Fluidized Catalyst for Alkane Dehydrogenation
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Solution Overview
Problem
Current processes for dehydrogenating, dehydroaromatizing, and dehydrocyclizing alkanes and alkyl aromatic hydrocarbons face challenges in achieving high propylene yields without rapid catalyst deactivation due to coke deposition and active phase agglomeration, especially at elevated temperatures.
Innovation Solution
A process involving fluidized catalyst particles with Group 8-10 elements like Pt supported on a catalyst support, where the catalysts undergo cycles of hydrocarbon conversion, combustion to remove coke, and reduction to maintain activity and stability, allowing for efficient dehydrogenation and dehydroaromatization with improved propylene yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature of the dehydrogenation process is increased to increase conversion, then the propylene yield increases, but the catalyst particles deactivate rapidly due to coke deposition and agglomeration
Solution Approach 1:
The catalyst system is segmented into multiple functional components: Group 8-10 metal elements (Pt, Pd, Ni) dispersed on a support material. This segmentation allows different regions of the catalyst to perform different functions - the metal elements facilitate dehydrogenation while the support structure manages coke deposition and maintains stability at high temperatures.
Solution Approach 2:
The patent changes the operational parameters by conducting dehydrogenation at elevated temperatures (400-700°C) while maintaining controlled pressure conditions. This parameter change enables high propylene yield (up to 74% at 670°C) while the catalyst formulation compensates for thermal deactivation through its unique composition and structure.
2Reliability
If coke is removed by combustion using an oxygen-containing gas, then the catalyst activity is restored, but the agglomeration of the active phase is exacerbated, rapidly reducing the activity and stability of the catalyst particles
Solution Approach 1:
The patent converts the harmful effect of coke deposition into a beneficial process by implementing controlled combustion in a separate regenerator. The coke that would normally poison the catalyst is burned off in a dedicated zone, and the heat generated is used to regenerate the catalyst particles, transforming the harmful accumulation into a useful regeneration process.
Solution Approach 2:
The system is divided into separate functional zones: a conversion zone for dehydrogenation and a regenerator zone for coke removal. This segmentation allows the combustion process to occur in isolation from the active catalyst beds, preventing agglomeration while effectively removing coke.
3Productivity
If low pressure is used to achieve high propylene selectivity, then the propylene yield increases, but the process efficiency decreases
Solution Approach 1:
The patent optimizes the pressure parameter to operate at low absolute pressure (20-50 kPa) to maintain high propylene selectivity (up to 90%). This parameter change is combined with elevated temperature operation to achieve both high yield and acceptable process efficiency, as the endothermic dehydrogenation reaction is favored by lower pressure while the high temperature drives the equilibrium toward products.
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 process achieves sustained catalyst activity and stability over multiple cycles, significantly increasing propylene yields while minimizing catalyst deactivation, with propylene yields reaching up to 99% selectivity and maintaining performance for over 200 cycles.
Implementation Method 1
contacting a hydrocarbon-containing feed with fluidized catalyst particles that can include a Group 8-10 element disposed on a support within a conversion zone to effect one or more of dehydrogenation, dehydroaromatization, and dehydrocyclization
Implementation Method 2
contacting at least a portion of the coked catalyst particles in the first particle stream with an oxidant in a combustion zone to effect combustion of at least a portion of the coke
Implementation Method 3
contacting at least a portion of the regenerated catalyst particles with a reducing gas for a time period in a range from 1 second to less than 30 minutes to produce regenerated and reduced catalyst particles
Data Source
AI summary
Processes for upgrading a hydrocarbon. The process can include contacting a hydrocarbon-containing feed with fluidized catalyst particles that can include a Group 8-10 element or a compound thereof disposed on a support to effect one or more of dehydrogenation, dehydroaromatization, and dehydrocyclization of at least a portion of the hydrocarbon-containing feed to produce coked catalyst particles and an effluent. The process can also include contacting at least a portion of the coked catalyst particles with an oxidant to effect combustion of at least a portion of the coke to produce regenerated catalyst particles. The process can also include contacting at least a portion of the regenerated catalyst particles with a reducing gas to produce regenerated and reduced catalyst particles. The process can also include contacting an additional quantity of the hydrocarbon-containing feed with fluidized regenerated and reduced catalyst particles to produce additional effluent and re-coked catalyst particles.