Macrocyclic Chelating Agents for Barium Scale Dissolution
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Solution Overview
Problem
The petroleum industry faces challenges in efficiently and safely removing barium sulfate (BaSO4) scales due to their insolubility, which leads to economic burdens and health hazards, as conventional chelating agents like DTPA and DOTA have low affinity and slow kinetics for Ba2+, making selective and rapid chelation elusive.
Innovation Solution
A metal-chelating composition with a specific structure, such as macropa, macropaquin, and macroquin-SO3, is used to selectively chelate barium and radium ions by contacting a salt of the metal ion with the composition in an aqueous-based liquid, facilitating the dissolution of BaSO4 scales under mild conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional chelating agents like DTPA are used to remove BaSO4 scale, then the scale can be dissolved under extreme conditions (high pH and heat), but the process requires extreme conditions and has low efficiency
Solution Approach 1:
The patent changes the chemical parameters by introducing a novel chelating agent with a different molecular structure (containing a 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane core with picolinate or hydroxyquinoline arms) that has higher thermodynamic affinity and faster kinetics for Ba2+ ions. This allows the dissolution process to proceed under milder temperature and pH conditions compared to conventional DTPA, directly resolving the contradiction between removal efficiency and processing severity
Solution Approach 2:
The invention employs a composite chelating agent design that combines a macrocyclic crown ether core (1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) with pendant aromatic carboxylate groups (picolinate or hydroxyquinoline). This composite structure synergistically provides both high thermodynamic stability (through the macrocyclic effect) and fast kinetics (through the pre-organized binding sites), enabling efficient scale removal under mild conditions
2Stability of the object's composition
If DOTA is used to chelate Ba2+, then high thermodynamic affinity is achieved, but the metal-binding kinetics are slow
Solution Approach 1:
The patent introduces dynamic flexibility into the chelating agent design by using aliphatic linkers (ethylene or propylene groups) connecting the macrocyclic core to the aromatic pendant arms. This dynamic structure allows the ligand to adapt its conformation during metal binding, facilitating faster exchange kinetics compared to the rigid DOTA structure, while maintaining high stability through the pre-organized macrocyclic framework
Solution Approach 2:
The chelating agent is segmented into distinct functional modules: a macrocyclic core providing cavity size match for Ba2+, flexible aliphatic linkers enabling conformational adaptation, and aromatic carboxylate arms providing high-affinity binding sites. This segmentation allows each module to optimize its function independently, achieving both fast kinetics (through linker flexibility) and high stability (through core and arm coordination)
3Temperature
If DTPA is used for scale removal, then the process can proceed under milder conditions compared to extreme pH and heat, but the affinity for Ba2+ is low
Solution Approach 1:
The patent modifies the chelating agent parameters by replacing DTPA's acyclic structure with a macrocyclic framework containing 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane. This structural parameter change increases the charge density and pre-organization of binding sites, enhancing Ba2+ affinity while allowing the process to proceed under milder conditions due to the higher intrinsic stability of the complex
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 described metal-chelating composition effectively dissolves BaSO4 scales under mild temperatures and neutral pH, outperforming conventional ligands in terms of affinity and kinetics, enabling efficient scale removal and potential reuse of the ligand, thus addressing the industrial and safety concerns.
Implementation Method 1
A metal-chelating composition with a specific structure, such as macropa, macropaquin, and macroquin-SO3, is used to selectively chelate barium and radium ions
Data Source
AI summary
Metal-chelating compositions having the structure (1a) wherein: R1, R2, R3, and R4 are independently selected from the following groups: (i) hydrogen atom, (ii) hydrocarbon groups (R) containing 1-12 carbon atoms; (iii) halogen atoms; (iv) —P(R5) (═O)OH groups; (v) —C(═O)OH groups; (vi) —S(═O)2OH groups; and (vii) —OH groups, wherein R5 is selected from hydrocarbon groups (R) and —OH; R1 and R2 may optionally interconnect to form Ring A fused to the ring on which R1 and R2 are present; R3 and R4 may optionally interconnect to form Ring B fused to the ring on which R3 and R4 are present; wherein Ring A and Ring B are optionally and independently substituted with one or more of groups (ii)-(vii). Methods of using the above-described compositions for chelating metal ions having an atomic number of at least 56 (e.g., Ba or Ra) are also described.