Gold-Alumina Catalyst Shell Distribution
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Solution Overview
Problem
Existing heterogeneous catalysts with noble metals supported on silica and alumina do not offer improved properties for the process of preparing methyl methacrylate from methacrolein and methanol, necessitating a catalyst with enhanced characteristics.
Innovation Solution
A heterogeneous catalyst comprising alumina as a support with gold, where at least 90% of the gold is located in the outer 60% of the catalyst volume, and the catalyst particles have an average diameter ranging from 200 microns to 30 mm, optimized for improved performance in the production of methyl methacrylate through an oxidative esterification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gold is uniformly distributed throughout the catalyst volume, then the catalyst structure is simple and easy to manufacture, but the catalytic efficiency is reduced because gold in the inner core is underutilized
Solution Approach 1:
The patent applies local quality by creating a non-uniform gold distribution where the concentration of gold varies spatially within the catalyst particle. Specifically, gold is concentrated in the outer shell region while the inner core has reduced gold content, optimizing catalytic activity in the regions where reactants actually contact the catalyst surface.
Solution Approach 2:
The catalyst particle is segmented into distinct regions: an inner core region and an outer shell region with different gold concentrations. This segmentation allows the outer shell to provide high catalytic activity while the inner core provides structural support, thereby improving overall catalytic efficiency without requiring uniform gold distribution throughout the entire particle.
2Productivity
If more gold is used in the catalyst, then the catalytic activity increases, but the cost of the catalyst increases
Solution Approach 1:
By concentrating gold in the outer shell region where catalytic reactions occur, the patent achieves high catalytic activity with reduced overall gold content. The inner core uses less expensive materials, thereby reducing the total quantity of gold required while maintaining or improving catalytic performance.
Solution Approach 2:
The patent replaces expensive gold in the inner core region with cheaper alternative materials that provide structural support but do not need to exhibit high catalytic activity, since the primary catalytic function is performed by the gold-rich outer shell.
3Productivity
If smaller catalyst particles are used, then the surface area to volume ratio increases improving catalytic efficiency, but the pressure drop across the catalyst bed increases
Solution Approach 1:
The patent creates a size-dependent gold distribution where smaller particles have higher gold concentration in their outer shells compared to larger particles. This local optimization ensures that particles of all sizes maintain efficient catalytic activity per unit volume, allowing the use of larger overall particle sizes that reduce pressure drop while maintaining catalytic efficiency through enhanced gold positioning.
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 effectively enhances the production of methyl methacrylate by ensuring efficient distribution and utilization of gold within the catalyst particles, leading to improved selectivity and yield in the oxidative esterification reaction.
Implementation Method 1
The present invention is directed to a heterogeneous catalyst comprising a support and gold... The present invention is further directed to a method for preparing methyl methacrylate from methacrolein and methanol; said method comprising contacting a mixture comprising methacrolein, methanol and oxygen with a catalyst bed comprising particles of the heterogeneous catalyst.
Data Source
AI summary
A heterogeneous catalyst comprising a support and gold, wherein: (i) said support comprises alumina, (ii) said catalyst comprises from 0.1 to 5 wt % of gold, (iii) at least 90 wt % of the gold is in the outer 60% of catalyst volume, and (iv) particles of the catalyst have an average diameter from 200 microns to 30 mm; wherein weight percentages are based on weight of the catalyst.