Ammonia Cracking Bed with In-Situ Nitrogen Separation
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Solution Overview
Problem
Conventional ammonia decomposition processes for hydrogen and nitrogen separation are inefficient due to complex separation steps, hindering widespread industrial adoption of ammonia as a hydrogen carrier.
Innovation Solution
A system comprising parallel first reactors for ammonia decomposition and nitrogen adsorption, followed by parallel second reactors for catalyst and adsorbent regeneration, utilizing metal organic frameworks and catalysts like barium-promoted cobalt-cerium for efficient in-situ nitrogen separation and continuous regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional separation steps are used for ammonia decomposition products, then complete separation of hydrogen and nitrogen is achieved, but the process complexity and inefficiency increase
Solution Approach 1:
The patent combines the ammonia decomposition catalyst and nitrogen selective adsorbent into a single integrated fixed bed, merging two separate process units (decomposition and separation) into one. This eliminates complex multi-step separation equipment while achieving both hydrogen production and nitrogen removal simultaneously, directly resolving the contradiction between separation completeness and process complexity
2Productivity
If in-situ nitrogen adsorption is implemented, then reaction rate increases due to reduced product concentration, but the need for continuous regeneration of adsorbent adds operational complexity
Solution Approach 1:
The patent divides the system into multiple parallel reactors that operate in alternating cycles: some reactors perform ammonia decomposition while others undergo adsorbent regeneration. This segmentation allows continuous operation without interruption, maintaining high reaction rates while distributing the regeneration burden across multiple units, thus resolving the contradiction between productivity and ease of operation
Solution Approach 2:
The system employs periodic switching between decomposition mode and regeneration mode across parallel reactors. Each reactor alternates between producing hydrogen via ammonia decomposition and being regenerated to remove accumulated nitrogen. This periodic action ensures continuous high productivity while managing operational complexity through automated cycle switching
3Duration of action of stationary object
If parallel reactors with sequential operation are used, then continuous ammonia decomposition is achieved, but the system requires multiple reactors increasing initial complexity
Solution Approach 1:
Each reactor in the parallel system is designed to perform multiple functions: ammonia decomposition, nitrogen adsorption, and self-regeneration. This multi-functionality reduces the need for separate dedicated units for each process step, thereby achieving continuous operation while minimizing the total number of reactors required, resolving the contradiction between continuous operation capability and device complexity
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
Enhances the efficiency of ammonia decomposition by reducing product concentration through in-situ nitrogen adsorption, increasing reaction rate, and facilitating continuous operation with sequential adsorption and desorption steps.
Implementation Method 1
a N2 selective adsorbent for in-situ adsorbing N2 from the gas mixture to form a N2-containing adsorbent
Implementation Method 2
a catalyst for decomposing NH3 to a gas mixture containing N2 and H2
Implementation Method 3
heating or pressurizing the second fixed adsorbent and catalyst bed to release the N2 from the second N2-containing adsorbent
Data Source
AI summary
A fixed adsorbent and catalyst bed containing system includes two or more first reactors in a reaction (RM) mode and two or more second reactors in a regeneration (RGM) mode that are sequentially operable and positioned in parallel. The two or more first reactors in the RM mode are configured to simultaneously in-situ decompose NH3 by a catalyst and selectively adsorb N2 by an adsorbent. At a substantially same time, the two or more second reactors in the RGM mode are configured to continuously regenerate the catalyst after decomposing the NH3 and the adsorbent after adsorbing the N2. A moving adsorbent bed and fixed catalyst bed containing system and a dual fluidized bed containing system are also provided. The present invention also relates to methods for decomposing ammonia (NH3) to nitrogen (N2) and hydrogen (H2).