A New Industrial Technology for Mass Production of Graphene/PEBA Membranes for CO2/CH4 Selectivity with High Dispersion, Thermal and Mechanical Performance.

Samy Yousef,Paulius Pavelas Danilovas,Nerijus Striūgas,Dainius Martuzevicius,Zahid Sarwar,Edvinas Krugly,Justas Šereika

doi:10.3390/polym12040831

Abstract

Polyether block amide (PEBA) nanocomposite membranes, including Graphene (GA)/PEBA membranes are considered to be a promising emerging technology for removing CO2 from natural gas and biogas. However, poor dispersion of GA in the produced membranes at industrial scale still forms the main barrier to commercialize. Within this frame, this research aims to develop a new industrial approach to produce GA/PEBA granules that could be used as a feedstock material for mass production of GA/PEBA membranes. The developed approach consists of three sequential phases. The first stage was concentrated on production of GA/PEBA granules using extrusion process (at 170–210 °C, depending on GA concentration) in the presence of Paraffin Liquid (PL) as an adhesive layer (between GA and PEBA) and assisted melting of PEBA. The second phase was devoted to production of GA/PEBA membranes using a solution casting method. The last phase was focused on evaluation of CO2/CH4 selectivity of the fabricated membranes at low and high temperatures (25 and 55 °C) at a constant feeding pressure (2 bar) using a test rig built especially for that purpose. The granules and membranes were prepared with different concentrations of GA in the range 0.05 to 0.5 wt.% and constant amount of PL (2 wt.%). Also, the morphology, physical, chemical, thermal, and mechanical behaviors of the synthesized membranes were analyzed with the help of SEM, TEM, XRD, FTIR, TGA-DTG, and universal testing machine. The results showed that incorporation of GA with PEBA using the developed approach resulted in significant improvements in dispersion, thermal, and mechanical properties (higher elasticity increased by ~10%). Also, ideal CO2/CH4 selectivity was improved by 29% at 25 °C and 32% at 55 °C.

Highlights

Natural gas is the cleanest and cheapest fossil fuel available at present
As demand for natural gas has been growing enormously recently, many energy-conversion technologies (e.g., Pyrolysis, fermentation, etc.) were employed to generate biogas from different types of waste in order to compensate the shortage in production of natural gas, and to dispose such waste simultaneously [3,4,5]
At 0.4 wt.% of Graphene nanosheets (GA) (Figure 5G), GA started to distribute uniformly and the surfaces became absolutely rough due to GA incorporated on the surface of the membranes, what leads to increased viscosity of the solution leading to increased surface tension and fast solidification [44,45]

Summary

Introduction

Natural gas is the cleanest and cheapest fossil fuel available at present. Its advantages made it a key player in the field of electricity generation and in majority of critical industrial sectors, including cements, iron and steel, etc. Biogas obtained using such technologies contains many components, 60–70 wt.% of Methane (CH4 ) as a main component, 30–40 wt.% of Carbon dioxide (CO2 ) as a significant impurity in natural gas paths, and some trace elements (e.g., Nitrogen, ammonia, hydrogen sulphide, water vapor, etc.) [6,7]. Presence of CO2 in obtained biogas can result in some serious technical problems, for example, reduced transportation capacity, lower natural-gas heating value, and corrosion of pipeline [8].

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Conclusion