Halogen-Modified Carbon Sorbent for Mercury Capture
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Solution Overview
Problem
Existing mercury removal technologies from flue gas are inefficient, requiring large amounts of expensive sorbents, generating solid waste, and struggling to effectively capture elemental mercury due to slow capture kinetics and reactivity issues, especially when using activated carbon injection systems.
Innovation Solution
A halogen/halide-promoted sorbent system using activated carbon and non-carbon compounds, such as porous felsic or basaltic materials, with optional secondary components like halogens or hydrohalides, that enhances mercury capture by forming reactive Lewis acid or basic sites for rapid oxidation and adsorption of mercury, allowing for regeneration and reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large amounts of sorbent are used to capture mercury, then mercury removal efficiency is improved, but cost and solid waste generation increase
Solution Approach 1:
The patent modifies the chemical parameters of the sorbent by impregnating it with halogen compounds (chlorine, bromine, or iodine) to transform ordinary activated carbon into a highly reactive sorbent. This parameter change enables the sorbent to effectively capture elemental mercury at much lower dosages, resolving the contradiction between removal efficiency and sorbent quantity required.
Solution Approach 2:
The invention creates a composite material by combining activated carbon with halogen compounds to form a enhanced sorbent. This composite structure leverages the high surface area of activated carbon and the strong oxidizing capability of halogens, achieving superior mercury capture performance with reduced sorbent consumption.
2Reliability
If activated carbon injection is used to remove mercury, then some mercury capture is achieved, but capture kinetics are slow and effectiveness is limited
Solution Approach 1:
The patent employs halogen compounds (particularly bromine and chlorine) as strong oxidants that rapidly oxidize elemental mercury to mercuric halides. This accelerated oxidation process dramatically improves capture kinetics compared to conventional activated carbon alone, directly addressing the slow reaction rate problem.
3Reliability
If metal oxide sorbents are used for mercury capture, then sorbent reactivity is improved, but capture kinetics remain slower than carbon particles
Solution Approach 1:
The invention creates a hybrid composite material combining the advantages of activated carbon (high surface area, fast mass transfer) with halogen compounds (strong oxidizing power). This composite achieves both high reactivity and fast capture kinetics, outperforming metal oxide sorbents while maintaining the speed advantage of carbon-based materials.
4Reliability
If fine sorbent particles are injected into flue gas, then mercury capture capacity is increased, but separation from ash becomes difficult
Solution Approach 1:
The patent uses a halogen-promoted sorbent that achieves high mercury capture capacity per unit mass, allowing the use of optimal particle sizes that balance capture effectiveness with separability. The enhanced reactivity means less sorbent is needed, and the particles can be coarser and easier to separate while maintaining high capture capacity.
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 halogen/halide-promoted sorbent system achieves high mercury removal efficiencies with reduced sorbent requirements, lower costs, and the ability to regenerate and reuse the sorbent, effectively addressing the inefficiencies of existing technologies.
Implementation Method 1
the Lewis basic sites on the promoted sorbent react with elemental or oxidized mercury, or the Lewis acid sites on the promoted sorbent react with oxidized mercury
Implementation Method 2
allowing for rapid oxidation and adsorption of mercury
Data Source
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AI summary
A promoted carbon and/or non-carbon base sorbent are described that are highly effective for the removal of mercury from flue gas streams. The promoted sorbent comprises a carbon and/or non-carbon base sorbent that has reacted with and contains forms of halogen and halides. Optional components may be added to increase and/or preserve reactivity and mercury capacity. These may be added directly with the base sorbent, or in-flight within a gas stream (air, flue gas, etc.), to enhance base sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The promoted sorbent can be regenerated and reused. Base sorbent treatment and preparation methods are also described. New methods for in¬ flight preparation, introduction, and control of the active base sorbent into the mercury contaminated gas stream are described.