Rizwan Nasir

Latest Development on Membrane Fabrication for Natural Gas Purification: A Review

In the last few decades, membrane technology has been a great attention for gas separation technology especially for natural gas sweetening. The intrinsic character of membranes makes them fit for process escalation, and this versatility could be the significant factor to induce membrane technology in most gas separation areas. Membranes were synthesized with various materials which depended on the applications. The fabrication of polymeric membrane was one of the fastest growing fields of membrane technology. However, polymeric membranes could not meet the separation performances required especially in high operating pressure due to deficiencies problem. The chemistry and structure of support materials like inorganic membranes were also one of the focus areas when inorganic membranes showed some positive results towards gas separation. However, the materials are somewhat lacking to meet the separation performance requirement. Mixed matrix membrane (MMM) which is comprising polymeric and inorganic membranes presents an interesting approach for enhancing the separation performance. Nevertheless, MMM is yet to be commercialized as the material combinations are still in the research stage. This paper highlights the potential promising areas of research in gas separation by taking into account the material selections and the addition of a third component for conventional MMM.

Effect of fixed carbon molecular sieve (CMS) loading and various di-ethanolamine (DEA) concentrations on the performance of a mixed matrix membrane for CO2/CH4 separation

Polyethersulfone (PES) as a polymer along with carbon molecular sieves (CMS) as an inorganic filler and di-ethanolamine (DEA) as the third component were used to fabricate amine mixed matrix membranes (A3Ms). The CMS and the developed membranes were characterized by variable pressure field emission scanning electron microscopy (VPFESEM) and thermal gravimetric analysis (TGA). FESEM micrographs showed that with the addition of DEA, uniform distribution of CMS particles in the PES matrix was achieved with good polymer-filler contact. The combined effect of DEA concentration (5–15 wt%), feed pressure (2–10 bar) and CMS loading on the CO2/CH4 transport properties of the PES–CMS–DEA membranes were studied. The results revealed that the PES–CMS–DEA (15 wt% DEA) membrane showed a CO2 permeance of 123.49 GPU at 2 bar, which is more than a threefold increment with respect to the native PES membrane. The corresponding CO2/CH4 ideal selectivity was increased from 5.40 for PES to 51.39 for PES–CMS–DEA (15 wt% DEA). The CO2 permeance of the PES–CMS–DEA (A3Ms) membranes was higher than PES membranes over the operating pressure range.

Surface modification in inorganic filler of mixed matrix membrane for enhancing the gas separation performance

Abstract The development of mixed matrix membrane (MMM) in gas separation process has drawn great attention due to its promising properties. MMM consists of a polymer as the matrix phase, whereas the inorganic filler serves as the dispersed phase. However, poor contact between these two phases often results in unselective gas flow and becomes one of the major issues in the MMM development. Currently, various modification techniques of the inorganic filler to improve the compatibility between the polymers and the particles have been reported. Because of this modification, the CO2 separation from natural gas is expected to enhance. This review provides a better understanding about the modification of inorganic filler. Mechanisms and factors affecting the modification of filler such as the effect of solvent polarity, the effect of water content in solvent, and the effect of drying condition are discussed. The details of the current progress in the MMM involving the silane-modified fillers are also summarized.

Prediction of gas transport across amine mixed matrix membranes with ideal morphologies based on the Maxwell model

The incorporation of highly selective molecular sieve such as carbon molecular sieve (CMS) and highly affinitive solvent such as diethanolamine (DEA) into polyethersulfone (PES) have been implemented to synthesize amine mixed matrix membranes (MMMs) with an enhanced gas performance. Synergetic effect of CMS and DEA has caused the improvement of carbon dioxide (CO2) permeability and ideal CO2/CH4 selectivity. While existing theoretical models define the relative permeability well for binary mixed matrix membranes they fail to predict the relative permeability of amine mixed matrix membranes. In fact, the degree of deviation from the simple model predictions provides understanding into the detailed properties of the third component, which has been neglected in previous analyses of these models. Modification of an existing model, namely the Maxwell model, provides an outline to analyze the gas permeation properties of model systems with CMS and DEA in glassy polymer phase. The new model is developed by modifying the basic Maxwell MMMs model. The modification also includes the optimization of λdm, which is defined as the ratio of dispersed phase permeability to matrix permeability, and the determination of permeability of the dispersed phase. Furthermore, this Maxwell model has been extended to model the performance of amine mixed matrix membranes by incorporation of combined volume fraction of filler and amine φ*ad. The proposed approach can predict the permeability of CO2 through amine MMMs and also lowers the AARE % value.

Fabrication and Characterization of Facilitated Transport Membrane for Gas Separation

The new membrane material containing facilitate transport medium to enhance the performance of gas separation membrane has been fabricated by using monoethanolamine (MEA) as a fixed carrier with different concentration (5 & 10 wt. %) by using the solvent evaporation method. The developed membranes were characterized by using Field Emission Electron Microscope (FESEM), Fourier Transform Infrared (FTIR), and Thermo-Gravimetric Analysis (TGA). The developed membranes were found nonporous and dense in structure.

Effect of Carbon Molecular Sieve (CMS) Concentration on Mixed Matrix Membranes (MMMs) Performance for Carbon Dioxide Removal

Different compositions of carbon molecular sieve (CMS) were incorporated in polyethersulfone (PES) matrix to fabricate mixed matrix membranes (MMMs) by solution casting method. The characterization was carried out using field emission scanning electron microscopy (FESEM) analysis to investigate the morphology of membrane. FESEM images showed acceptable contacts between the filler particles and the polymer chains. The performance of the developed membrane is analyzed by single gas permeation measurement of high purity CO2 and CH4. Both CO2 permeance and CO2/CH4 selectivity increased with CMS loadings as compared to pure PES membrane. Experimental results showed that the highest value of CO2 permeance (66.71 GPU) and CO2/CH4 selectivity (10.94) can be achieved with 30 wt. % loading of CMS particles. This can be credited to size discrimination of CMS pores that falls between CO2 and CH4 kinetic diameters.