Design and development of membranes for CO2/CH4 separation

Abstract

The objective of this work is to compare different membrane materials and different operation modes for the separation of CO2 from CH4. In this context, the working principles in terms of gas transport properties will be evaluated for three different systems. The discussion concerns: (1) poly(ether-b-amide) (PEBAX®1657)/polyacrylonitrile (PAN) composite hollow fibre membranes, (2) CO2-selective facilitated transport membranes, and (3) mixed matrix membranes based on Polymers of Intrinsic Microporosity (PIMs). The Pebax/PAN hollow fibre membranes were prepared by a new continuous coating method based on cross flow-filtration of a PEBAX solution. This allows simultaneous internal coating of a large number of the porous hollow fibres with a thin selective dense layer of PEBAX®, directly inside the module. The membrane preparation was optimized by modulating different parameters, such as coating time, polymer concentration and viscosity. The second approach discusses the potential use of ionic liquids as a vehicle for facilitated CO2 transport in membrane contactors for CO2/CH4 separation. The increase of the CO2 absorption in the ionic liquid [BMIM][OTf] by the use of the enzyme Carbonic Anhydrase (CA) was evaluated. The third approach analyzes the effect of Metal Organic Frameworks (MOFs) on the performance PIM-1 based mixed matrix membranes, provided by the School of Chemistry, University of Manchester (UK). Single gas permeation measurements were carried out to determine the gas separation performance of the membranes. In conclusion, the different types of membranes for CO2/CH4 separation will be compared, discussing the limitations and the advantages of all membranes and methods.