C8 Aromatic Isomerization Catalyst Protection via Hydrogen Co-feeding
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Solution Overview
Problem
Liquid-phase isomerization catalysts in p-xylene production processes experience rapid deactivation at high weight hourly space velocities (WHSV), leading to reduced catalyst service life and increased costs for regeneration and replacement.
Innovation Solution
Co-feeding molecular hydrogen at a high rate of at least 100 ppm with the C8 aromatic hydrocarbon feed into an isomerization reactor, where the catalyst is maintained in a liquid phase under specific pressure and temperature conditions, significantly reduces catalyst deactivation even at high WHSVs of up to 20 hour−1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid-phase isomerization is operated at high weight hourly space velocities to increase productivity, then p-xylene production efficiency is improved, but catalyst deactivation rate increases rapidly
Solution Approach 1:
The patent applies parameter changes by modifying the chemical environment parameters (adding molecular hydrogen at specific concentrations, adjusting temperature and pressure parameters) to create optimal conditions that allow high WHSV operation while protecting catalyst stability. This resolves the contradiction by changing operational parameters to simultaneously achieve high productivity and catalyst longevity.
Solution Approach 2:
The patent introduces molecular hydrogen as an intermediary substance that mediates between the feedstock and catalyst. The hydrogen acts as a protective intermediary that prevents direct harmful interactions between the hydrocarbon feed and catalyst active sites, thereby extending catalyst life while maintaining high conversion rates at elevated WHSV.
2Productivity
If liquid-phase isomerization is operated at high weight hourly space velocities to increase productivity, then processing speed is improved, but catalyst deactivation accelerates leading to increased regeneration and replacement costs
Solution Approach 1:
The patent applies preliminary action by pre-introducing molecular hydrogen into the reaction system before significant catalyst deactivation occurs. This proactive measure prevents rapid deactivation pathways from initiating, thereby extending catalyst service life and reducing the frequency of regeneration cycles while maintaining high processing speeds.
Solution Approach 2:
The patent implements beforehand cushioning by creating a protective hydrogen-rich environment that cushions the catalyst against deactivating effects. This preparatory protective measure allows the catalyst to withstand high WHSV conditions without rapid deactivation, thereby reducing regeneration frequency and associated downtime.
3Duration of action of stationary object
If molecular hydrogen is co-fed at high rates to reduce catalyst deactivation, then catalyst service life is extended, but process complexity and hydrogen consumption increase
Solution Approach 1:
The patent applies partial action by introducing molecular hydrogen at optimized concentrations (not excessive amounts) that are sufficient to provide protective effects and extend catalyst life, while avoiding the drawbacks of excessive hydrogen addition such as unnecessary complexity and increased consumption. This balanced approach achieves catalyst protection with minimal additional process 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 extends the catalyst service life, reduces costs, and maintains high p-xylene production efficiency by minimizing catalyst deactivation, allowing for efficient operation at higher WHSVs without significant loss in p-xylene concentration.
Implementation Method 1
Co-feeding molecular hydrogen at a high rate of at least 100 ppm with the C8 aromatic hydrocarbon feed into an isomerization reactor
Implementation Method 2
contacting the molecular hydrogen and the C8 aromatic hydrocarbons with the isomerization catalyst under isomerization conditions in the isomerization reactor
Data Source
AI summary
A liquid phase isomerization process comprising cofeeding molecular hydrogen at a feeding rate ≥100 ppm by weight can effectively convert a C8 aromatic hydrocarbon isomerization feed in the presence of an isomerization catalyst with a very low deactivation rate of the catalyst, even at high WHSV ≥5 hour−1.