Performance Analysis of Blended Membranes of Cellulose Acetate with Variable Degree of Acetylation for CO2/CH4 Separation.

Ayesha Raza,Mohd Hafiz Dzarfan Othman,Muhammad Ahsan,Imranullah Khan,Arshad Hussain,Sarah Farrukh

doi:10.3390/membranes11040245

Ayesha Raza, Mohd Hafiz Dzarfan Othman + Show 4 more

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https://doi.org/10.3390/membranes11040245

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Abstract

The separation and capture of CO2 have become an urgent and important agenda because of the CO2-induced global warming and the requirement of industrial products. Membrane-based technologies have proven to be a promising alternative for CO2 separations. To make the gas-separation membrane process more competitive, productive membrane with high gas permeability and high selectivity is crucial. Herein, we developed new cellulose triacetate (CTA) and cellulose diacetate (CDA) blended membranes for CO2 separations. The CTA and CDA blends were chosen because they have similar chemical structures, good separation performance, and its economical and green nature. The best position in Robeson’s upper bound curve at 5 bar was obtained with the membrane containing 80 wt.% CTA and 20 wt.% CDA, which shows the CO2 permeability of 17.32 barrer and CO2/CH4 selectivity of 18.55. The membrane exhibits 98% enhancement in CO2/CH4 selectivity compared to neat membrane with only a slight reduction in CO2 permeability. The optimal membrane displays a plasticization pressure of 10.48 bar. The newly developed blended membranes show great potential for CO2 separations in the natural gas industry.

Highlights

Natural gas has progressively replaced fossil fuels as the green energy source for modern power plants [1,2]
No additional peak was observed in the cellulose triacetate (CTA)/cellulose diacetate (CDA) blended membrane compared to the pristine membranes, which justifies the physical interaction between the chains of CDA and CTA
FTIR results verified the presence of physical interaction between CTA and CDA polymeric chains

Summary

Introduction

Natural gas has progressively replaced fossil fuels as the green energy source for modern power plants [1,2]. Well ahead in 1970s, CA membranes were adapted for gas separation, mainly for CO2 removal from natural gas and hydrogen purification [8]. Few years later in the mid-1980s, the first commercial CA membrane process was developed for CO2 removal from natural gas, and since it is dominating the market of CO2 membrane separation [9]. The success of CAs is linked to its easy availability, low cost, and stability (both mechanical and chemical). It is the most widely used commercial polymer for CO2 separation. In 2012, CA accounted for up to 80% of the total membrane technology market for natural gas processing [10]. Two leading companies, i.e., UOP Separex and Cynara, are providing CA membranes for natural gas separation [11]

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