ODH Complex with Integrated Oxygen Separation Module
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Solution Overview
Problem
Current oxidative dehydrogenation (ODH) processes for converting lower alkanes to alkenes face challenges such as high energy intensity, costly oxygen usage, and environmental concerns due to carbon dioxide emissions, with existing technologies not effectively integrating oxygen separation to recycle and reduce oxygen consumption.
Innovation Solution
A chemical complex that integrates an oxygen separation module with an ODH reactor system, utilizing a flooded gas mixer, heat exchanger, and caustic wash tower to recycle oxygen enriched gas back into the reaction, reducing oxygen consumption and carbon dioxide emissions, and employing specific catalysts and reactor configurations to enhance efficiency and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen is directly mixed with hydrocarbon feedstock to enable ODH reaction, then the ODH process can proceed, but the risk of catastrophic mixing and explosion increases
Solution Approach 1:
The system separates the oxygen supply into two independent streams: one stream provides oxygen to the ODH reactor through the oxygen-permeable membrane, while another stream directs unreacted oxygen to the oxygen separation module. This segmentation prevents direct mixing of large amounts of oxygen with hydrocarbon feedstock, reducing explosion risk while maintaining reaction efficiency.
Solution Approach 2:
An oxygen-permeable membrane acts as an intermediary between the oxygen source and the hydrocarbon feedstock. The membrane selectively transports oxygen to the reaction zone, enabling the ODH reaction to proceed while preventing direct contact between bulk oxygen and hydrocarbon, thereby ensuring process safety.
2Ease of operation
If conventional oxygen supply methods are used for ODH, then the process is simple to operate, but oxygen consumption is high and costs increase
Solution Approach 1:
The system implements a feedback loop where unreacted oxygen from the ODH reactor outlet is captured by the oxygen separation module, purified, and fed back to the reactor inlet. This closed-loop oxygen recycling reduces fresh oxygen consumption and operating costs while maintaining reaction performance.
Solution Approach 2:
Instead of discarding unreacted oxygen in the reactor effluent, the system recovers it through the oxygen separation module using a temperature-dependent oxygen transport membrane. The recovered oxygen is then reused in the ODH reaction, reducing material loss and operational expenses.
3Productivity
If high temperatures are used in steam cracking, then cracking reactions proceed efficiently, but energy consumption and equipment costs increase
Solution Approach 1:
The system changes the reaction parameters by conducting ODH at lower temperatures (below steam cracking temperatures) while maintaining high conversion efficiency through the use of oxygen-permeable membranes and selective catalysts. This parameter change reduces energy consumption and equipment requirements compared to conventional steam cracking.
Solution Approach 2:
The system replaces the high-temperature thermal cracking mechanism with a low-temperature catalytic oxidative dehydrogenation mechanism. This substitution enables the reaction to proceed at lower temperatures with higher selectivity, reducing energy input and equipment complexity.
4Loss of substance
If oxygen separation module is integrated with ODH reactor, then oxygen consumption is reduced, but device complexity increases
Solution Approach 1:
The oxygen separation module is integrated with the ODH reactor system by connecting the reactor outlet to the separation module inlet and the module outlet back to the reactor inlet. This merging of functions creates a compact oxygen recycling system that reduces overall complexity compared to separate standalone units while achieving significant oxygen conservation.
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 integrated system achieves high selectivity for alkenes with reduced oxygen usage and lower energy consumption, while capturing and recycling carbon dioxide, thereby improving economic efficiency and environmental sustainability of the ODH process.
Implementation Method 1
a) introducing a product stream comprising unreacted lower alkane and its corresponding alkene, unreacted oxygen and by-products into a reaction complex comprising an oxidative dehydrogenation reactor and an oxygen separation module comprising a temperature dependent oxygen-permeable membrane
Implementation Method 2
b) combusting said by-products to generate heat to raise temperature of said oxygen-permeable membrane to at least 850°C
Implementation Method 3
c) separating oxygen from said product stream across said oxygen-permeable membrane by introducing air into a retentate side of said membrane and producing an oxygen-enriched gas on a permeate side of the membrane
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Oxidative dehydrogenation is an alternative to the energy extensive steam cracking process presently used for the production of olefins from paraffins, but has not been implemented commercially partially due to the unstable nature of hydrocarbon/oxygen mixtures, and partially due to the cost involved in the construction of new facilities. An oxidative dehydrogenation chemical complex designed to reduce costs by including integration of an oxygen separation module that also addresses safety concerns and reduces emission of greenhouse gases is described.