PEBAX-1657/Ag nanoparticles/7,7,8,8-tetracyanoquinodimethane complex for highly permeable composite membranes with long-term stability

Minsu Kim,Sang Wook Kang

doi:10.1038/s41598-019-40185-6

Abstract

Poly (ether-block-amide) resin-1657 (PEBAX-1657)/silver nanoparticle (AgNPs)/7,7,8,8-tetracyanoquinodimethane (TCNQ) composite membranes were prepared for olefin/paraffin separation. The long-term performance of composite membranes can be improved by preventing the reduction of silver ions by adding Al(NO3)3 and PEBAX-1657, which has 40% amide groups and 60% ether groups, to the polymer matrix for high permeance. In this study, silver ions were reduced to form nanoparticles to which 7,7,8,8-tetracyanoquinodimethane (TCNQ, electron acceptor) was added to produce long-term olefin carriers. The surface of the AgNPs were modified using electron TCNQ to induce positive charges. The polarized surface of the AgNPs in the PEBAX-1657 permeable polymer matrix interacted with olefins. The membrane was expected to show exceptional separation performance. The results showed that the PEBAX-1657/AgNPs/TCNQ composite membrane exhibited a selectivity of 12.7 and a mixed-gas permeance of 10.2 GPU for durations longer than 76 h. The surface-activated AgNPs were characterized using infrared spectroscopy and X-ray photoelectron spectroscopy.

Highlights

With an increase in the demand for synthetic resins, fibers, and rubbers, the petrochemical industry that produces the raw materials for these products is becoming increasingly large-scale[1]
When silver salts such as AgBF4 or AgClO4 are dissolved in polar polymers such as polyvinylpyrrolidone (PVP), poly(ethylene oxide) (PEO), or polymethacrylates (PMA), free silver ions are produced through the formation of solid polymer electrolytes[19,20,21,22,23,24]
Silver ion-based solid polymer electrolyte membranes are not as efficient as the distillation separation method for separating olefin/paraffin mixtures. Polar polymers such as poly(2-ethyl-2-oxazoline) (POZ), PEO, and PVP act as the reducing agents for silver ions, which are reduced to nanoparticles

Summary

Introduction

With an increase in the demand for synthetic resins, fibers, and rubbers, the petrochemical industry that produces the raw materials for these products is becoming increasingly large-scale[1]. This method offers improved selectivity and permeance and results in a stable performance because it utilizes silver ions that have already been reduced. The PVP/AgNPs/p-BQ composite membrane exhibited a propylene/propane selectivity of 1 and a total gas permeance of 0.8 GPU (1 GPU = 1 × 10−6 cm[3] (STP)/(cm[2] s cm Hg))[30].

Results

Conclusion