Copper-Exchanged Zeolites for Ethylene Separation

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Solution Overview

Problem

Current ethylene-ethane separation processes in polyethylene plants require large distillation towers and high energy consumption, making it difficult to recycle or recover stranded ethylene gas streams, and existing membrane technologies have limited selectivity for ethylene.

Innovation Solution

A pressure-swing adsorption process using zeolite adsorbent particles with CHA or ERI frameworks that alternates the input of feed gas between two beds to preferentially adsorb ethylene, reducing vacuum power consumption and eliminating the need for distillation, achieving high ethylene purity without thermal-driven separation processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If distillation processes are used to separate ethylene from ethane, then separation purity is improved, but energy consumption and device complexity increase

Engineering Contradiction:

Improveethylene purityVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the thermal distillation process with a pressure-swing adsorption process using zeolite beds. Instead of using thermal energy to separate ethylene from ethane, the invention uses pressure variations and adsorption/desorption cycles of zeolite material to achieve the same separation, thereby eliminating the need for large distillation towers and reducing energy consumption significantly

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the separation parameter from temperature-based (distillation) to pressure-based (adsorption). By varying pressure between high and low states in alternating zeolite beds, the system achieves ethylene/ethane separation without thermal input, transforming the separation mechanism from thermal-driven to pressure-driven

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If membrane technologies are used for ethylene separation, then energy consumption is reduced, but selectivity and separation purity deteriorate

Engineering Contradiction:

Improveenergy consumptionVSAvoidethylene purity

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent employs zeolite, a porous crystalline material with specific pore structures (CHA or ERI frameworks), as the adsorbent medium. The porous structure provides selective adsorption sites that preferentially capture ethylene over ethane and other impurities, achieving high selectivity and purity that membrane technologies cannot attain while maintaining low energy consumption

Inventive Principle:

Principle #31Porous materials

3Manufacturing precision

If PSA technology is used to recover stranded ethylene, then ethylene purity is improved, but vacuum power consumption increases

Engineering Contradiction:

Improveethylene purityVSAvoidvacuum power consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The invention uses periodic pressure variations in alternating zeolite beds to achieve continuous ethylene recovery. During one bed's desorption phase, the other bed is in adsorption mode, and vice versa. This periodic switching eliminates the need for continuous vacuum application, reducing vacuum power consumption while maintaining high ethylene purity through the cyclic adsorption-desorption process

Inventive Principle:

Principle #19Periodic action

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 effectively separates ethylene from impurities like nitrogen, hydrogen, ethane, propane, and isobutane, achieving ethylene purity of at least 98% with reduced energy consumption, enabling the recovery of stranded ethylene gases in polyethylene plants.

Implementation Method 1

The contact occurs at a feed pressure of from about 50 to about 500 psia for a sufficient period of time to preferentially adsorb ethylene over other impurities in the gas stream

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

A pressure-swing adsorption process using zeolite adsorbent particles with CHA or ERI frameworks that alternates the input of feed gas between two beds to preferentially adsorb ethylene

Methodology Applied

Scientific EffectPressure-swing adsorption: Pressure Swing Adsorption

Implementation Method 3

The tail gas stream is removed by depressurization of the bed and desorption of ethylene adsorbed on the zeolite adsorbent

Methodology Applied

Scientific EffectDesorption: Desorption

Data Source

PatentUS11554344B2Copper (II)-exchanged small-pore zeolites for improved ethylene separation over ethane

Publication Date: 2023.01.17 CHEVRON USA INC

AI summary

The present invention and embodiments thereof provide a process to separate ethylene products from impurities such as nitrogen, hydrogen, ethane, propane and isobutane without the need for distillation processes.