Bismuth Distribution Control in Mo-Bi-Co Catalyst for Selective Oxidation
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Solution Overview
Problem
Existing catalysts for producing α,β-unsaturated aldehydes and α,β-unsaturated carboxylic acids via hydrocarbon oxidation lack sufficient selectivity, necessitating an improvement in catalyst performance.
Innovation Solution
A catalyst comprising molybdenum, bismuth, and cobalt, with specific bismuth concentration ratios and X-ray diffraction patterns, is developed to enhance selectivity in oxidation reactions, ensuring uniform bismuth distribution and optimal crystalline phase proportions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional catalysts containing molybdenum and bismuth are used for hydrocarbon oxidation, then the oxidation reaction can proceed, but the selectivity for producing α,β-unsaturated aldehyde and/or carboxylic acid is insufficient
Solution Approach 1:
The patent applies local quality by creating specific spatial distribution patterns of bismuth within the catalyst particles. Through controlled preparation methods, bismuth is concentrated in particular regions (white parts in SEM images) rather than uniformly distributed, creating local areas with enhanced catalytic activity for the desired oxidation reaction, thereby improving selectivity and target product yield
Solution Approach 2:
The patent employs parameter changes by precisely controlling the bismuth concentration distribution through quantitative analysis parameters. Specific criteria are established: (x2-x1)/σ1 ≤ 0.8, x1 ≥ 0.01, and x2 ≤ 3.0, where x1 and x2 represent bismuth concentrations in different regions. These parameter constraints ensure optimal catalyst structure for high selectivity in producing α,β-unsaturated aldehyde and/or carboxylic acid
2Speed
If bismuth concentration is increased to improve catalytic activity, then reaction rate increases, but sequential reactions occur reducing target product selectivity
Solution Approach 1:
The patent resolves this contradiction by creating local quality differentiation in bismuth distribution. High bismuth concentration areas (white parts) provide sufficient catalytic activity for rapid reaction, while low bismuth concentration areas (black parts) prevent excessive sequential reactions. This spatial heterogeneity allows the catalyst to maintain high reaction rate while preserving target product selectivity
Solution Approach 2:
The patent applies partial action by providing just enough bismuth in specific regions to achieve the desired catalytic activity without excessive bismuth that would cause sequential reactions. The controlled concentration ranges (x1 ≥ 0.01, x2 ≤ 3.0) ensure sufficient catalysis while avoiding over-oxidation, thereby maintaining product selectivity
3Stability of the object's composition
If uniform bismuth distribution is achieved, then catalyst stability is improved, but catalytic activity for oxidation reaction decreases
Solution Approach 1:
The patent resolves this contradiction by rejecting uniform distribution in favor of controlled non-uniform distribution. The specific criterion (x2-x1)/σ1 ≤ 0.8 with defined concentration ranges creates localized bismuth enrichment that enhances catalytic activity while maintaining overall catalyst stability. This local quality approach allows the catalyst to be both stable and highly active
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 high selectivity in producing α,β-unsaturated aldehydes and α,β-unsaturated carboxylic acids, inhibiting sequential reactions and improving target product yield.
Implementation Method 1
a catalyst used for producing, by an oxidation reaction of a hydrocarbon, a corresponding α,β-unsaturated aldehyde and/or α,β-unsaturated carboxylic acid
Implementation Method 2
oxidation reaction of a hydrocarbon
Implementation Method 3
a reflected electron image of the catalyst, which is obtained using a scanning electron microscope (SEM)
Implementation Method 4
performing an energy dispersive X-ray spectroscopy (EDS) analysis
Implementation Method 5
in an X-ray diffraction pattern, when the intensity of a maximum peak (peak A) in a range of 2θ (X-ray diffraction angle)=26.5°±0.3° is defined as IA
Data Source
AI summary
An object of the present invention is mainly to provide a catalyst with which an α,β-unsaturated aldehyde and/or an α,β-unsaturated carboxylic acid can be produced with a high selectivity. Provided is a catalyst used for producing, by an oxidation reaction of a hydrocarbon, a corresponding α,β-unsaturated aldehyde and/or α,β-unsaturated carboxylic acid, and the catalyst contains molybdenum, bismuth, and cobalt, and satisfies the following Formula (I-1): (x2−x1)/σ1≤1.5 (I-1) In Formula (I-1), x1, x2, and σ1 are values obtained by binarizing a reflected electron image of the catalyst, which is obtained using a scanning electron microscope (SEM) at an accelerating voltage of 15 kV, into black and white and subsequently performing an energy dispersive X-ray spectroscopy (EDS) analysis; x1 represents a bismuth concentration [% by mass] in black parts; x2 represents a bismuth concentration [% by mass] in white parts; and σ1 represents a standard deviation of the bismuth concentration in the black parts.