Mass produced NaA zeolite membranes for pervaporative recycling of spent N-Methyl-2-Pyrrolidone in the manufacturing process for lithium-ion battery

Abstract

N-methyl pyrrolidone (NMP) is a colorless and odorless liquid that has been heavily used in the manufacturing process of lithium ion batteries. The development of efficient technology for the on-site recycling of NMP is extremely significant in the lithium ion battery manufacturing plant. The pervaporation dehydration by mass produced NaA zeolite membranes followed by vacuum flash vaporization has proven to be an effective and economic way for recovering spent NMP in this paper. The pilot-scale pervaporation plant containing 225 tubular NaA zeolite membranes with a total membrane area of ca. 7.3 m2 was established for dehydration of actual industrial recovered NMP solution from a lithium battery production line. All technical indicators of the retentate (NMP ≥ 99.9%, H2O ≤ 105 ppm, color 10 Hz, refractive index 1.4694) have fully met the requirements of electronic-grade NMP for lithium-ion battery industry. Owing to the excellent molecular sieving effect of NaA zeolite membrane at extremely low water concentration, the NMP recovery yield was far better than the reported values in literature. These results suggested that the mass produced NaA zeolite membranes showed technical feasibility for the recycling of NMP in the lithium ion battery manufacturing process.