Ammoxidation Catalyst Preparation via pH-Controlled Mixing
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Solution Overview
Problem
Current methods for producing ammoxidation catalysts struggle to achieve significant improvements in acrylonitrile yield, despite variations in metal composition and catalyst preparation steps.
Innovation Solution
A method involving the preparation of a precursor slurry with specific pH ranges and mixing times, followed by drying and calcination, to produce an ammoxidation catalyst with a composition represented by Mo12BiaFebXcYdZeOf, where X, Y, and Z are additional elements, and the catalyst is supported on silica, enhancing acrylonitrile selectivity and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal composition is varied to improve acrylonitrile yield, then catalyst activity improves, but further improvement becomes difficult
Solution Approach 1:
The patent changes the preparation parameters of the catalyst, specifically controlling the pH during mixing (maintaining pH 2-4) and the mixing time (1-70 seconds), rather than varying the metal composition. This parameter control enables continued improvement in acrylonitrile yield by optimizing the physical and chemical state of the catalyst during preparation, resolving the plateau effect observed with composition variations.
2Stability of the object's composition
If mixing time is extended to ensure homogeneous catalyst composition, then composition uniformity improves, but aggregation of metal particles increases
Solution Approach 1:
The patent maintains continuous mixing at a controlled speed throughout the addition of solutions, ensuring homogeneous distribution of metal components. The mixing continues for a specific duration (1-70 seconds) to achieve uniform composition without excessive aggregation, balancing composition uniformity with particle size control through optimized continuous action.
Solution Approach 2:
The patent optimizes the mixing time parameter (1-70 seconds) and pH parameter (2-4) to achieve the desired balance between composition uniformity and particle aggregation. By controlling these parameters, the patent prevents excessive aggregation while ensuring homogeneous catalyst composition.
3Productivity
If pH is adjusted to optimize catalyst formation, then acrylonitrile selectivity improves, but process complexity increases
Solution Approach 1:
The patent utilizes the natural pH change that occurs during the mixing process (pH passes through 2-4) and maintains this range through simple buffer solutions or controlled addition rates. This approach achieves high acrylonitrile selectivity without requiring complex pH control systems, as the pH control is achieved through straightforward chemical means rather than sophisticated instrumentation.
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 method results in a high acrylonitrile yield and improved propylene activity in the ammoxidation reaction, with the catalyst exhibiting high selectivity and stability due to controlled aggregation of metal and silica particles.
Implementation Method 1
a drying step of obtaining a dry particle from the precursor slurry
Implementation Method 2
a calcination step of calcining the dry particle
Implementation Method 3
the time during which a pH of a mixture passes through a particular range having an upper limit and a lower limit while the second solution or slurry is mixed
Data Source
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AI summary
A method for producing an ammoxidation catalyst, comprising: a step of preparing a precursor slurry that is a precursor of the catalyst; a drying step of obtaining a dry particle from the precursor slurry; and a calcination step of calcining the dry particle, wherein the step of preparing the precursor slurry is a step of mixing a first solution or slurry having a first pH and a second solution or slurry to obtain a solution or slurry having a second pH after completion of mixing, a time during which a pH of a mixture passes through a particular range having an upper limit and a lower limit while the second solution or slurry is mixed is 1-70 seconds, he upper limit and the lower limit being designated as a third pH and a fourth pH respectively, and the third pH and the fourth pH are set between the first pH and the second pH.