Multi-Stage Alkane Dehydrogenation Catalyst Segmentation
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Solution Overview
Problem
Current processes for dehydrogenating, dehydroaromatization, and dehydrocyclization of alkanes and alkyl aromatic hydrocarbons face challenges in increasing propylene yield without catalyst deactivation, as higher temperatures lead to rapid coke deposition and agglomeration of active phases, reducing efficiency.
Innovation Solution
A multi-stage process involving two catalysts with Group 8-10 elements supported on various elements, where the first catalyst operates at a lower temperature to partially upgrade hydrocarbons, followed by a second catalyst at a higher temperature to further upgrade and regenerate the catalysts, maintaining activity and stability through coke combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature of the dehydrogenation process is increased to increase propylene yield, then the conversion efficiency is improved, but the catalyst particles deactivate rapidly due to coke deposition and agglomeration
Solution Approach 1:
The dehydrogenation process is divided into multiple sequential stages, each operating at different temperatures and using different catalysts. The first stage operates at lower temperature (560-650°C) with a first catalyst to achieve partial conversion, while the second stage operates at higher temperature (670-750°C) with a second catalyst to achieve final high yield. This segmentation allows each stage to operate within optimal conditions without causing rapid catalyst deactivation.
Solution Approach 2:
The invention changes the operating parameters (temperature, pressure, catalyst composition) between stages. The first stage uses moderate temperature and pressure conditions, while the second stage uses higher temperature and lower pressure conditions. This parameter optimization allows achieving high propylene yield (74% at 670°C, 100 kPa) without the catalyst deactivation problems that occur when operating continuously at high temperature.
2Productivity
If the pressure is reduced to increase dehydrogenation efficiency, then the propylene selectivity is improved, but the process becomes less economical due to complex pressure control requirements
Solution Approach 1:
The process is segmented into two stages with different pressure conditions. The first stage operates at moderate pressure (20-50 kPa absolute) to achieve good selectivity, while the second stage operates at higher pressure (100 kPa absolute) to simplify operation and reduce equipment complexity. This segmentation allows achieving high propylene selectivity without requiring the entire process to operate at complex low pressure conditions.
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 approach significantly increases propylene yield and selectivity, achieving higher efficiency by minimizing catalyst deactivation and maintaining catalyst activity over multiple cycles.
Implementation Method 1
contacting a hydrocarbon-containing feed with a first catalyst that can include a Group 8-10 element disposed on a support within a first conversion zone to effect one or more of dehydrogenation, dehydroaromatization, and dehydrocyclization
Implementation Method 2
contacting the first conversion zone effluent with a second catalyst that can include a Group 8-10 element disposed on a support within a second conversion zone to effect one or more of dehydrogenation, dehydroaromatization, and dehydrocyclization
Implementation Method 3
Coke can be removed by combustion using an oxygen-containing gas
Implementation Method 4
Coke can be removed by combustion using an oxygen-containing gas
Data Source
AI summary
Processes for upgrading a hydrocarbon. In some embodiments, the process can include contacting a hydrocarbon-containing feed with a first catalyst that can include a Group 8-10 element disposed on a support within a first conversion zone to effect dehydrogenation, dehydroaromatization, and/or dehydrocyclization of a portion of the feed to produce first conversion zone effluent that includes one or more upgraded hydrocarbons, molecular hydrogen, and unconverted feed. The process can also include contacting the first conversion zone effluent with a second catalyst that can include a Group 8-10 element disposed on a support within a second conversion zone to effect dehydrogenation, dehydroaromatization, and/or dehydrocyclization of at least a portion of the unconverted feed to produce a second conversion zone effluent that includes an additional quantity of upgraded hydrocarbon(s) and molecular hydrogen. A temperature of the second conversion zone effluent can be greater than a temperature of the first conversion zone effluent.