Process for preparing coarse-grained anion exchange gel

Abstract

Preparation of monodisperse gel form anion exchangers by: (a) formation of a suspension of seed in a continuous aqueous phase; (b) swelling in a vinyl monomer mixture; (c) polymerization of this in (a); (d) reswelling of monomer mixture; (e) polymerization of second monomer mixture in the first seed / feed polymerisate; and (f) functionalization of the copolymer obtained by chloromethylation and amination. A method for preparation of monodisperse gel form anion exchangers (I) of high stability and purity comprises: (a) forming in a continuous aqueous phase a suspension of seed poplymerisate with a swelling index of 2.5-7.5, and a content of non-evaporatable extractable portion of less than 1 wt.%; (b) swelling the suspended seed polymerisate in a monomer mixture of vinyl monomer, crosslinker, and radical starter; (c) polymerising the monomer mixture in the seed polymerisate; (d) swelling the polymerisate obtained again in the monomer mixture of vinyl monomer, crosslinker, and radical starter; (e) polymerising a second monomer mixture in the first seed / feed polymerisate; and (f) functionalizing the copolymer obtained, of swelling index 1.5-2 and mean diameter greater than 520 micron, by chloromethylation and amination. The particle size is greater than 800 micron. Independent claims are included for: (1) A process for preparation of the crosslinked seed polymerisate from (wt.%):(i) monomer (96.5-99.0), (ii) crosslinker (0.8-2.5), and (iii) aliphatic peroxyester as polymerization initiator; (2) (I) prepared by the method.

Description

technical field [0001] The invention relates to a method for preparing a coarse particle monodisperse anion exchange gel with high stability and purity. Background technique [0002] Recently, since ion exchange beds of coarse particle size are economically advantageous in many applications, the importance of anion exchanger particle sizes as large and uniform as possible has increased, preferably particle sizes > 800 μm. These advantages arise especially from monodisperse ion exchangers. They can be obtained by functionalizing monodisperse bead polymers. [0003] In particular, coarse-grained materials are suitable for gas adsorption, catalysis, and hydrometallurgy. [0004] Ion exchangers with particle sizes ranging from 300 to 800 [mu]m can be prepared by methods commonly used hitherto. This document discloses various processes for the preparation of ion exchangers having a particle size >800 μm, ie can be relatively referred to as crude exchangers. [0005] US ...

AI Technical Summary

Problems solved by technology

[0014] 1. Due to the addition of monomer, part of the polymer is precipitated from the seed, making the particles adhere to each other, which may interrupt the polymerization of the swollen seed;

[0015] 2. In the reaction solution used for functionalization, the concentration of the dissolved part increases, which may make it more difficult to prepare anion exchangers by functionalization;

[0016] 3. The anion exchanger may contain increased amounts of soluble polymers, which may lead to undesired extraction of the ion exchanger

Debris can enter the solution being treated and contaminate the solution in the application, or make the regenerative separation process more difficult and may result in loss of adsorbent material

Also, damaged anion exchangers are not conducive to functionalization of ion exchangers for column processes

Fragmented material causes increased pressure loss in the column system, thus reducing the throughput of purified liquid through the column, or making separation more difficult during batch processes