Two-Zone Molten Pyrolysis Reactor for Carbon Separation
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Solution Overview
Problem
Existing molten metal pyrolysis methods face challenges in efficiently separating solid carbon from molten metal, leading to catalyst deactivation and reactor blockage, while also producing high CO2 emissions and not effectively utilizing impurities in hydrocarbon feedstocks.
Innovation Solution
A two-zone pyrolysis reactor system using molten metal and molten salt layers to separate solid carbon and other products based on density differences, allowing for the conversion of hydrocarbons into valuable products like hydrogen, ammonia, and sulfur, while minimizing CO2 emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solid carbon accumulates on molten metal surface, then carbon separation is simplified, but catalyst deactivation and reactor blockage occur
Solution Approach 1:
A molten salt layer is introduced as an intermediary substance between the molten metal catalyst and the solid carbon product. This salt layer receives the carbon from the molten metal surface while protecting the catalyst from direct contact with accumulated carbon, thus preventing deactivation and blockage while maintaining separation efficiency.
2Quantity of substance
If conventional spray drying method is used for carbon production, then carbon is produced, but high CO2 emissions (2.5-4 ton CO2 per ton of carbon) occur
Solution Approach 1:
The process changes the fundamental parameter of carbon production from combustion-based (conventional spray drying) to pyrolysis-based. By using thermal decomposition in an oxygen-limited environment, the method produces solid carbon with negligible CO2 emissions, transforming the chemical reaction pathway to eliminate harmful emissions.
3Quantity of substance
If mechanical skimming is used to remove carbon from molten metal, then carbon removal is achieved, but molten metal must be simultaneously removed leading to catalyst depletion
Solution Approach 1:
The molten salt acts as a mediator that selectively accepts carbon from the molten metal surface without requiring removal of the molten metal itself. This allows continuous carbon removal while the catalyst remains in place, preventing depletion and maintaining system integrity.
4Quantity of substance
If gas flow is used to blow carbon away from molten metal, then carbon is removed, but carbon-metal interaction is not addressed
Solution Approach 1:
The molten salt layer serves as a physical barrier and intermediary that prevents direct contact between carbon and molten metal. Unlike gas flow methods that only move carbon without protecting the catalyst, the salt layer fundamentally blocks carbon-metal interaction while still enabling carbon removal.
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 method achieves efficient separation of solid carbon and other products from molten metal, reduces CO2 emissions, and converts impurities in hydrocarbon feedstocks into useful gases and liquids, enhancing the overall process efficiency and economic viability.
Implementation Method 1
catalytic molten metals for the direct conversion of methane to hydrogen and separable carbon
Implementation Method 2
Molten metal pyrolysis has emerged recently as a new method to produce H2 and solid carbon
Implementation Method 3
Both these species have a lower density than the molten metal, causing the products to diffuse towards the top of the liquid metal layer
Implementation Method 4
Liquid salt is used to separate produced carbon from the molten metal and to facilitate isolation of produced carbon
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The present invention relates to a method for molten metal pyrolysis of a feed comprising hydrocarbons and nitrogen and/or hydrogen sulphide to produce solid carbon and one or more of liquid sulfur, hydrogen gas and ammonia gas. The molten salt layer contains two reaction zones of different temperatures, a high temperature zone for pyrolysing the hydrocarbon and a low temperature zone for pyrolysing the hydrogen sulphide and/.or forming the ammonia. Liquid salt is used to separate produced solid carbon and optionally the produced liquid sulphur from the molten metal and to facilitate isolation of produced carbon. The invention further relates to a reactor for performing the method according to the invention.