Post-Crosslinked Adsorbent with Controlled Micropores
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Solution Overview
Problem
Highly cross-linked polymeric adsorbents with high micropore content suffer from slow desorption rates of adsorbed organic compounds, limiting their effectiveness in recovery processes.
Innovation Solution
A one-pot method for producing post-crosslinked aromatic copolymers with reduced micropore content by suspension copolymerizing monomers in the presence of a porogen, followed by post-crosslinking with a free radical initiator and porogen/water co-solvent, without removing the porogen, resulting in adsorbents with high specific surface area and low micropore volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the content of cross-linker is increased to highly cross-linked extent, then the porosity and surface area of the copolymers are increased, but the micropore content exceeds 30% of total pore volume causing slow desorption rate
Solution Approach 1:
The patent applies preliminary action by conducting post-crosslinking reaction in the presence of porogen before the porogen is removed. This sequence prevents the formation of excessive micropores that would otherwise occur if crosslinking were performed after porogen removal. The crosslinking structure is established while porogen molecules are still present to maintain mesopore architecture, thereby achieving high surface area with controlled micropore content and fast desorption rate.
2Quantity of substance
If the copolymer is dried to remove porogen, then the micropore content increases to more than 30% of total pore volume, but this high micropore content causes difficulty in thorough and quick desorption of adsorbed compounds
Solution Approach 1:
The patent performs post-crosslinking before porogen removal, establishing the crosslinked network while porogen maintains the mesopore structure. This preliminary crosslinking action prevents subsequent micropore formation that would occur upon porogen removal from non-crosslinked copolymers, thereby maintaining high porosity with low micropore content and ensuring efficient desorption.
Solution Approach 2:
The patent changes the physical and chemical parameters of the copolymer system by introducing crosslinking during porogen presence. This parameter change transforms the copolymer from a linear structure to a crosslinked network, fundamentally altering the pore structure development during subsequent porogen removal and drying, resulting in controlled micropore content while maintaining high porosity.
3Manufacturing precision
If distilling removal of porogen and drying is performed on initial copolymer, then micropore content increases significantly, but the adsorbent structure becomes less effective for recovery processes
Solution Approach 1:
The patent merges the post-crosslinking step with the porogen retention stage, performing both crosslinking and porogen removal in sequence without isolating the copolymer intermediate. This combination eliminates the need for separate crosslinking and porogen removal operations, simplifying the manufacturing process while achieving precise control over the final pore structure with low micropore content.
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 produces adsorbents with enhanced adsorption and desorption performance, allowing for easier release of adsorbed compounds and improved recovery efficiency.
Implementation Method 1
post-crosslinking the copolymer with the porogen in the presence of free radical initiator
Implementation Method 2
The adsorbent with high porosity and low micropore content enables the adsorbed compounds be easily desorbed from the resin
Implementation Method 3
the adsorbent with high porosity and low micropore content enables the adsorbed compounds be easily desorbed from the resin
Data Source
AI summary
A post-crosslinked adsorbent comprises: monomer units of (a) at least 55 wt % at least one polyvinylaromatic monomer and (b) up to 45 wt % at least one monovinylaromatic monomer; and 0.5-2.5 mmol/g pendent vinyl groups; wherein the dry adsorbent has BET specific surface area in the range of about 650-1000 m2/g, BET average pore diameter 7.2-10 nm, BET porosity 1.29-2.45 mL/g, BJH adsorption micropore volume was less than 20% of total BJH adsorption pore volume, and HK micropore volume was less than 21% of total BJH adsorption pore volume. The invention is also directed to a preparation method for the polymeric adsorbent.