Catalyst With Metallic Core And Eggshell Shell
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Solution Overview
Problem
Catalysts used in exothermic reactions face issues with thermal stress and deactivation due to uneven heat distribution, leading to reduced efficiency and increased costs, particularly in Fischer-Tropsch synthesis where high temperatures produce undesirable products like methane and soot.
Innovation Solution
A catalyst with a porous support surrounding a metallic core, such as copper wire, is developed, where the support is impregnated with active metals like cobalt and ruthenium, and a method involving a molten catalyst solution is used to concentrate the active metals near the surface, reducing heat buildup and thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If catalyst is located deep within the interior of the support, then catalyst loading is maximized, but temperature increases due to heat buildup causing deactivation and reduced efficiency
Solution Approach 1:
The patent applies local quality by creating an eggshell catalyst structure where the active metal catalyst is concentrated in a thin outer shell layer (typically 1-10 micrometers thick) rather than being uniformly distributed throughout the entire support particle. This localized placement ensures that the catalyst operates in the region with optimal temperature and mass transfer conditions, avoiding the thermal runaway problems that occur in the interior while maintaining high surface area for catalytic activity.
Solution Approach 2:
The patent segments the catalyst support structure into distinct functional zones: an inert inner core that provides mechanical strength and thermal stability, and an outer catalytic shell that contains the active metal. This segmentation allows each zone to perform its specific function optimally - the core manages heat and structural integrity while the shell provides catalytic activity with good mass transfer.
2Quantity of substance
If catalyst is located deep within the interior of the support, then catalyst loading is maximized, but thermal stress damages the support structure
Solution Approach 1:
The patent segments the catalyst support structure into distinct functional zones: an inert inner core that provides mechanical strength and thermal stability, and an outer catalytic shell that contains the active metal. This segmentation allows each zone to perform its specific function optimally - the core manages heat and structural integrity while the shell provides catalytic activity with good mass transfer.
Solution Approach 2:
The inner core acts as an intermediary thermal management element between the external environment and the catalytic shell. It absorbs and distributes thermal stress, preventing direct transmission of thermal shocks to the fragile catalytic layer and support structure, thereby maintaining structural integrity during exothermic reactions.
3Productivity
If eggshell or core-shell catalyst structure is used, then mass transport restrictions are reduced and C5+ selectivity increases, but catalyst loading decreases
Solution Approach 1:
The patent optimizes the thickness of the outer catalytic shell parameter to achieve the desired balance between mass transport efficiency and catalyst loading. By controlling the shell thickness to be in the range of 1-10 micrometers, the patent ensures sufficient catalytic activity while maintaining good mass transfer properties, thus achieving high C5+ selectivity without excessive loss of catalyst loading compared to conventional structures.
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
This configuration minimizes catalyst deactivation, reduces the need for active metal mass, and decreases the production of undesirable products by effectively managing temperature fluctuations, enhancing catalyst productivity and selectivity.
Implementation Method 1
Due to its high thermal capacity, the metal serves as a heat reservoir to either absorb or release heat according to the temperature in the outer layer where the reaction is occurring
Implementation Method 2
replaces the porous interior support with a solid material with high thermal conductivity and heat capacity
Implementation Method 3
The support is impregnated with an active metal catalyst, such as cobalt and/or ruthenium
Implementation Method 4
In the case of exothermic reactions, catalyst that is located deep within the interior of the support will be exposed to higher temperatures due to buildup of heat energy released by the reaction
Data Source
AI summary
Two different types of catalysts are disclosed. The first catalyst has a porous support that is impregnated with an active metal catalyst. The support surrounds a metallic core, which functions to increase the bulk heat capacity of the catalyst, thereby damping temperature swings during use. The second catalyst also has a porous support that is impregnated with an active metal catalyst, which is heterogeneously distributed so that the catalyst is concentrated at or near the surface of the support structure. This is accomplished by impregnating the catalyst by pouring a molten metal catalyst over the bulk catalyst supports. This method allows of a small volume of molten catalyst relative to the pore volume of the support and concentrates the catalyst in a band near the surface of the supports.