Alpha Alumina Catalyst Carrier for Olefin Epoxidation
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Solution Overview
Problem
Existing catalyst carriers for olefin epoxidation reactions face challenges in achieving high selectivity and longevity while maintaining resistance to crushing and abrasion, due to the conflicting requirements of porosity and physical robustness, often resulting in carriers with undesirable impurities that impact catalyst performance.
Innovation Solution
A carrier composed of at least 85 wt% alpha alumina, with controlled silica and sodium content, and a specific water absorption and surface area ratio, combined with a monomodal or bimodal pore distribution, supports a silver catalyst with a controlled silver loading, enhancing selectivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the carrier porosity is increased to improve catalyst selectivity and longevity, then the catalyst performance is improved, but the resistance to crushing and abrasion deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the water absorption parameter (0.20-0.40 g/g) and surface area parameter (0.50-1.50 m²/g) of the alpha alumina carrier to achieve optimal balance between porosity for catalyst performance and structural integrity for mechanical strength. This quantitative parameter optimization resolves the contradiction between improved catalyst selectivity/longevity and resistance to crushing/abrasion.
Solution Approach 2:
The patent uses composite materials by combining alpha alumina with controlled amounts of silica (0.06-0.40 wt%) and limiting sodium content (≤0.04 wt%), creating a composite carrier structure that enhances both porosity for catalytic activity and mechanical strength for durability. The composite composition achieves synergistic effects that simultaneously improve catalyst performance and structural resistance.
2Productivity
If the carrier surface area and water absorption are increased to improve silver loading and catalyst activity, then the catalyst productivity is improved, but the manufacturing cost increases due to impurity control requirements
Solution Approach 1:
The patent applies parameter changes by optimizing the water absorption (0.20-0.40 g/g) and surface area (0.50-1.50 m²/g) parameters to achieve optimal silver loading capacity while controlling manufacturing costs. These parameter ranges maximize catalyst productivity without requiring excessive impurity control measures that would increase manufacturing complexity and cost.
Solution Approach 2:
The patent applies local quality by controlling the local chemical composition (silica content 0.06-0.40 wt%, sodium content ≤0.04 wt%) in specific regions of the carrier structure to optimize silver deposition properties. This localized compositional control enhances catalyst activity and silver loading efficiency while avoiding uniform impurity control throughout the entire carrier that would increase manufacturing costs.
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 solution provides a physically robust carrier that maintains high selectivity and longevity, reducing manufacturing costs by optimizing silver loading and minimizing impurity effects, thereby improving the economic performance of the reactor system.
Implementation Method 1
The catalyst usually comprises a catalytically active material, such as silver, deposited on a plurality of ceramic pellets
Implementation Method 2
The carrier has a water absorption no greater than 0.35 gram of water/gram of carrier
Data Source
AI summary
The carrier of the present invention includes at least 85 wt percent alpha alumina, at least 0.06 wt percent SiO2 and no more than 0.04 wt percent Na2O. The carrier has a water absorption no greater than 0.35 g/g and a ratio of water absorption (g/g) to surface area (m2/g) no greater than 0.50 g/m2. Another aspect of the invention is a catalyst for the epoxidation of olefins which comprises the above described carrier and silver dispersed thereon, where the carrier has a monomodal, bimodal or multimodal pore distribution and where the quantity of silver is between 5 and 50 wt/%, relative to the weight of the catalyst. A reactor system for the epoxidation of olefins is also disclosed.