Hierarchical Metallophosphates for Microporosity and Molecular Diffusion
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Solution Overview
Problem
Existing molecular sieves, such as aluminosilicates and aluminophosphates, face limitations in molecular diffusion due to their microporous nature, which can adversely affect catalyst lifetime, activity, or selectivity in catalytic processes.
Innovation Solution
Development of hierarchical metallophosphates with a unique pore structure characterized by at least 75% micropore surface area and a hierarchy factor of at least 0.09, synthesized without the use of pore-forming agents, ensuring high microporosity combined with sufficient mesoporosity for enhanced diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If molecular sieves are made highly microporous to maintain structure and selectivity, then catalytic selectivity is improved, but molecular diffusion is restricted and catalyst activity decreases
Solution Approach 1:
The pore structure is segmented into multiple hierarchical levels (micropores, mesopores, and macropores) within the same material. Micropores ( <20 Å) provide selectivity through precise size exclusion, while mesopores (20-450 Å) and macropores (>450 Å) provide diffusion pathways. This segmentation allows different pore sizes to perform different functions simultaneously, resolving the contradiction between selectivity and activity.
Solution Approach 2:
The patent introduces a hierarchical pore structure that adds dimensional complexity to the traditional uniform microporous structure. By creating multiple pore size distributions across different dimensional scales, the material achieves both high selectivity (from micropores) and high diffusion rates (from mesopores and macropores), thereby improving both catalytic selectivity and activity.
2Productivity
If pore size is increased to enhance molecular diffusion, then catalyst activity is improved, but micropore surface area is reduced and selectivity deteriorates
Solution Approach 1:
The total pore volume is segmented into micropores, mesopores, and macropores with distinct size ranges. Micropores (<20 Å) maintain for selectivity, while mesopores (20-450 Å) and macropores (>450 Å) provide diffusion pathways. This segmentation allows the material to simultaneously achieve high selectivity from micropores and high activity from larger pores.
Solution Approach 2:
Different regions of the material have different pore structures optimized for specific functions. Microporous regions provide selectivity for specific molecular sizes, while mesoporous and macroporous regions provide enhanced diffusion pathways. This local differentiation of pore quality allows the material to optimize both selectivity and activity without compromise.
3Productivity
If hierarchical pore structure is created to improve diffusion, then catalyst activity is enhanced, but material complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The hierarchical pore structure is formed during the synthesis process itself rather than as a post-processing modification. Structure-directing agents are incorporated into the synthesis mixture to guide the formation of micropores, mesopores, and macropores simultaneously. This preliminary action during synthesis avoids complex post-processing steps and simplifies manufacturing while achieving the desired hierarchical structure.
Solution Approach 2:
The synthesis parameters (temperature, time, pH, composition ratios) are optimized to control the formation of different pore sizes during the single synthesis process. By carefully adjusting these parameters, the material achieves a controlled hierarchical pore structure with appropriate proportions of micropores, mesopores, and macropores, reducing the need for complex multi-step processing.
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 hierarchical metallophosphates exhibit superior catalytic performance in hydroisomerization processes by maintaining high microporosity while allowing for better molecular diffusion, thus enhancing catalyst activity and selectivity.
Implementation Method 1
The hierarchical metallophosphates exhibit superior catalytic performance in hydroisomerization processes
Implementation Method 2
allowing for better molecular diffusion
Data Source
AI summary
This invention relates to a novel family of hierarchical metallophosphates which are represented by the empirical formula:Rr+Mm2+EPxSiyOzwhere M is a divalent framework metal such as magnesium or zinc, R is an organoammonium cation, E is a trivalent framework element such as aluminum or gallium, and in which the hierarchical metallophosphates possess a pore structure having at least 75% of its total surface area being micropore surface area and a hierarchy factor of at least 0.09, said hierarchy factor defined as [(Vmicro/Vtot)*(Smeso/Stot)], where Vmicro and Vtot represent the micropore volume and total pore volume below 450 Å, respectively, and Smeso and Stot represent the non-micropore surface area and total surface area, respectively. The hierarchical metallophosphates of the invention are of use in hydrocarbon conversion processes such as hydroisomerization or dewaxing.