US 12,454,508 B2
Process for the recovery of epsilon-caprolactam from polyamide 6 comprising fishing nets
Jasper Verduyckt, Urmond (NL); Peter Roos, Urmond (NL); Kate Emily Murphy, Urmond (NL); Henricus Anna Christiaan Baur, Urmond (NL); Wenjing Fu, Urmond (NL); and Johan Thomas Tinge, Urmond (NL)
Assigned to CAP III B.V., Urmond (NL)
Appl. No. 18/832,305
Filed by CAP III B.V., Urmond (NL)
PCT Filed Jan. 27, 2023, PCT No. PCT/EP2023/052069
§ 371(c)(1), (2) Date Jul. 23, 2024,
PCT Pub. No. WO2023/144338, PCT Pub. Date Aug. 3, 2023.
Claims priority of application No. 22154098 (EP), filed on Jan. 28, 2022; and application No. 22208659 (EP), filed on Nov. 21, 2022.
Prior Publication US 2025/0136547 A1, May 1, 2025
Int. Cl. C07D 201/12 (2006.01); B09B 3/40 (2022.01); B09B 3/70 (2022.01); B09B 3/80 (2022.01); C07D 201/16 (2006.01); C07D 223/10 (2006.01); B09B 101/75 (2022.01)
CPC C07D 201/16 (2013.01) [B09B 3/40 (2022.01); B09B 3/70 (2022.01); B09B 3/80 (2022.01); B09B 2101/75 (2022.01)] 14 Claims
 
1. A process for recovering purified epsilon-caprolactam from material derived from polyamide 6 comprising fishing nets in a plant, wherein the plant comprises
a depolymerization section [B],
a recovery section [C], and
a purification section [D],
and wherein the process comprises the steps of:
a) charging material derived from polyamide 6 comprising fishing nets to the depolymerization section [B];
b) depolymerizing the material derived from polyamide 6 comprising fishing nets in the depolymerization section [B] at a temperature ranging from 180° C. to 400° C. so that an epsilon-caprolactam comprising stream is obtained;
c) discharging the epsilon-caprolactam comprising stream from the depolymerization section [B] and recovering crude epsilon-caprolactam from said stream in the recovery section [C]; and
d) purifying said crude epsilon-caprolactam in the purification section [D] to obtain purified epsilon-caprolactam wherein the purification comprises the steps of
(i) extracting the crude epsilon-caprolactam with an organic solvent, whereby an organic phase is obtained, and wherein the organic phase comprises the organic solvent, epsilon-caprolactam and impurities;
(ii) switching the solvent by replacing the organic solvent at least partially with water, whereby an aqueous phase comprising water, epsilon-caprolactam and impurities with lower- or higher-boiling points than epsilon-caprolactam is obtained and wherein the solvent switch step (ii) is selected from a process based on back-extraction with water, and a process based on solvent swap distillation, in which the organic solvent is distilled off and water is charged; and
(iii) obtaining purified epsilon-caprolactam by distillative removal of impurities with lower- or higher-boiling points than epsilon-caprolactam from said aqueous phase; and at least one additional step comprising:
after step d)(i), the organic phase obtained in step d)(i) is washed with water or with an aqueous alkaline solution, and
wherein prior to the distillative removal in step d)(iii), an alkali metal hydroxide, is added to the aqueous phase.