Ammonia Sweep Gas Membrane Reactor for Low-Complexity H2 Separation

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Solution Overview

Problem

Existing ammonia cracking processes for hydrogen production are inefficient and require significant infrastructure and materials, leading to high energy consumption, corrosion issues, and complex systems due to the use of steam or nitrogen as sweep gases.

Innovation Solution

Utilizing ammonia as a sweep gas in a membrane reactor, which allows for continuous recycling and reduces the need for additional infrastructure, simplifies the system, and minimizes corrosion by avoiding steam, while achieving high conversion rates of ammonia to hydrogen and nitrogen.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If steam or nitrogen is used as sweep gas, then hydrogen permeation is enhanced, but system complexity and infrastructure requirements increase

Engineering Contradiction:

Improvehydrogen permeation rateVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system uses ammonia from the retentate side to serve as the sweep gas on the permeate side, eliminating the need for external steam generation infrastructure or nitrogen supply systems. The ammonia is separated and recycled back to the retentate side, creating a self-sufficient loop that reduces overall system complexity while maintaining high hydrogen permeation rates.

Inventive Principle:

Principle #25Self-service

2Productivity

If steam is used as sweep gas, then hydrogen permeation is enhanced, but corrosion issues arise

Engineering Contradiction:

Improvehydrogen permeation rateVSAvoidcorrosion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention replaces steam (which causes corrosion) with ammonia as the sweep gas. Ammonia serves the same function of maintaining low hydrogen partial pressure on the permeate side while avoiding the corrosive problems associated with steam. The ammonia is then separated and recycled, converting a harmful substance (steam) into a beneficial non-corrosive alternative (ammonia).

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If additional sweep gas infrastructure is used, then hydrogen production efficiency improves, but material usage and costs increase

Engineering Contradiction:

Improvehydrogen production efficiencyVSAvoidmaterial usage

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

Instead of discarding the ammonia that crosses over to the permeate side as waste, the system recovers and separates it, then recycles it back to the retentate side as the sweep gas. This recovery process eliminates the need for continuous material consumption and external infrastructure, reducing both material usage and system costs while maintaining high hydrogen production efficiency.

Inventive Principle:

Principle #34Discarding and recovering

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 enhances energy efficiency, reduces greenhouse gas emissions, and decreases system complexity and costs by leveraging ammonia's recyclability and avoiding corrosive environments, thus improving scalability and infrastructure requirements.

Implementation Method 1

hydrogen is separated from the nitrogen and unreacted ammonia by passing the hydrogen through a hydrogen-permeable membrane

Methodology Applied

Scientific EffectPermeation: Permeation

Implementation Method 2

The difference in partial pressure of hydrogen between the retentate side of the membrane and the permeate side of the membrane drives the permeation of hydrogen through the membrane

Methodology Applied

Scientific EffectPartial pressure difference: Pressure Gradient

Implementation Method 3

Ammonia cracking to form hydrogen and nitrogen is a highly endothermic process, favored at higher temperatures and lower pressures

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 4

Ammonia cracking to form hydrogen and nitrogen is a highly endothermic process

Methodology Applied

Scientific EffectEndothermic reaction: Endothermic Reaction

Implementation Method 5

passing a gas (referred to as a sweep gas) along the permeate side of the membrane to reduce the partial pressure of hydrogen on the permeate side

Methodology Applied

Scientific EffectGas flow: Convection

Implementation Method 6

The ammonia sweep gas can be separated from the permeated hydrogen and continuously recycled

Methodology Applied

Scientific EffectGas separation: Distillation

Data Source

PatentUS12492121B2Conversion of ammonia to hydrogen and nitrogen using ammonia as a sweep gas

Publication Date: 2025.12.09 SAUDI ARABIAN OIL CO

AI summary

The disclosure relates to systems and methods for the production of hydrogen (H2) from ammonia (NH3) in a membrane reactor that include using ammonia as a sweep gas. Ammonia is converted to hydrogen and nitrogen (N2), and the hydrogen is separated from the nitrogen and unreacted ammonia by passing the hydrogen through a hydrogen-permeable membrane while using ammonia as a sweep gas. The ammonia sweep gas can be separated from the permeated hydrogen and continuously recycled.