Multi-Layer Catalytic Pre-Purification for Cryogenic Air Separation
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Solution Overview
Problem
Current pre-purification systems for cryogenic air separation units are costly and inefficient in removing hydrogen, carbon monoxide, water, and carbon dioxide from feed air streams, as they rely on expensive catalytic materials and multiple layers with varying effectiveness.
Innovation Solution
A multi-layer pre-purification system comprising a first catalyst layer of manganese and copper oxides to remove carbon monoxide and hydrogen, followed by an adsorbent layer to remove water and carbon dioxide, and a second catalyst layer to further purify the stream, specifically using a noble metal-based catalyst like palladium on aluminum oxide to achieve high purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional catalytic pre-purification techniques are used to remove hydrogen and carbon monoxide, then purification effectiveness is improved, but system cost increases due to expensive catalytic materials
Solution Approach 1:
The pre-purification system is divided into multiple sequential stages: a first catalytic stage for initial removal of hydrogen and carbon monoxide, followed by a second catalytic stage for further purification. This segmentation allows each stage to be optimized for specific purification requirements, achieving high overall effectiveness while managing material costs through staged implementation
Solution Approach 2:
The system employs composite catalytic materials combining different catalyst types in sequence - using base metal catalysts in the first stage for bulk removal, and precious metal catalysts in the second stage for trace removal. This composite approach maximizes purification effectiveness while minimizing the total amount of expensive materials required
2Manufacturing precision
If multiple layers of adsorbent materials are used to remove water and carbon dioxide, then purification effectiveness is improved, but device complexity increases
Solution Approach 1:
The system combines catalytic removal and adsorptive removal into a unified pre-purification process. The catalytic stages convert hydrogen and carbon monoxide into water and carbon dioxide, which are then simultaneously removed by the downstream adsorbent layers. This merging of mechanisms achieves comprehensive purification while streamlining the overall system architecture
Solution Approach 2:
The catalytic conversion of hydrogen and carbon monoxide is performed as a preliminary action before the adsorbent layers. By converting these gases into water and carbon dioxide upfront, the subsequent adsorption stage only needs to handle these two components, simplifying the adsorbent layer design and reducing the number of required layers
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 system effectively reduces costs while achieving high purity by sequentially removing hydrogen, carbon monoxide, water, and carbon dioxide, maintaining efficiency and performance over prior art methods.
Implementation Method 1
passing the gas stream substantially free of carbon dioxide and water through a first catalyst layer comprising a mixture manganese and copper oxides configured to remove at least some of the carbon monoxide and hydrogen from the gas stream
Implementation Method 2
passing the first intermediate effluent through an adsorbent layer disposed downstream of the first catalyst layer, the adsorbent layer configured to remove water and carbon dioxide from the intermediate effluent
Implementation Method 3
passing the second intermediate effluent through a second catalyst layer disposed downstream of the adsorbent layer, the second catalyst layer configured to remove at least hydrogen from the second intermediate effluent
Data Source
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AI summary
A system and method of pre-purification of a feed gas stream is provided that is particularly suitable for pre-purification of a feed air stream in cryogenic air separation unit. The disclosed pre-purification systems and methods are configured to remove substantially all of the hydrogen, carbon monoxide, water, and carbon dioxide impurities from a feed air stream and is particularly suitable for use in a high purity or ultra-high purity nitrogen plant. The pre-purification systems and methods preferably employ two or more separate layers of hopcalite catalyst with the successive layers of the hopcalite separated by a zeolite adsorbent layer that removes water and carbon dioxide produced in the hopcalite layers. Alternatively, the pre-purification systems and methods employ a hopcalite catalyst layer and a noble metal catalyst layer separated by a zeolite adsorbent layer that removes water and carbon dioxide produced in the hopcalite layer.