Autothermal Ammonia Cracking with Nickel Catalyst
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Solution Overview
Problem
Current methods for producing nitrogen and hydrogen from ammonia result in the formation of nitrogen oxides, which require additional steps for removal, and are not CO2-free, with inefficiencies in heat utilization and product gas composition.
Innovation Solution
A process involving non-catalytic partial oxidation of ammonia with an oxygen-containing gas followed by cracking over a nickel catalyst, which reduces nitrogen oxides to harmless nitrogen and water, and utilizes reaction heat for endothermic cracking, potentially in a single autothermal reactor, with optional CO2 removal and product gas adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If non-catalytic partial oxidation of ammonia is performed, then heat is produced for the endothermic cracking reaction, but nitrogen oxides are formed as harmful byproducts
Solution Approach 1:
The patent converts the harmful nitrogen oxides formed during partial oxidation into beneficial products by utilizing the endothermic cracking reaction to reduce them. The nitrogen oxides react with hydrogen produced during cracking to form nitrogen and water, thereby eliminating the harmful byproduct while maintaining the heat balance of the process.
Solution Approach 2:
The patent combines the partial oxidation step and the cracking step into a single integrated process. The heat generated from partial oxidation is directly utilized for the endothermic cracking reaction, and the nitrogen oxides formed in oxidation are simultaneously reduced during cracking, merging two previously separate processes into one efficient autothermal system.
2Manufacturing precision
If additional steps are added to remove nitrogen oxides, then product purity is improved, but process complexity increases
Solution Approach 1:
The patent merges the nitrogen oxide removal function into the existing cracking step. The cracking reactor simultaneously performs ammonia cracking and nitrogen oxide reduction, eliminating the need for separate removal steps and reducing overall process complexity while achieving high product purity.
Solution Approach 2:
The cracking reactor is designed to perform multiple functions: cracking ammonia to produce hydrogen and nitrogen, reducing nitrogen oxides to harmless products, and maintaining heat balance. This multi-functional approach eliminates the need for dedicated removal equipment and simplifies the overall process.
3Productivity
If catalytic cracking is used to crack ammonia, then cracking efficiency is improved, but nitrogen oxides require additional removal steps
Solution Approach 1:
The patent utilizes the cracking reaction conditions to convert the harmful nitrogen oxides into beneficial nitrogen and water products. The same catalytic cracking process that efficiently cracks ammonia also reduces nitrogen oxides, transforming a problem into a solution without requiring additional removal steps.
4Manufacturing precision
If the process is not CO2-free, then additional CO2 removal steps are needed, but this increases equipment complexity and operating costs
Solution Approach 1:
The patent creates a CO2-free environment by carefully controlling the oxidation step to avoid CO2 formation. By using controlled partial oxidation with proper oxygen-to-ammonia ratios and subsequent cracking, the process eliminates CO2 generation at the source, avoiding the need for CO2 removal equipment and maintaining an inert-like atmosphere free of carbon contaminants.
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 process significantly reduces nitrogen oxide generation by over 80%, achieves CO2-free hydrogen production, and optimizes heat utilization, allowing for efficient production of a nitrogen and hydrogen gas mixture with adjustable composition.
Implementation Method 1
cracking of at least a part of the residual amounts of ammonia to hydrogen and nitrogen in the process gas by contact with a nickel containing catalyst
Implementation Method 2
heat produced in exothermic non-catalytic partial oxidation of ammonia by the following reaction 2 NH3 + 3/2 O2 → N2 + 3 H2O is sufficient to provide the necessary heat when subsequently performing the endothermic catalytic cracking
Implementation Method 3
The reaction is endothermic, requiring heat for maintaining the ammonia cracking reaction
Implementation Method 4
The nitrogen oxides are reduced by the hydrogen formed during the ammonia cracking reaction to harmless nitrogen and water
Data Source
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AI summary
Process for the production of a product gas containing nitrogen and hydrogen from ammonia comprising the steps of non-catalytic partial oxidation of ammonia with an oxygen containing gas to a process gas containing nitrogen, water, amounts of nitrogen oxides and residual amounts of ammonia; cracking of at least a part of the residual amounts of ammonia to hydrogen and nitrogen in the process gas by contact with a nickel containing catalyst and simultaneously reducing the amounts of nitrogen oxides to nitrogen and water by reaction with a part of the hydrogen formed during cracking of the process gas by contact of the process gas with the nickel containing catalyst; and withdrawing the hydrogen and nitrogen containing product gas.