are formed and disposal costs increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the atomic ratios of multiple metal elements (Mo: 0.5-2.0, Bi: 0.3-1.0, Fe: 0.5-2.0, Ni: 0.2-0.8, Co: 0.2-0.8, Ce: 0.1-0.5, Rb: 0.05-0.3, K: 0.05-0.3) in the catalyst composition. This optimized parameter combination enhances the selectivity of the ammoxidation reaction, increasing acrylonitrile yield while suppressing byproduct formation through improved reaction pathway control
Solution Approach 2:
The patent employs composite materials by creating a multi-element metal oxide catalyst system comprising molybdenum, bismuth, iron, nickel, cobalt, cerium, and alkali metals (rubidium and/or potassium). This composite catalyst structure synergistically combines multiple elements to achieve high acrylonitrile selectivity and reduced byproduct generation, overcoming the limitations of conventional single-element or simpler composite catalysts
2Productivity
If ammonia is used in excess to improve acrylonitrile yield, then reaction performance increases, but disposal load and environmental impact increase
Solution Approach 1:
The patent utilizes parameter changes by optimizing the atomic ratio of alkali metals (Rb: 0.05-0.3, K: 0.05-0.3) relative to other catalyst elements. This precise parameter adjustment enhances the catalyst's ability to promote ammonia utilization efficiency, achieving high acrylonitrile yields with reduced ammonia consumption and minimized unreacted ammonia requiring disposal
Solution Approach 2:
The catalyst design incorporates self-service principles by creating a balanced multi-element composition that inherently optimizes ammonia conversion during the ammoxidation reaction. The synergistic interaction among Mo, Bi, Fe, Ni, Co, Ce, and alkali metals enables the catalyst to efficiently utilize ammonia feedstock, reducing waste and disposal requirements without external intervention
3Reliability
If conventional catalysts are used, then initial reaction activity can be achieved, but performance degrades over time
Solution Approach 1:
The patent applies composite materials by formulating a multi-element metal oxide catalyst system where molybdenum serves as the base metal combined with bismuth, iron, nickel, cobalt, cerium, and alkali metals. This composite structure provides enhanced thermal stability and structural integrity, maintaining catalytic activity and selectivity over extended operation periods without significant performance degradation
Solution Approach 2:
The patent implements local quality by assigning specific functional roles to different metal elements within the catalyst composition. Molybdenum provides the base catalytic activity, while bismuth, iron, nickel, cobalt, and cerium contribute to structural stability and resistance against sintering and deactivation. The alkali metals (Rb, K) locally enhance ammonia activation and utilization. This differentiated functional distribution ensures long-term reliability and stability
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 achieves high and stable acrylonitrile yield with reduced byproduct formation, even under conditions of excessive ammonia, maintaining performance over long periods and improving handling and environmental aspects.
Implementation Method 1
a catalyst for a fluidized bed ammoxidation reaction... a method for producing acrylonitrile by reacting propylene with molecular oxygen and ammonia (ammoxidation reaction)
Data Source
AI summary
A catalyst for a fluidized bed ammoxidation reaction containing silica and a metal oxide, wherein a composite of the silica and the metal oxide is represented by the following formula (1). Mo12BiaFebNicCodCeeCrfXgOh/(SiO2) A ................. (1) (in formula (1), X represents at least one element selected from the group consisting of K, Rb, and Cs, 0.1≤a≤1, 1≤b≤3, 1≤c≤6.5, 1≤d≤6.5, 0.2≤e≤1.2, f≤0.05, and 0.05≤g≤1 are satisfied, h satisfies valences of constituent elements excluding silica, A represents a content of silica (% by mass) and satisfies 35≤A≤48, and values of α, β, and γ calculated from the following expressions (2), (3), and (4) satisfy 0.03≤α≤0.08, 0.2≤β≤0.4, and 0.5≤γ≤2.) α=1.5a/1.5b+f+c+d β=1.5b+f/c+d γ=d/c