Alpha-Alumina Catalyst Carrier Pore Optimization
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Solution Overview
Problem
Current olefin epoxidation catalysts face challenges in maintaining selectivity and stability over time, leading to reduced efficiency and the need for increased reaction temperatures, which limits catalyst lifespan and product output.
Innovation Solution
A catalyst with a carrier having a surface area of at least 1 m2/g and a pore size distribution where at least 80% of the pore volume is in pores with diameters between 0.1 and 10 μm, optimized by using a mixture of alpha-alumina particles and an alkaline earth metal silicate bond material, enhances silver deposition and catalyst performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the carrier surface area is increased to provide more deposition area for silver, then the activity should improve, but the selectivity deteriorates due to increased combustion reactions
Solution Approach 1:
The patent applies porous materials by carefully controlling the pore size distribution of the alpha-alumina carrier, specifying that pores with diameters of 0.5-10 μm should constitute 60-90% of total pore volume. This porous structure provides adequate surface area for silver deposition while the controlled pore dimensions prevent excessive combustion reactions, thereby maintaining both high activity and selectivity simultaneously
Solution Approach 2:
The patent applies parameter changes by precisely defining physical parameters of the carrier including surface area (1-10 m²/g), pore size distribution (0.5-10 μm pores comprising 60-90% of total pore volume), and particle size (0.5-5 mm). These parameter optimizations enable the catalyst to achieve improved activity through adequate silver deposition area while maintaining selectivity through controlled pore dimensions that limit combustion pathways
2Productivity
If the reaction temperature is increased to maintain olefin oxide production as catalyst ages, then productivity is maintained, but selectivity deteriorates and energy consumption increases
Solution Approach 1:
The patent applies preliminary action by pre-optimizing the carrier properties before catalyst operation begins. The carrier is designed with specific surface area (1-10 m²/g) and pore size distribution (0.5-10 μm pores at 60-90% of total pore volume) to ensure uniform silver deposition and efficient mass transfer from the start. This preliminary optimization allows the catalyst to maintain high selectivity throughout its operational life without requiring temperature increases
3Reliability
If high purity alpha-alumina is used as carrier, then catalyst selectivity improves, but the beneficial effect of minor impurities is lost
Solution Approach 1:
The patent applies local quality by specifying that the carrier be formed predominantly of alpha-alumina (greater than 90 weight percent) to ensure high selectivity, while allowing controlled amounts of specific impurities (alkali and alkaline earth metals at 0.01-1000 ppm, silica at 0.1-10 wt%) to provide beneficial effects on activity. This localized control of composition enables simultaneous optimization of both selectivity and activity
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 optimized catalyst exhibits improved activity, selectivity, and stability, allowing for longer catalyst operation at lower temperatures and increased product yield, addressing the limitations of previous catalysts.
Implementation Method 1
a catalyst which comprises a carrier and silver deposited on the carrier, which carrier has a surface area of at least 1 m2/g, and a pore size distribution wherein at least 80% of the total pore volume is contained in pores with diameters in the range of from 0.1 to 10 μm
Implementation Method 2
In olefin epoxidation, a feed containing an olefin and an oxygen source is contacted with a catalyst under epoxidation conditions. The olefin is reacted with oxygen to form an olefin oxide.
Data Source
AI summary
The invention provides a process for the epoxidation of an olefin, which process comprises reacting a feed comprising an olefin and oxygen in the presence of a catalyst comprising a carrier and silver deposited on the carrier, which carrier comprises at least 85 weight percent α-alumina and has a surface area of at least 1.3 m2/g, a median pore diameter of more than 0.8 μm, and a pore size distribution wherein at least 80% of the total pore volume is contained in pores with diameters in the range of from 0.1 to 10 μm and at least 80% of the pore volume contained in the pores with diameters in the range of from 0.1 to 10 μm is contained in pores with diameters in the range of from 0.3 to 10 μm.