Tubular Carbon Membrane Research Articles

P84 Co-Polyimide Based-Tubular Carbon Membrane: Effect of Heating Rates on Helium Separations

Helium is one of the most valuable gases with unique features and properties as well as widely used in various applications. Generally, most of the helium sources was extracted from natural gas and it is very crucial to develop efficient technology for helium recovery from natural gas sources, in order to overcome the deficit of the helium supply. Up to now, there are various available traditional separation methods for helium recovery, however these methods possessed several disadvantages such as expensive in cost and energy intensive. Recently, gas separation by using membranes have been utilized and showed potential in recovering and purifying helium from natural gas. This method directly separating the helium from the methane through natural gas liquefaction process where in this process the helium is recovered from the nitrogen rejection unit (NRU) exit gas. Due to the potential benefits that can be obtained from this membrane-based separation method, this current study is aiming to provide more comprehensive scientific reports on the effects of preparation parameters on the performance of tubular carbon membranes (TCMs) for helium separation. In this study, the carbonization heating rate was varied from 1 to 7°C/min by controlling the final temperature at 800°C under Argon environment for all polymeric tubular membranes. The permeation performance of the resultant TCMs have been determined by using a single permeation apparatus. It is necessary to fine-tuning the carbonization conditions in order to obtain the desired permeation properties. From the results, it can be concluded that the most optimum heating rate was found to be at 3°C/min with 463.86±3.12 selectivity of He/N2separation.

Influence of intermediate layers in tubular carbon membrane for gas separation performance

The main objective of this study is to determine the best intermediate layer for tubular carbon membranes for H2 and He separation. Intermediate layer was applied to strengthen interfacial adhesion between selective carbon layers and tubular support. Three different intermediate layers (alumina powder, carbon molecular sieve (CMS), and carbon pencil) had been evaluated to compare their influence towards the performance of gas separation of the carbon membrane. Tubular carbon membrane was fabricated from PI/NCC-based polymer blends which had been carbonized under Argon atmosphere at 800 °C with a heating rate of 3 °C/min. Based on the scanning electron microscopic (SEM) observations, carbon membrane with alumina powder as an intermediate layer had formed a smoother surface compared to other types of intermediate layers. A high performance of tubular carbon membrane was obtained by employing alumina powder as an intermediate layer, which exhibited the best selectivity of H2/N2 and He/N2 of 447.31 ± 1.45 and 471.72 ± 2.19, respectively.

Impact of stabilization environment and heating rates on P84 co-polyimide/nanocrystaline cellulose carbon membrane for hydrogen enrichment

These past few decades, the separation of various gas mixtures problems in order to obtain high purity gases can be overcome by the introduction of membrane-based technology. This current research was focusing on the development of tubular carbon membranes (TCMs) from polymeric precursors for the separation of hydrogen and nitrogen. The fabrication of TCMs involved the dip coating technique and was using P84 co-polyimide as the main precursor by blending of nanocrystaline cellulose (NCC) as an additive. It was believed a slight adjustment on time, temperature, or environment of the carbonization protocol for the commercially available PI/NCC membranes can alter the final properties of the carbons produced. The modifications on the carbonization parameters such as stabilization conditions and heating rates during fabrication of PI/NCC-based carbon membranes could also affect their gas separation performance. A large variety of TCMs for gas separation have been developed by simple carbonization of a PI/NCC deposited on a ceramic tubular support. Herein, in this study, the effect of different heating rates (1, 3, 5, and 7 °C/min) and stabilization environment (Argon, Nitrogen, and Helium) were investigated for all resultant TCMs. As a result, it was observed that stabilization under Argon environment with heating rate of 3 °C/min produced carbon membranes with the best H2/N2 separation and the highest selectivity of 434.68 ± 1.39, respectively.

