Aromatization Catalyst Regeneration via Sequential Chlorination and Decoking
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Solution Overview
Problem
Spent catalysts used in aromatization processes, containing transition metals like platinum, lose activity over time, leading to reduced selectivity and conversion rates, necessitating effective regeneration methods to restore their performance without causing corrosion in metal reactors.
Innovation Solution
A method involving chlorination with a chlorine-containing stream, followed by a chlorine purging step using an inert gas, decoking with an oxygen-containing stream, and subsequent fluorination with a fluorine-containing stream to regenerate the catalyst, specifically designed for use in metal reactors like stainless steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spent catalyst is treated with halogenation followed by decoking to restore activity, then catalyst activity and selectivity are improved, but corrosion of metal reactor occurs
Solution Approach 1:
The regeneration process is divided into distinct sequential stages: chlorination step, chlorine purging step, decoking step, and fluorination step. Each step performs a specific function and prepares the catalyst for the next step, allowing controlled restoration of catalyst activity while managing corrosion risks at each stage separately
Solution Approach 2:
The chlorination step is performed before decoking to modify the catalyst surface and deactivate carbon deposits, making them more susceptible to removal. The chlorine purging step is performed beforehand to remove excess chlorine and prevent excessive corrosion during subsequent decoking and fluorination steps
2Reliability
If multiple halogenation steps are used to rejuvenate catalyst, then catalyst performance is restored, but process complexity increases
Solution Approach 1:
The complex regeneration process is segmented into four distinct steps with clear boundaries and transition criteria. Each step has specific operational parameters and duration, making the overall complex process manageable and controllable through systematic progression
Solution Approach 2:
Each step involves controlled changes in chemical environment (chlorine-containing atmosphere, oxygen-containing atmosphere, fluorine-containing atmosphere) and operational parameters (temperature, time, gas flow rates), allowing precise control over the regeneration process to achieve desired catalyst performance
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 method effectively restores the catalyst's activity and selectivity, reducing corrosivity in metal reactors and maintaining performance comparable to fresh catalysts, with low fouling rates and minimal iron contamination.
Implementation Method 1
contacting the spent catalyst with a chlorine-containing stream comprising a chlorine-containing compound to produce a chlorinated spent catalyst
Implementation Method 2
contacting the chlorinated spent catalyst with a decoking gas stream comprising oxygen to produce a de-coked catalyst
Implementation Method 3
contacting the de-coked catalyst with a fluorine-containing stream comprising a fluorine-containing compound
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
Methods for regenerating a spent catalyst in a metal reactor are disclosed. Such methods may employ a step of chlorinating the spent catalyst, followed by decoking the chlorinated spent catalyst, and then fluorinating the de-coked catalyst.