Catalyst Gas Distribution for Hydrothermal Damage Reduction
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Solution Overview
Problem
Hydrocarbon catalysts used in dehydrocyclodimerization processes face deactivation due to hydrothermal dealumination and coke formation, particularly when exposed to high temperatures and hydrogen, leading to reduced effectiveness and irreversible loss of activity.
Innovation Solution
A process involving a gas stream distribution system where the gas is fed into the center of a downwardly flowing catalyst stream, allowing for thorough contact and drying, followed by separate zones for drying and reduction to minimize hydrothermal damage and maintain catalyst activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature is used for reduction, then reduction effectiveness is improved, but hydrothermal dealumination increases causing catalyst deactivation
Solution Approach 1:
The reduction process is divided into two separate zones: a drying zone operating at lower temperature to remove water, and a reduction zone operating at higher temperature to reduce metal oxides. This spatial segmentation allows each zone to operate at optimal temperature without the harmful effects of combining both functions at high temperature, thus preventing hydrothermal dealumination while maintaining reduction effectiveness.
Solution Approach 2:
The drying zone performs water removal before the catalyst enters the high-temperature reduction zone. By preliminarily removing water at lower temperature, the catalyst is protected from hydrothermal dealumination when subsequently exposed to high temperature for reduction, thereby maintaining catalyst structure and activity.
2Manufacturing precision
If gas stream is fed from side inlet, then gas distribution is improved, but catalyst residence time increases causing hydrogen damage
Solution Approach 1:
Instead of feeding gas from the side as in conventional designs, the gas stream is fed from the center of the catalyst bed and flows upward against the downward-moving catalyst. This inverted flow configuration improves gas distribution through the catalyst while reducing catalyst residence time in the hydrogen atmosphere, thereby preventing hydrogen-induced deactivation.
3Productivity
If thorough contact between gas and catalyst is ensured, then conversion efficiency is improved, but catalyst exposure to harmful conditions increases
Solution Approach 1:
The reactor is segmented into distinct functional zones: a drying zone for water removal and a reduction zone for metal oxide reduction. This segmentation allows thorough gas-catalyst contact in each zone for efficient processing, while limiting overall catalyst exposure to harmful high-temperature water vapor conditions that cause deactivation.
Solution Approach 2:
Different zones are assigned different temperature and atmospheric conditions optimized for their specific function. The drying zone operates at lower temperature with water removal, while the reduction zone operates at higher temperature with dry hydrogen atmosphere. This local quality differentiation ensures efficient conversion while protecting catalyst integrity in each respective zone.
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 effectively reduces hydrothermal damage and maintains catalyst activity by ensuring thorough gas distribution without excessive catalyst residence time, allowing for efficient reuse of the catalyst.
Implementation Method 1
The propensity of zeolitic materials to dealuminate increases as water concentration and temperature increase. Sources of water include desorption of water on the catalyst coming from the oxidative regeneration section
Implementation Method 2
Sources of water include desorption of water on the catalyst coming from the oxidative regeneration section
Implementation Method 3
the catalyst must be reduced before entering the dehydrocyclodimerization reactor by contact with hydrogen gas to reduce the metals on the catalyst
Data Source
AI summary
A process and apparatus is disclosed for distributing a gas stream into a downwardly flowing catalyst stream in a vessel by feeding the gas stream into a center of the vessel or the catalyst stream into a hollow cap. The gas stream enters the cap and exits the cap flowing upwardly to contact the catalyst stream.