CO2 and CH4 permeation through T-type zeolite membranes: Effect of synthesis parameters and feed pressure

A comprehensive review on zeolite-based mixed matrix membranes for CO2/CH4 separation

Biogas consisting of carbon dioxide/methane (CO₂/CH₄) gas mixtures has emerged as an alternative renewable fuel to natural gas. The presence of CO₂ can decrease the calorific value and generate greenhouse gas. Hence, separating CO₂ from CH₄ is a vital step in enhancing the use of biogas. Zeolite and zeolite-based mixed matrix membrane (MMM) is considered an auspicious candidate for CO₂/CH₄ separation due to thermal and chemical stability. This review initially addresses the development of zeolite and zeolite-based MMM for the CO₂/CH₄ separation. The highest performance in terms of CO₂ permeance and CO₂/CH₄ selectivity was achieved using zeolite and zeolite-based MMM, which exhibited CO₂ permeance in the range of 2.0 × 10^{- 7}-7.0 × 10^{- 6} mol m^{- 2} s^{- 1} Pa^{- 1} with CO₂/CH₄ selectivity ranging from 3 to 300. Current trends directed toward improving CO₂/CH₄ selectivity via modification methods including post-treatment, ion-exchanged, amino silane-grafted, and ionic liquid encapsulated of zeolite-based MMM. Those modification methods improved the defect-free and interfacial adhesions between zeolite particulates and polymer matrices and subsequently enhanced the CO₂/CH₄ selectivity. The modifications via ionic liquid and silane methods more influenced the CO₂/CH₄ selectivity with 90 and 660, respectively. This review also focuses on the possible applications of zeolite-based MMM, which include the purification and treatment of water as well as biomedical applications. Lastly, future advances and opportunities for gas separation applications are also briefly discussed. This review aims to share knowledge regarding zeolite-based MMM and inspire new industrial applications.

Optimization of CO2/H2 Separation over Ba-SAPO-34 Zeolite Membrane Synthesized by Microwave Heating

CO₂/H₂ separation using membrane technology is an important research area in order to obtain high purity hydrogen as one source of clean energy. Finding a suitable inorganic membrane is one of the critical issues, which needs to be explored for CO₂/H₂ separation. In the present study, Ba-SAPO-34 zeolite membrane was synthesized and followed by a modification process. CO₂/H₂ separation of the membrane was investigated by varying the independent process variables (CO₂ % in the feed, pressure difference across the membrane and temperature). Modeling and optimization for the responses (CO₂/H₂ separation selectivity and CO₂ permeance) was performed by applying response surface methodology and central composite design, which is available in Design Expert software. The accuracy of the models in predicting the response was tested by comparing with the experimental value of response and the two values were in good agreement. The optimization of the models gave CO₂ permeance of 19.23 × 10^-7 mol/m² s Pa and CO₂/H₂ separation selectivity of 11.6 at 5% CO₂ in the feed, a pressure difference of 100 kPa, and temperature of 30 °C for Ba-SAPO-34 zeolite membrane.

Biomethane generation from biogas upgrading by means of thin-film composite membrane comprising Linde T and fluorinated polyimide: optimization of fabrication parameters

Generation of biogas from organic substances is an attractive evolution of energy generation from fossil-based energy supply to renewable resources. In order to exhibit viability in terms of technical execution while being economically feasible, successful purification strategies for biomethane formation must be applicable to industrial gas streams at realistic pressures and temperatures. Membrane-based upgrading technologies have great potential to promote biogas processes because they involve less energy and low maintenance. However, the development of membranes with good polymer-filler contact and minimum defects remains a great challenge. Hitherto, researchers have been making many attempts at developing an established route to fabricate thin-film composite membranes. In the present work, an innovative coupling between Linde T and fluorinated polyimide was employed for biogas upgrading. A facile technique for membrane fabrication was proposed via optimization of the fabrication parameters. The results indicated that composite membrane fabricated with 2 hours of total dispersion duration demonstrated a homogeneous distribution of Linde T particles in the fluorinated polyimide matrix and improved the separation characteristics by up to 172% in upgrading biomethane quality. Thus, the fabricated membrane is feasible to be employed for large-scale and lucrative production with enhanced performance in biogas purification via the feasible fabrication method employed in this work.

Generation of biogas from organic substances is an attractive evolution of energy generation from fossil-based energy supply to renewable resources.

Zeolite RHO Synthesis Accelerated by Ultrasonic Irradiation Treatment

In recent years, there are increasing interest on applying ultrasonic irradiation for the synthesis of zeolite due to its advantages including remarkable shortened synthesis duration. In this project, the potential of ultrasonic irradiation treatment on the synthesis of zeolite RHO was investigated. Ultrasonic irradiation treatment time was varied from 30 to 120 minutes for the synthesis of zeolite RHO. The zeolite RHO solid samples were characterized with X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and nitrogen adsorption-desorption analysis. The application of ultrasonic irradiation treatment in this study has accelerated the synthesis of zeolite RHO where the synthesis duration has been significantly shortened to 2 days compared to 8 days required by conventional hydrothermal heating without ultrasonic irradiation treatment. Highly crystalline zeolite RHO crystals in truncated octahedron morphology were successfully formed.

Recent advances in preparation methods for catalytic thin films and coatings

Advancements in the preparation methods and applications of catalytic thin films and coatings are briefly summarized.

An enhanced hybrid membrane of ZIF-8 and zeolite T for CO2/CH4 separation

Vacuum thermal seeding was performed to synthesize the ZIF-8 membrane, followed by fabrication of zeolite T on the ZIF-8 layer. The synergistic effect of both materials on the gas separation mechanism has resulted in high CO₂/CH₄ selectivity.