P84 Co-polyimide/Nanocrystalline Cellulose (NCC)-based Tubular Carbon Membrane: Effect of Drying Times for Carbon Dioxide Separation at Elevated Carbonization Temperature

In this study, the effect of drying time on the performance of tubular carbon membrane was investigated. P84 co-polyimide blends with Nanocrystalline cellulose (NCC)-based carbon membrane supported on ceramic tube was fabricated through the dip-coating technique. This study aims to investigate the effect of various drying times (12 hours, 24 hours, 3 days and 7 days) on the carbon dioxide separation properties. The gas permeation test of the resultant tubular carbon membrane was determined by using pure gas of CO2 and N2. In order to enhance the membrane performance, final carbonization temperature was executed at 800oC in Argon environment with flow rate of 200 mL/min. From the results, it was found that the best drying times was within 24 hours and such membrane showed the highest CO2/N2 selectivity (66.32±2.18).

Effect of stabilization temperature during pyrolysis process of P84 co-polyimide-based tubular carbon membrane for H2/N2 and He/N2 separations

In this study, the effect of stabilization temperature on the performance of tubular carbon membrane was being investigated. P84 co-polyimide-based tubular carbon membrane will be fabricated through the dip-coating technique. The tubular carbon membrane performance can be controlled by manipulating the pyrolysis conditions which was conducted at different stabilization temperatures of 250, 300, 350, 400, and 450°C under N2 environment (200 ml/min). The prepared membranes were characterized by using scanning electron microscopy (SEM), x-ray diffraction (XRD), and pure gas permeation system. The pure gas of H2, He, and N2 were used to determine the permeation properties of the carbon membrane. The P84 co-polyimide-based tubular carbon membrane stabilized at 300°C demonstrated an excellent permeation property with H2, He, and N2 gas permeance of 1134.51±2.87, 1287.22±2.86 and 2.98±1.28GPU, respectively. The highest H2/N2 and He/N2 selectivity of 380.71±2.34 and 431.95±2.61 was obtained when the stabilization temperature of 450°C was applied. It is concluded that the stabilization temperatures have protrusive effect on the carbon membrane properties specifically their pore structure, and eventually their gas separation properties.

Controlled Dip-coating Times for Improving CO2 Selective of PI/NCCbased Supported Carbon Membrane

Carbon membrane can be regarded as the future separation media in gas separation process due to its high gas separation performance, easy processability, and moderate energy requirement compared to conventional separation process. In this study, the fabrication of tubular carbon membrane prepared from PI blends with nanocrystalline cellulose (NCC) was investigated. The influence of dip-coating duration (15, 30, 45, and 60 min) towards the physicochemical properties and CO2/CH4 and O2/N2 separation was explored. The process of carbonization was conducted at 800°C with rate of heating at 3°C/min under argon gas flow (200 mL/min). Pure gas permeation tests were performed to investigate the prepared carbon membrane’s mechanism of transport at ambient temperature and a feed pressure of 8 bar. The carbon membrane with CO2/CH4 and O2/N2 selectivity of 68.23 ± 3.27 and 9.29 ± 2.54 and CO2 and O2 permeance of 213.56 ± 2.17 and 29.92 ± 1.44 GPU, respectively, were obtained when applying 45 min dip-coating.

Incorporation of thermally labile additives in carbon membrane development for superior gas permeation performance

Incorporating thermally labile polymer additives into carbon membrane development is highly practical due to its process simplicity and effective approach. In this study, different polymer composition of thermally labile additives such as polyvinylpyrrolidone (PVP), microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC) were introduced into the BTDA-TDI/MDI (P84-copolyimide) polymer solution. The P84-copolyimide based carbon tubular membranes were fabricated using dip-coating method and characterized in terms of its thermal stability, structural morphology and gas permeation properties. Initially, the NCC was introduced as a pore performing agent in the carbon membrane fabrication for carbon dioxide (CO2) separation. Our finding indicated that the use of NCC as pore performing agent significantly promoted an increment of pore structure channel in carbon membrane. As a result, the high permeance as well as high selectivity was demonstrated in this study. Pure gas permeation tests were performed using CO2, CH4, O2 and N2 at room temperature. The increment of both gas permeance and selectivity were observed in the NCC-containing carbon membranes prepared with a composition of 7 wt%. The promising CO2/CH4 selectivity of 68.23 ± 3.27, CO2/N2 selectivity of 66.32 ± 2.18 and O2/N2 selectivity of 9.29 ± 2.54 with respect to neat carbon membrane were presented. Thus, upon further investigation, the potential of NCC as thermally labile additive in carbon membrane was assured.

