Amorphous Halogen Sorbent for Mercury Sequestration
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Solution Overview
Problem
Current sorbent compositions for mercury capture in flue gas streams, particularly those using halogen salts, face limitations in reactivity and efficiency due to factors like crystallite size, surface area, volatility, and poisoning by acid gases, which restrict the degree of mercury oxidation and sequestration.
Innovation Solution
A sorbent composition is formed by contacting a solid sorbent with an acidic halogen solution containing a halogen species derived from a halide salt, enhancing mercury oxidation and sequestration through the use of an amorphous halogen form, which is achieved by dissolving the halide salt in an aqueous solvent and combining it with an acid, resulting in improved mercury capture efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halogen salts are added to sorbent composition to enhance mercury capture, then mercury oxidation capability is improved, but reactivity is limited by crystallite size, surface area, and volatility
Solution Approach 1:
The patent changes the physical state of halogen from crystalline solid to amorphous form by dissolving halide salts in aqueous solvent and combining with acid. This parameter change increases surface area and eliminates crystallite size limitations, thereby improving reaction rate while maintaining mercury capture efficiency.
Solution Approach 2:
The patent utilizes phase transition from crystalline to amorphous state of halogen species. By transitioning halogen from ordered crystalline structure to disordered amorphous form through acid treatment, the surface area and reactivity are enhanced, resolving the contradiction between reliability and productivity.
2Reliability
If halogen concentration is increased to improve mercury oxidation, then sequestration capability is enhanced, but operational costs and environmental impact increase
Solution Approach 1:
The patent changes the chemical environment by introducing acid to form amorphous halogen species. This parameter change increases the reactivity and accessibility of halogen atoms, allowing effective mercury sequestration at lower halogen concentrations, thus reducing quantity of substance required.
Solution Approach 2:
The patent creates a composite structure where halogen species are embedded in an amorphous matrix formed by acid treatment. This composite approach enhances the utilization efficiency of halogen, improving sequestration capability while reducing the total amount of halogen needed.
3Stability of the object's composition
If halide salts are used in crystalline form, then sorbent composition is stable, but reactivity towards mercury oxidation is limited
Solution Approach 1:
The patent changes the structural parameter of halogen from crystalline to amorphous form through acid treatment. This transformation maintains the stability of the overall sorbent composition while dramatically improving the reactivity of halogen species towards mercury oxidation.
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 significantly enhances mercury capture efficiency, achieving improved removal of heavy metals from flue gas streams compared to conventional methods, with the sorbent composition demonstrating enhanced performance at lower halogen concentrations, reducing operational costs and environmental impact.
Implementation Method 1
presumably enhances the oxidation of elemental gas phase mercury to a cationic species that is more strongly sequestered in the pores of the sorbent
Implementation Method 2
contacting a solid sorbent with an acidic halogen solution containing a halogen species derived from a halide salt
Data Source
AI summary
Methods for the manufacture of sorbent compositions, sorbent compositions and methods for using the sorbent compositions. The methods include the utilization of an acidic halogen solution as a source of a halogen species that is dispersed on a solid sorbent. The use of the acidic halogen solution results in a highly active halogen species that demonstrates improved efficacy for the removal of heavy metal(s) from a flue gas. The sorbent composition includes a substantially amorphous halogen species associated with a solid sorbent such as powdered activated carbon (PAC).