Selective Ammoxidation Catalyst Bismuth Cerium Ratio
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Solution Overview
Problem
Current catalysts for the ammoxidation of propylene and isobutylene to produce acrylonitrile and methacrylonitrile have limitations in conversion efficiency and ammonia utilization, with the ratio of bismuth to cerium in bismuth-molybdenum-iron catalysts impacting performance but not fully optimized.
Innovation Solution
A mixed metal oxide catalyst composition with specific ratios of bismuth, molybdenum, iron, and cerium, along with additional promoters, is developed to enhance conversion efficiency and ammonia utilization, characterized by the formula Mo m Bi a Fe b A c D d E e F f G g Ce h O x, where a, b, c, d, e, f, g, and h are within defined atomic ratios, optimizing the bismuth to cerium ratio for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bismuth to cerium ratio in the catalyst is not optimized, then the catalyst composition is simpler, but the conversion efficiency and ammonia utilization are lower
Solution Approach 1:
The patent applies parameter changes by optimizing the atomic ratio of bismuth to cerium within the specific range of 0.45 ≤ a/h < 1.5. This quantitative adjustment of compositional parameters resolves the contradiction by achieving high conversion efficiency and ammonia utilization while maintaining a controlled catalyst formulation.
Solution Approach 2:
The patent employs composite materials by creating a multi-element catalyst system comprising Mo, Bi, Fe, A, D, E, F, G, and Ce in specific ratios. This composite approach combines multiple metal oxides to achieve synergistic effects that improve productivity while the defined compositional constraints prevent excessive complexity.
2Productivity
If the bismuth to cerium ratio is not optimized, then the catalyst preparation is easier, but the ammonia utilization efficiency is lower
Solution Approach 1:
The patent optimizes the bismuth to cerium atomic ratio parameter within the range 0.45 ≤ a/h < 1.5 to achieve high ammonia utilization efficiency. This parameter optimization balances the trade-off between preparation simplicity and catalytic performance by establishing clear compositional guidelines.
3Productivity
If the catalyst uses conventional compositions, then the catalyst structure is simpler, but the catalytic activity and conversion are lower
Solution Approach 1:
The patent employs composite materials by formulating a catalyst with multiple metal oxides (Mo, Bi, Fe, A, D, E, F, G, Ce) in specific atomic ratios. This composite structure enhances overall conversion through synergistic interactions while the defined ratio constraints (0.45 ≤ a/h < 1.5) maintain structural manageability.
Solution Approach 2:
The patent applies local quality by assigning specific functional roles to different metal oxide components within the catalyst. The bismuth and cerium components are optimized in specific ratios to provide particular catalytic functions, while other elements (A, D, E, F, G) contribute specialized properties, creating a functionally differentiated composite material.
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 higher overall conversion of propylene and isobutylene to nitriles, increased hydrogen cyanide production, and improved ammonia utilization efficiency, with specific bismuth to cerium ratios enhancing attrition resistance and catalytic activity.
Implementation Method 1
Catalysts containing oxides of iron, bismuth and molybdenum, promoted with suitable elements, have long been used for the conversion of propylene and/or isobutylene at elevated temperatures in the presence of ammonia and oxygen (usually in the form of air) to manufacture acrylonitrile and/or methacrylonitrile
Implementation Method 2
ammoxidation of propylene and/or isobutylene to the corresponding unsaturated nitrile
Data Source
AI summary
A catalytic composition useful for the conversion of an olefin selected from the group consisting of propylene, isobutylene or mixtures thereof, to acrylonitrile, methacrylonitrile, and mixtures thereof. The catalytic composition comprises a complex of metal oxides comprising bismuth, molybdenum, iron, cerium and other promoters, wherein the ratio of bismuth to cerium ratio in the composition is greater than or equal to 0.45 and less than or equal to 1.5.