Oxide Catalyst Production via Particle Size Control
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Solution Overview
Problem
Existing processes for producing oxide catalysts for vapor-phase catalytic oxidation or ammoxidation of propane or isobutane face challenges in achieving favorable yield and stability due to issues with catalyst performance, particularly related to particle size distribution and reduction ratio, especially during large-scale continuous calcining.
Innovation Solution
A process involving the preparation of a catalyst raw material mixture with specific atomic ratios of Mo, V, and Nb, followed by drying and calcining in an inert gas atmosphere, with a controlled particle size distribution to ensure a mean particle diameter of 35 to 70 μm and a content of particles ≤25 μm of 20% or less, to stabilize the catalyst performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If catalyst particles with small diameter (≤25 μm) are present in large amounts, then catalyst fluidity and fluidized bed performance are improved, but catalyst loss due to dispersion and coverage of reaction apparatus increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters - specifically limiting particles ≤25 μm to 2% by mass or less and setting mean particle diameter to 35-70 μm. This quantitative parameter control resolves the contradiction by finding the optimal balance point where fluidity is sufficient while catalyst loss is minimized.
2Loss of substance
If catalyst particles with larger diameter are used, then catalyst loss is reduced, but catalyst fluidity and fluidized bed performance deteriorate
Solution Approach 1:
The patent resolves this contradiction by optimizing the particle size parameters within specific ranges - mean particle diameter of 35-70 μm and limited fine particles. This parameter optimization ensures that particles are not too large to lose fluidity while not too small to cause excessive loss, achieving a balanced performance.
3Productivity
If reduction ratio is increased to improve catalyst activity, then reaction performance improves, but manufacturing precision and stability during large-scale production become difficult to control
Solution Approach 1:
The patent addresses this contradiction by controlling multiple parameters simultaneously - particle size distribution (mean diameter 35-70 μm, fine particles ≤2% by mass) and reduction ratio (8-12%). This multi-parameter control approach ensures that high catalyst activity is achieved while maintaining manufacturing precision and stability during large-scale continuous calcining operations.
4Ease of operation
If particle size is reduced to improve fluidity, then fluidized state is favorable, but catalyst loss due to dispersion increases
Solution Approach 1:
The patent resolves this contradiction through precise parameter control of particle size distribution - limiting particles ≤25 μm to 2% by mass or less while maintaining mean particle diameter of 35-70 μm. This parameter specification ensures adequate fluidity for good fluidized state while preventing excessive catalyst loss from dispersion.
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
This approach enables the production of oxide catalysts with improved yield and stability, effectively addressing the limitations of previous methods by ensuring favorable reaction performance and reducing catalyst loss.
Implementation Method 1
drying the catalyst raw material mixture
Implementation Method 2
calcining the catalyst precursor in an inert gas atmosphere
Implementation Method 3
a content of particles having a particle diameter of 25 μm or less is 2% by mass or less and a mean particle diameter is 35 to 70 μm, in an inert gas atmosphere
Data Source
AI summary
An object of the present invention is to provide a process for producing an oxide catalyst used in a vapor-phase catalytic oxidation or vapor-phase catalytic ammoxidation reaction of propane or isobutene, which enables a catalyst demonstrating favorable yield to be stably produced. According to the present invention, there is provided a process for producing an oxide catalyst used in a vapor-phase catalytic oxidation or vapor-phase catalytic ammoxidation reaction of propane or isobutane, comprising the steps of: (i) preparing a catalyst raw material mixture containing Mo, V and Nb and satisfying the relationships of 0.1≦a≦1 and 0.01≦b≦1 when atomic ratios of V and Nb to one atom of Mo are defined as a and b, respectively; (ii) drying the catalyst raw material mixture; and (iii) calcining a particle, in which a content of the particle having a particle diameter of 25 μm or less is 20% by mass or less and a mean particle diameter is from 35 to 70 μm, in an inert gas atmosphere.