Modified Zeolite/Polysulfone Mixed Matrix Membrane for Enhanced CO2/CH4 Separation.

Yit Thai Ong,Chii-Dong Ho,Yin Fong Yeong,Tiffany Yit Siew Ng,Zeinab Abbas Jawad,Lanisha Devi Anbealagan,Siew Chun Low,Thiam Leng Chew

doi:10.3390/membranes11080630

Abstract

In recent years, mixed matrix membranes (MMMs) have received worldwide attention for their potential to offer superior gas permeation and separation performance involving CO2 and CH4. However, fabricating defect-free MMMs still remains as a challenge where the incorporation of fillers into MMMs has usually led to some issues including formation of undesirable interfacial voids, which may jeopardize the gas separation performance of the MMMs. This current work investigated the incorporation of zeolite RHO and silane-modified zeolite RHO (NH2–RHO) into polysulfone (PSf) based MMMs with the primary aim of enhancing the membrane’s gas permeation and separation performance. The synthesized zeolite RHO, NH2–RHO, and fabricated membranes were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared-attenuated total reflection (FTIR-ATR), thermogravimetric analysis (TGA) and field emission scanning election microscopy (FESEM). The effects of zeolite loading in the MMMs on the CO2/CH4 separation performance were investigated. By incorporating 1 wt% of zeolite RHO into the MMMs, the CO2 permeability and ideal CO2/CH4 selectivity slightly increased by 4.2% and 2.7%, respectively, compared to that of a pristine PSf membrane. On the other hand, a significant enhancement of 45% in ideal CO2/CH4 selectivity was attained by MMMs incorporated with 2 wt% of zeolite NH2-RHO compared to a pristine PSf membrane. Besides, all MMMs incorporated with zeolite NH2-RHO displayed higher ideal CO2/CH4 selectivity than that of the MMMs incorporated with zeolite RHO. By incorporating 1–3 wt% zeolite NH2-RHO into PSf matrix, MMMs without interfacial voids were successfully fabricated. Consequently, significant enhancement in ideal CO2/CH4 selectivity was enabled by the incorporation of zeolite NH2–RHO into MMMs.

Highlights

Carbon dioxide (CO2 ) is commonly found in many industrial gas streams, such as natural gas stream and flue gas stream
Portrayed similar sharp diffraction peaks to that of zeolite RHO as displayed in Figure 2b, which indicates a high degree of crystallographic regularity in the synthesized zeolite NH2 -RHO
This situation can be explained by the incorporation of silane modification to the zeolite RHO surface where APTES slightly disrupted the crystalline structure of zeolite NH2 -RHO, causing in a slight decrement of crystallinity [34]

Summary

Introduction

Carbon dioxide (CO2 ) is commonly found in many industrial gas streams, such as natural gas stream and flue gas stream. CO2 /CH4 and CO2 /N2 separations are among the most important gas separation processes This is because the presence of CO2 in the gas stream reduces the calorific value of the gas stream. Membrane technology has received worldwide attention in the application of gas separation over the decades This is due to the fact that membrane technology demonstrates advantages such as low energy consumption, compact design, simplicity of operation, flexibility of scale-up, possible use for continuous operation, and no requirement for phase change [1,2,3]. Polymeric membranes used to be very appealing in industrial gas separations due to its ease in scaling up and low fabrication cost. These membranes commonly suffer an extremity in the tradeoff relation between permeability and selectivity [4]

Methods

Results

Conclusion