Noble Metal Shell Catalyst for Methyl Methacrylate Selectivity
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Solution Overview
Problem
Existing methods for producing methyl methacrylate from methacrolein and methanol using heterogeneous catalysts with noble metals lack sufficient selectivity and efficiency in oxidative esterification reactions.
Innovation Solution
A method involving a catalyst bed with a support and noble metals, where the noble metals are concentrated in the outer region, and oxygen is contacted with a mixture of methacrolein and methanol in a reactor, optimizing the mass transfer rate of oxygen to enhance the space-time yield of methyl methacrylate, with specific conditions for reactor design and catalyst properties to improve selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heterogeneous catalysts with noble metals are used in oxidative esterification reactions, then catalytic activity is provided, but selectivity is insufficient
Solution Approach 1:
The patent applies local quality by concentrating noble metals specifically in the outer region of the catalyst particle rather than uniformly distributing them throughout. This creates a spatial gradient where the outer region has high catalytic activity for the desired reaction while the inner region provides structural support. The outer region concentration of noble metals enhances selectivity by providing sufficient active sites at the particle surface where reactants first contact the catalyst, while the reduced overall noble metal content improves space-time yield by lowering cost and potentially reducing side reactions.
2Productivity
If oxygen mass transfer rate is increased to improve space-time yield, then productivity increases, but selectivity may be compromised
Solution Approach 1:
The patent resolves this contradiction by creating local quality differentiation within the catalyst particle. The outer region is enriched with noble metals to provide high selectivity at the reaction interface where oxygen mass transfer occurs, while the inner region contains less noble metal but provides structural integrity. This spatial distribution allows the system to achieve high space-time yield through improved oxygen mass transfer without sacrificing selectivity, because the noble metals are positioned exactly where they are most needed - at the outer surface where reactants contact the catalyst.
3Productivity
If noble metal content is increased to improve catalytic activity, then reaction efficiency increases, but cost and potential side reactions increase
Solution Approach 1:
The patent applies local quality by strategically concentrating noble metals in the outer region of the catalyst particle rather than uniformly distributing them throughout the entire particle volume. This spatial distribution ensures that noble metals are positioned where they can most effectively catalyze the desired oxidative esterification reaction at the particle surface, maximizing reaction efficiency. Simultaneously, the reduced overall noble metal content (concentrated in the outer shell rather than throughout) reduces cost and minimizes side reactions that could lead to byproduct formation such as methyl isobutyrate.
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 achieves improved selectivity and efficiency in producing methyl methacrylate, reducing byproducts like methyl isobutyrate, with optimized oxygen mass transfer rates and catalyst configurations, leading to higher yields and process efficiency.
Implementation Method 1
contacting in a reactor a mixture comprising methacrolein, methanol and oxygen with a catalyst bed of heterogeneous catalyst comprising a support and a noble metal
Implementation Method 2
mass transfer rate of oxygen kLa/STY is at least 20 kg catalyst/mole MMA, preferably at least 25 kg catalyst/mole MMA
Data Source
AI summary
A method for preparing methyl methacrylate from methacrolein and methanol; said method comprising contacting in a reactor a mixture comprising methacrolein, methanol and oxygen with a catalyst bed of heterogeneous catalyst comprising a support and a noble metal, wherein mass transfer rate of oxygen in hour-1 divided by space-time yield in moles methyl methacrylate/kg.catalyst hour in the catalyst bed is at least 25 kg catalyst/mole methyl methacrylate.