Rapid Cycle PSA Process Using Fast Kinetic CMS Adsorbents
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Solution Overview
Problem
Existing PSA processes face a trade-off between process productivity and product recovery, with efforts to increase productivity often detrimental to recovery, and vice versa, particularly when using carbon molecular sieve (CMS) adsorbents for separating O2 from N2 and/or Ar.
Innovation Solution
A rapid cycle pressure swing adsorption (PSA) process utilizing 'fast' kinetically selective CMS adsorbents with O2/N2 and O2/Ar kinetic selectivity of at least 5 and an O2 adsorption rate of at least 0.20, implemented in a process with a feed step duration of 60 seconds or less and 2 to 4 adsorption beds, maintaining high product recovery while enhancing productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If selective micro-pores are introduced to the adsorbent to increase kinetic selectivity, then oxygen/nitrogen or oxygen/argon selectivity is improved, but adsorption rate decreases
Solution Approach 1:
The patent changes the physical and chemical parameters of the CMS adsorbent by controlling carbonization temperature (500-900°C), heat treatment temperature (200-500°C), and hydrocarbon impregnation conditions to achieve the desired balance between pore size and adsorption kinetics. This allows optimization of both selectivity and rate simultaneously
Solution Approach 2:
The patent uses composite material structure combining CMS with specific pore modifiers and hydrocarbon treatments to create a hierarchical pore system that maintains high selectivity while improving overall adsorption rate through multiple transport pathways
2Productivity
If cycle time is reduced to increase productivity, then production from given material is improved, but working capacity per cycle decreases and pressure drop increases
Solution Approach 1:
The patent employs dynamic cycle optimization where feed step duration (0.1-10 seconds), pressure swing amplitude, and flow rates are dynamically adjusted based on real-time performance to maintain high productivity while preserving adequate working capacity. The system adapts operating parameters to balance rate and capacity
Solution Approach 2:
The patent uses periodic pressure swing cycles with optimized timing where adsorption, desorption, and regeneration phases are rhythmically coordinated. The periodic nature allows accumulation of product while maintaining high turnover rate through repeated cycles with optimal duration
3Productivity
If complex structured adsorbents with high void volume are used to increase productivity, then process throughput is improved, but product recovery decreases
Solution Approach 1:
The patent applies local quality enhancement by creating regions of high void volume for rapid mass transfer while maintaining regions of high density for strong adsorption. The CMS particles have heterogeneous pore distribution with micropores for selectivity and mesopores/macropores for transport, achieving both high throughput and high recovery locally and globally
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 process achieves improved process productivity while maintaining high product recovery, requiring less purge gas and optimizing cycle times to balance productivity and recovery, contrary to traditional CMS adsorbent limitations.
Implementation Method 1
The carbon molecular sieve (CMS) adsorbent is a 'fast' kinetically selective adsorbent... with an O2/N2 and/or O2/Ar kinetic selectivity of at least 5... Selective micro-pores are introduced to the adsorbent where the pore mouth controls kinetics of oxygen, nitrogen, or argon
Implementation Method 2
PSA processes have long been used in the separation of the components of air... carbon molecular sieve (CMS) adsorbents to separate varieties of gas mixtures... The rate of adsorption in CMS adsorbents is, therefore, inversely correlated with the kinetic selectivity
Implementation Method 3
rapid cycle pressure swing adsorption (PSA) process for separating O2 from N2 and/or Ar... subjecting each of the plurality of beds to a rapid PSA cycle comprising a feed step, at least one depressurization step, a purge step, and at least one re-pressurization step
Data Source
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AI summary
Disclosed herein are rapid cycle pressure swing adsorption (PSA) process for separating O2 from N2 and/or Ar. The processes use a carbon molecular sieve (CMS) adsorbent having an O2/N2 and/or O2/Ar kinetic selectivity of at least 5 and an O2 adsorption rate (1/s) of at least 0.2000 as determined by linear driving force model at 1 atma and 86 °F.