Catalyst Regeneration via Three-Stage De-Coking
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Solution Overview
Problem
The yield of propylene decreases over time due to catalyst coking in the process of forming propylene from butene, requiring an effective regeneration method to restore catalyst activity without degrading the catalytic structure.
Innovation Solution
A de-coking treatment process involving three consecutive temperature and oxygen concentration conditions is applied to the catalyst system, comprising a metathesis catalyst with tungsten oxide and silica and a cracking catalyst with ZSM-5 zeolite, to burn off coke and produce carbon monoxide, eliminating the need for supplemental reducing agents like hydrogen or NO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the catalyst system is used continuously to form propylene from butene, then propylene production increases, but the catalyst becomes coked and propylene yield decreases over time
Solution Approach 1:
The patent implements periodic regeneration cycles where the catalyst is alternately used for propylene production and then regenerated by burning off coke deposits. This periodic switching between production and regeneration modes maintains catalyst activity over extended operation periods, resolving the contradiction between continuous production and catalyst reliability.
Solution Approach 2:
The patent recovers catalyst activity by burning off accumulated coke deposits during regeneration cycles. Instead of discarding the catalyst after deactivation, the system recovers it through controlled oxidation of coke, allowing the catalyst to be reused for additional production cycles.
2Reliability
If traditional regeneration methods using supplemental reducing agents are employed, then catalyst reduction is achieved, but process complexity and cost increase due to additional chemicals
Solution Approach 1:
The patent enables the catalyst to self-reduce during the regeneration process by utilizing carbon monoxide generated in-situ from coke combustion. The CO produced during coke burning automatically reduces the metal oxide catalyst without requiring external reducing agents, simplifying the regeneration system and eliminating the need for supplemental reducing chemicals.
Solution Approach 2:
The patent converts the harmful coke deposits that deactivate the catalyst into a beneficial reducing agent (carbon monoxide). The CO generated from coke combustion is utilized to reduce the metal oxide catalyst, transforming what was previously a waste product requiring removal into a useful chemical that restores catalyst activity.
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 regeneration process effectively increases propylene yield by removing coke from the catalyst system, maintaining catalytic stability and eliminating the need for additional reducing agents, thereby enhancing propylene production efficiency.
Implementation Method 1
The treatment conditions may promote the formation of carbon monoxide when coke is burned in the regeneration
Implementation Method 2
CO may be utilized for metal reduction on the metathesis catalyst system
Data Source
AI summary
A catalyst system may be regenerated by a method that includes exposing the catalyst system to a de-coking treatment. The de-coking treatment may include three consecutive treatment conditions including a first treatment condition, a second treatment condition, and a third treatment condition. The catalyst system may include a metathesis catalyst and a cracking catalyst. The metathesis catalyst may include tungsten oxide and silica carrier, and the cracking catalyst may include ZSM-5 zeolite.