ODH Oxygenate Separation Using Cooling, Quench, and Caustic Recycle
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Solution Overview
Problem
Existing methods for converting lower alkanes to alkenes, such as steam cracking, are energy-intensive and can lead to coke formation, while oxidative dehydrogenation (ODH) processes produce by-products that require complex and energy-demanding additional processing.
Innovation Solution
A method and apparatus for oxidative dehydrogenation that includes an ODH reactor, cooling means, and a flash drum to separate alkenes from oxygenates and carbon-based oxides, utilizing a mixed metal oxide catalyst and controlled reaction conditions to produce and purify alkenes efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam cracking is used to convert lower alkanes to alkenes, then high alkene production is achieved, but energy consumption increases and coke formation occurs
Solution Approach 1:
The patent changes the fundamental reaction parameters by switching from high-temperature steam cracking (800°C+) to low-temperature oxidative dehydrogenation (300°C), thereby reducing energy consumption while maintaining alkene production. The reaction conditions are modified to use oxygen instead of steam as the reacting medium, fundamentally altering the energy profile of the process.
Solution Approach 2:
The patent applies oxidative dehydrogenation using oxygen as a strong oxidant to convert lower alkanes to alkenes. This approach accelerates the dehydrogenation reaction at lower temperatures compared to traditional steam cracking, reducing energy consumption while avoiding coke formation through controlled oxidation pathways.
2Use of energy by moving object
If oxidative dehydrogenation is used to convert lower alkanes to alkenes, then energy consumption is reduced, but by-products require complex additional processing
Solution Approach 1:
The patent extracts and removes by-products (oxygenates, carbon-based oxides, and water) from the ODH outlet stream through a series of separation units including condensers, flash drums, and absorbers. This extraction approach simplifies the overall process by selectively removing unwanted components while maintaining the low-energy advantage of ODH.
Solution Approach 2:
The patent segments the by-product removal process into distinct stages: condensation of oxygenates, separation of carbon-based oxides, and water removal. This segmentation allows each by-product type to be handled by specialized units optimized for its specific properties, reducing overall processing complexity compared to a single integrated separation system.
3Object-generated harmful factors
If oxidative dehydrogenation is used to convert lower alkanes to alkenes, then coke formation is reduced, but by-products are produced requiring additional processing
Solution Approach 1:
The patent converts the potential harm of oxidation (which could lead to complete combustion and COx formation) into a benefit by controlling the oxidation to produce oxygenates as intermediate products. These oxygenates are then easily condensed and removed, transforming what could be harmful over-oxidation into a useful separation opportunity that simplifies product purification.
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 reduces energy consumption and simplifies the purification process by effectively separating and condensing oxygenates, thereby enhancing the production of alkenes with reduced energy requirements.
Implementation Method 1
The ODH outlet stream is cooled and at least a portion of the oxygenate is condensed
Implementation Method 2
The alkene is separated from the oxygenate to produce an alkene outlet stream and an oxygenate outlet stream
Data Source
AI summary
A process, a system, and an apparatus are provided for converting a lower alkane to an alkene. Oxygen and the lower alkane are provided to an ODH reactor to convert at least a portion of the lower alkane to an alkene. An ODH stream comprising the alkene, an oxygenate, steam, and a carbon-based oxide is produced. The bulk of the oxygenate is removed from the ODH outlet stream by non-dilutive cooling, with residual oxygenate being removed using dilutive quenching with a carbonate. Subsequently, separation of the carbon-based oxide from the alkene is achieved using a caustic tower, which also produces spent caustic in the form of a carbonate, which is then used as the carbonate for dilutive quenching. Dilutive quenching using a carbonate allows conversion of the oxygenate to an acetate, which can then be used to simplify separation of the oxygenate from water.