Mixed Oxide Catalyst for HCN Production in Acrylonitrile Effluent
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Solution Overview
Problem
Current catalysts for producing hydrogen cyanide (HCN) and acetonitrile (ACN) in acrylonitrile manufacturing processes are inefficient, requiring high temperatures, leading to reduced selectivity and catalyst stability, and are not optimized for low carbon alcohol feeds, resulting in suboptimal yields and increased maintenance costs.
Innovation Solution
A novel mixed oxide catalyst composition represented by formulas (I) and (II) is developed, which is used in a secondary reactor to enhance HCN production and NH3 removal from AN reactor effluent streams, allowing for lower operating temperatures, higher selectivity, and longer catalyst life, while also converting unconverted NH3 and O2 to HCN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for HCN and ACN production in acrylonitrile manufacturing, then the production process can operate, but high temperatures are required which reduce selectivity and catalyst stability
Solution Approach 1:
The patent modifies the chemical composition parameters of the catalyst by incorporating specific metal oxides (Fe, Mo, Bi, Sb, P) in optimized ratios, and adjusts operational parameters such as operating temperature to lower ranges where the improved catalyst maintains high activity. This allows the system to achieve the same productivity at milder conditions, thereby improving catalyst stability and selectivity.
Solution Approach 2:
The patent employs a composite catalyst system consisting of multiple metal oxides (Fe-Mo-Bi-Sb-P) rather than a single catalyst material. This composite structure synergistically combines the properties of individual components to enhance catalytic activity, selectivity, and thermal stability, resolving the contradiction between productivity and catalyst stability.
2Productivity
If conventional catalysts are used, then the process can run, but selectivity is reduced due to high temperature operation
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst to include specific ratios of Fe, Mo, Bi, Sb, and P oxides, which are optimized to promote selective HCN and ACN formation. The operating temperature parameter is also adjusted to lower ranges where the improved catalyst maintains high activity, thereby achieving both high productivity and high selectivity simultaneously.
Solution Approach 2:
The patent converts the previously harmful effect of high temperatures (which reduced selectivity) into a benefit by developing a catalyst that is specifically designed to be active at lower temperatures. This allows the system to operate in a temperature range that favors selective product formation while maintaining high productivity.
3Quantity of substance
If methanol is added to increase HCN production, then HCN yield increases, but catalyst lifetime is reduced
Solution Approach 1:
The patent modifies the catalyst composition parameters to include components (particularly Bi and Sb oxides) that are more resistant to deactivation by methanol and its derivatives. This compositional change allows the catalyst to maintain its activity and structure even in the presence of methanol, thereby extending catalyst lifetime while permitting higher HCN production.
Solution Approach 2:
The patent develops a catalyst formulation that is more tolerant to harsh operating conditions and methanol addition, effectively making the catalyst more durable and less susceptible to becoming a 'short-living' component. This resolves the issue where methanol addition previously forced frequent catalyst replacement.
4Manufacturing precision
If unconverted NH3 is removed from AN reactor effluent, then product purity improves, but additional processing steps are required
Solution Approach 1:
The patent makes the catalyst perform multiple functions: it catalyzes both the ammoxidation reaction to produce AN and simultaneously converts unconverted NH3 to HCN or ACN. This multi-functionality eliminates the need for separate NH3 removal steps, achieving product purification while maintaining process simplicity.
Solution Approach 2:
The catalyst system serves itself by utilizing the unconverted NH3 in the effluent stream as an additional feedstock for HCN/ACN production. Instead of requiring external removal and separate processing, the system self-purifies the effluent while generating additional valuable products, thereby improving purity without adding process complexity.
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 composition significantly improves HCN yields, extends catalyst life, and reduces maintenance needs by operating at lower temperatures with higher selectivity, effectively utilizing AN reactor effluent streams to produce HCN and ACN, thus optimizing the production process.
Implementation Method 1
A novel mixed oxide catalyst composition represented by formulas (I) and (II) is developed, which is used in a secondary reactor to enhance HCN production and NH3 removal from AN reactor effluent streams
Implementation Method 2
converting unconverted NH3 and O2 to HCN
Data Source
AI summary
The present invention relates to catalyst compositions containing a mixed oxide catalyst of formula (I) or formula (II) as described herein, their preparation, and their use in a process for ammoxidation of various organic compounds to their corresponding nitriles and to the selective catalytic oxidation of excess NH3 present in effluent gas streams to N2 and/or NOx.