Feed Purification in Ethane Oxidative Dehydrogenation
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Solution Overview
Problem
Impurities in the feed stream for oxidative dehydrogenation of ethane accumulate on catalyst surfaces, affecting ethane conversion and ethylene yield, and existing methods do not effectively address premature catalyst deactivation and cost savings in the process.
Innovation Solution
A process involving a purification unit with a first oxidative dehydrogenation catalyst to reduce impurity concentrations, followed by an oxidative dehydrogenation unit with a second catalyst at a higher temperature, using a system that includes regeneration of catalysts with acetic acid and recycling of acetic acid to maintain process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a purification unit with first oxidative dehydrogenation catalyst is added to remove impurities before the main reaction, then catalyst deactivation is prevented and ethylene yield is improved, but device complexity and process steps increase
Solution Approach 1:
The patent combines the purification function and oxidative dehydrogenation function into a single integrated catalyst system. The first oxidative dehydrogenation catalyst performs both impurity removal and ethane conversion functions, eliminating the need for separate purification units while maintaining catalyst reliability and activity.
Solution Approach 2:
The first oxidative dehydrogenation catalyst is designed with multi-functionality to simultaneously remove impurities from the feed stream and convert ethane to ethylene. This universal catalyst approach reduces process complexity by consolidating multiple functions into one catalyst system.
2Productivity
If feed stream is purified to remove impurities like boron, sodium, and green oil, then ethane conversion is improved, but additional process steps and equipment are required
Solution Approach 1:
The patent merges the purification step and oxidative dehydrogenation step into a single reaction step using the first oxidative dehydrogenation catalyst. This catalyst simultaneously removes impurities such as boron, sodium, and green oil while converting ethane to ethylene, thereby improving ethane conversion without adding separate purification process steps.
3Loss of substance
If spent catalysts are regenerated using acetic acid and reused, then cost savings are achieved and waste is reduced, but additional regeneration equipment and process steps are needed
Solution Approach 1:
The patent implements a catalyst regeneration system where spent oxidative dehydrogenation catalysts are recovered and regenerated using acetic acid treatment. The regenerated catalysts are then reused in the oxidative dehydrogenation process, reducing catalyst waste and achieving cost savings while managing the complexity through systematic regeneration procedures.
Solution Approach 2:
The regeneration process uses acetic acid, which is already present in the product stream from the oxidative dehydrogenation reaction. This creates a self-service system where a byproduct of the main reaction is utilized to regenerate the catalyst, reducing the need for external regeneration agents and minimizing additional equipment requirements.
4Productivity
If higher temperature is used in oxidative dehydrogenation unit, then ethylene production rate increases, but energy consumption and risk of side reactions increase
Solution Approach 1:
The patent applies preliminary action by removing impurities through the first oxidative dehydrogenation catalyst before the main high-temperature oxidative dehydrogenation reaction. This pre-purification prevents catalyst deactivation and side reactions, allowing the second catalyst to operate at optimal temperatures for maximum ethylene production rate while minimizing energy consumption and unwanted byproduct formation.
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 impurity levels, prevents catalyst deactivation, and enables cost savings by reusing spent catalysts, thereby enhancing ethane conversion and ethylene yield while maintaining process efficiency.
Implementation Method 1
The feed stream is contacted with the first oxidative dehydrogenation catalyst at a first temperature to reduce a concentration of impurities in the feed stream
Implementation Method 2
oxidative dehydrogenation of ethane involves the endothermic removal of hydrogen from ethane and the exothermic oxidation of hydrogen
Implementation Method 3
The purified feed stream is contacted with the second oxidative dehydrogenation catalyst at a second temperature greater than the first temperature to dehydrogenate ethane to produce a product stream that includes ethylene
Implementation Method 4
oxidative dehydrogenation of ethane is a way of converting ethane, which is relatively inert, into ethylene, which is more reactive
Implementation Method 5
regenerating the second portion of the first oxidative dehydrogenation catalyst includes contacting the second portion of the first oxidative dehydrogenation catalyst with acetic acid
Data Source
AI summary
A feed stream including ethane is flowed to a purification unit that includes a first oxidative dehydrogenation catalyst. The feed stream is contacted with the first oxidative dehydrogenation catalyst at a first temperature to reduce a concentration of impurities in the feed stream to produce a purified feed stream. The purified feed stream is flowed to an oxidative dehydrogenation unit that includes a second oxidative dehydrogenation catalyst. The purified feed stream is contacted with the second oxidative dehydrogenation catalyst in the presence of oxygen at a second temperature greater than the first temperature to dehydrogenate ethane to produce a product stream that includes ethylene.