Pressure Swing Adsorption for Olefin Separation in Methane Oxidative Coupling
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Solution Overview
Problem
The modern refining and petrochemical industry faces challenges with energy-intensive and costly cryogenic distillation methods for separating hydrocarbons, particularly in oxidative coupling of methane (OCM) processes, which require more efficient and cost-effective non-cryogenic separation techniques.
Innovation Solution
The use of pressure swing adsorption (PSA) systems with metal organic frameworks (MOFs) and zeolites to separate and recover olefins, such as ethylene and propylene, from hydrocarbon streams, including those from OCM reactors, by adsorbing and desorbing gases at different pressures, enhancing the separation efficiency and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cryogenic distillation is used to separate hydrocarbons, then separation efficiency is improved, but energy consumption and operational cost increase
Solution Approach 1:
The patent changes the operating parameters from cryogenic temperatures to ambient or elevated temperatures, and from pressure-based distillation to adsorption-based separation. This parameter change enables effective separation without requiring the high energy input of cryogenic distillation, directly resolving the contradiction between separation efficiency and energy consumption
Solution Approach 2:
The patent replaces the mechanical/thermal system of cryogenic distillation with a chemical adsorption system using selective adsorbents. This substitution eliminates the need for energy-intensive cooling and heating processes while achieving comparable or superior separation efficiency through molecular-level interactions between adsorbents and hydrocarbons
2Measurement precision
If conventional fractionation technology is used, then hydrocarbon separation is achieved, but installation and operational costs increase
Solution Approach 1:
The patent employs adsorbents that can be regenerated and reused, replacing expensive, complex cryogenic distillation equipment with simpler, more cost-effective adsorption units. The adsorbent materials, while consumable, are significantly cheaper to install and operate than conventional fractionation equipment, directly addressing the cost contradiction
Solution Approach 2:
By changing from high-pressure, high-temperature cryogenic operations to ambient temperature adsorption processes, the patent reduces capital expenditure on equipment and operational expenses on energy consumption, making the technology more economically viable while maintaining separation capability
3Use of energy by moving object
If pressure swing adsorption is used to separate olefins, then energy consumption is reduced, but separation purity may be compromised
Solution Approach 1:
The patent employs selective adsorbents with specific molecular structures and surface properties that are locally optimized for interacting with particular hydrocarbon molecules. This local quality at the molecular level enables high separation purity even at ambient temperatures, resolving the contradiction between energy savings and purity maintenance
Solution Approach 2:
The patent utilizes composite adsorbent materials combining multiple functional components to achieve both high selectivity for target olefins and effective rejection of impurities. These composite materials enable superior separation purity under low-energy conditions, directly addressing the purity-energy contradiction
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 enables the effective separation and recovery of desired hydrocarbons with high purity, reduces energy costs, and improves carbon efficiency by enriching olefins by factors of up to 20 or more, while minimizing the carbon footprint of OCM processes.
Implementation Method 1
directing a gas mixture comprising at least one impurity and a product gas into a pressure swing adsorption (PSA) vessel containing an adsorbent to adsorb the product gas on the adsorbent
Implementation Method 2
The use of pressure swing adsorption (PSA) systems with metal organic frameworks (MOFs) and zeolites to separate and recover olefins, such as ethylene and propylene, from hydrocarbon streams
Data Source
AI summary
The present disclosure provides a method for generating higher hydrocarbon(s) from a stream comprising compounds with two or more carbon atoms (C2+), comprising introducing methane and an oxidant (e.g., O2) into an oxidative coupling of methane (OCM) reactor. The OCM reactor reacts the methane with the oxidant to generate a first product stream comprising the C2+ compounds. The first product stream can then be directed to a separations unit that recovers at least a portion of the C2+ compounds from the first product stream to yield a second product stream comprising the at least the portion of the C2+ compounds.