Group 8-10 Catalyst Dehydrogenation Cycle for Propylene Yield
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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 agglomeration, especially at elevated temperatures.
Innovation Solution
A process involving a Group 8-10 element, such as Pt, disposed on a support, which undergoes cycles of dehydrogenation, combustion to remove coke, and reduction to maintain catalyst activity and stability, allowing for efficient dehydrogenation of alkanes and alkyl aromatics at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature of the dehydrogenation process is increased to improve propylene yield, then the conversion and equilibrium yield increase, but the catalyst deactivates rapidly due to coke deposition and agglomeration
Solution Approach 1:
The patent implements periodic catalyst regeneration cycles where the catalyst is alternately used for dehydrogenation and then regenerated by controlled combustion. This periodic action allows the catalyst to maintain high activity over extended periods by removing accumulated coke deposits at regulated intervals, thereby resolving the contradiction between maintaining high propylene yield and preventing rapid catalyst deactivation
Solution Approach 2:
The patent carefully controls the regeneration conditions by limiting the oxygen partial pressure to 0.01-10 atm and temperature to 300-900°C, and controlling the hydrocarbon partial pressure during dehydrogenation to 0.02-10 atm. These parameter changes allow the process to achieve high propylene yields while preventing the severe coke deposition and metal agglomeration that would otherwise cause rapid catalyst deactivation
2Manufacturing precision
If low pressure is used to achieve high propylene selectivity, then the dehydrogenation efficiency improves, but the process complexity and operational constraints increase
Solution Approach 1:
The patent employs parameter changes by controlling the hydrocarbon partial pressure within a specific range (0.02-10 atm) rather than requiring extremely low pressures. This approach maintains high propylene selectivity while simplifying the process equipment and operational requirements, thereby resolving the contradiction between manufacturing precision and device complexity
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 stable catalyst performance over multiple cycles with high propylene yields, exceeding 90% selectivity and maintaining activity for extended periods, even at high temperatures, without the need for halogen addition.
Implementation Method 1
contacting a hydrocarbon-containing feed with a catalyst that can include a Group 8-10 element disposed on a support to effect one or more of dehydrogenation, dehydroaromatization, and dehydrocyclization
Implementation Method 2
contacting at least a portion of the coked catalyst with an oxidant to effect combustion of at least a portion of the coke
Implementation Method 3
contacting at least a portion of the regenerated catalyst with a reducing gas to produce a regenerated and reduced catalyst
Data Source
AI summary
Processes for upgrading a hydrocarbon. The process can include (I) contacting a hydrocarbon-containing feed with a catalyst that can include a Group 8-10 element or a compound thereof disposed on a support to effect conversion of the hydrocarbon-containing feed to produce a coked catalyst and an effluent. The process can also include (II) contacting the coked catalyst with an oxidant to effect combustion the coke to produce a regenerated catalyst. The process can also include (IIa) contacting the regenerated catalyst with a reducing gas to produce a regenerated and reduced catalyst. The process can also include (III) contacting an additional quantity of the hydrocarbon-containing feed with the regenerated and reduced catalyst. A cycle time from the contacting the hydrocarbon-containing feed with the catalyst in step (I) to the contacting the additional hydrocarbon-containing feed with the regenerated and reduced catalyst in step (III) can be ≤1 hours.