Mixed Oxide Catalyst Mechanical Strength via Reduction Treatment
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Solution Overview
Problem
Catalysts composed of mixed oxides of molybdenum, bismuth, and iron used in gas phase catalytic oxidation reactions often have insufficient mechanical strength, leading to breakage during reactor filling and pressure drops, which affects the stability of unsaturated aldehyde and unsaturated carboxylic acid production.
Innovation Solution
A method involving the steps of calcining an aqueous solution or slurry containing catalyst raw materials in a molecular oxygen-containing atmosphere, followed by a reduction treatment to achieve a specific mass loss, and a second calcination in a molecular oxygen-containing atmosphere to enhance the mechanical strength of the catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a catalyst composed of mixed oxide comprising molybdenum, bismuth and iron is prepared by conventional drying and calcining methods, then the catalyst can be produced with standard preparation procedures, but the catalyst has low mechanical strength and breaks easily during reactor filling
Solution Approach 1:
The patent applies preliminary action by performing a reduction treatment before the final calcination step. The calcined product is heated in the presence of a reducing material to obtain a reduced product, which is then secondly calcined. This preliminary reduction step modifies the catalyst structure in advance to improve mechanical strength while maintaining the simplicity of the overall preparation process.
Solution Approach 2:
The patent changes the physical and chemical parameters of the catalyst during preparation by controlling the mass loss during reduction treatment to be within a specific range (0.05 to 6%). By adjusting parameters such as reduction temperature, reducing material type, and calcination conditions, the catalyst achieves optimal mechanical strength without complicating the manufacturing process.
2Device complexity
If the catalyst has low mechanical strength, then the catalyst preparation process is simpler, but the catalyst breaks during reactor filling causing pressure drop in the reactor
Solution Approach 1:
The reduction treatment is performed as a preliminary action before final catalyst formation. By heating the calcined product in the presence of a reducing material to achieve a mass loss of 0.05 to 6%, the catalyst structure is pre-modified to enhance its mechanical properties and stability, preventing breakage during reactor filling and operation.
Solution Approach 2:
The patent changes the chemical state of the catalyst by controlling the reduction and re-oxidation process. The specific mass loss range (0.05 to 6%) during reduction serves as a critical parameter control mechanism that ensures the catalyst achieves the necessary mechanical strength and reliability for stable reactor operation without increasing process complexity.
3Ease of manufacture
If conventional catalyst preparation methods are used, then the preparation process is straightforward, but the catalyst requires frequent replacement due to breakage and pressure drop
Solution Approach 1:
The reduction treatment serves as a preliminary action that enhances catalyst durability before the catalyst is put into service. By performing this additional heating step with controlling mass loss within 0.05 to 6%, the catalyst structure is strengthened, reducing breakage and pressure drop issues during production, thereby improving production stability without significantly complicating the preparation process.
Solution Approach 2:
The patent uses parameter changes in the reduction and calcination steps to optimize catalyst performance. By controlling the mass loss during reduction to fall within the specific range of 0.05 to 6%, and by adjusting reduction temperature and calcination conditions, the catalyst achieves improved mechanical strength and production stability while maintaining ease of manufacture.
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 significantly improves the mechanical strength of the catalyst, preventing breakage during reactor filling and reducing pressure drops, allowing for stable production of unsaturated aldehydes and carboxylic acids through gas phase catalytic oxidation.
Implementation Method 1
heating the calcined product obtained in Step (1) in the presence of a reducing material to obtain a reduced product having a mass loss, represented by the following equation (I), of 0.05 to 6%
Implementation Method 2
drying an aqueous solution or an aqueous slurry containing raw materials of the catalyst
Implementation Method 3
firstly calcining a dried product in a molecular oxygen-containing gas atmosphere to obtain a calcined product
Data Source
AI summary
A catalyst for use in the production of an unsaturated aldehyde and/or an unsaturated carboxylic acid, the catalyst comparing (or, preferably, being composed of) a mixed oxide containing molybdenum, bismuth and iron, which has improved methanical strength, is produced by a method including the steps of (1) drying an aqueous solution or an aqueous slurry containing raw materials of the catalyst and then firstly calcining a dried product in a molecular oxygen-containing gas atmosphere to obtain a calcined product; (2) heating the calcined product obtained in Step (1) in the presence of a reducing material to obtain a reduced product having a mass loss of 0.05 to 6%; and (3) secondly calcining the reduced product obtained in Step (2) in a molecular oxygen-containing gas atmosphere.