Influence of carbonisation temperature on gas permeation properties of matrimid-based carbon membrane

The utilisation of tubular support for carbon membrane preparation is beneficial for gas separation by providing high membrane area per unit volume and mechanically stronger than conventional flat substrate. In this study, tubular carbon membrane derived from Matrimid was fabricated via dip-coating method and three different carbonisation temperatures were used in order to produce high performance carbon membrane (600 °C, 750 °C and 850 °C). The physicochemical property of the carbon membrane is highly dependent on the final carbonisation temperature. By increasing carbonisation temperature, it will result in higher micropores and increasing gas pair selectivity. Whereas, low carbonisation temperature constricts pore formation and resulting in lower gas separation properties. The carbon membrane carbonised at 850 °C showed the highest gas separation properties of CO2/CH4 selectivity of 87.30 with CO2 permeance of 287.36 GPU. The resulted membrane is compared with literatures and has highlighted the potential of carbon tubular membrane for future membrane development.

Carbon tubular membranes from nanocrystalline cellulose blended with P84 co-polyimide for H2 and He separation

In this study, carbon tubular membranes were produced by employing P84 co-polyimide as a precursor material and nanocrystalline cellulose (NCC) as an additive. The synthesized NCC which was derived from recycled newspaper was used as a pore forming agent for the membrane. Various carbonization temperatures (600, 700, 800, and 900 °C) were used while the stabilization temperature was kept at 300 °C. The measurements of pure gases' (He, H2, and N2) permeance through all carbon tubular membranes produced were carried out at feed pressure of 8 bars. The results showed that higher carbonization temperatures resulted in more selective but less productive carbon membranes. The outcome of this study suggested that carbon tubular membrane fabricated from NCC blending with P84 co-polyimide as a promising candidate for H2 and He recovery application with H2/N2 and He/N2 selectivity of 434.68 ± 1.39 and 463.86 ± 8.12, respectively.

A flow-through tubular catalytic membrane reactor using zirconium sulfate tetrahydrate-impregnated carbon membranes for acidified oil esterification

The water-resistant zirconium sulfate tetrahydrate [Zr(SO4)2·4H2O]/tubular carbon membranes (ZS/TCM) were prepared by the wet impregnation of TCM with different ZS loadings, and used as the heterogeneous solid acid catalyst for the esterification of acidified oil with methanol. The composition and structure of the catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS). Because of the high specific area of TCM, the catalytic activity of 11.4% ZS/TCM was improved by 1.8 times compared with bulk ZS. ZS was highly dispersed on the 11.4% ZS/TCM without ZS phase. Affected by diffusion, the content of the ZS on the membrane surface was higher than that of inside. The catalytic performance of ZS/TCM was further confirmed by the tubular catalytic membrane reactor (TCMR). Most of the fuel properties of acidified oil biodiesel were in accordance with ASTM and GB standards.

Preparation of an asymmetric microporous carbon membrane for ultrafiltration separation: application to the treatment of industrial dyeing effluent

An asymmetric tubular carbon membrane with an ultrafiltration microporous top layer has been prepared using thermosetting phenolic resin and carbon black (CB) as carbon precursors. The membrane was composed of a mesoporous interlayer with an average pore size of 0.6μm deposited by slip casting process on the inner face of a macroporous support. The microporous top layer was deposited by the same process using suspensions of commercial CB powder (44nm average pores size). An initial ultrafiltration membrane with an average pore size of 7.9nm and a thickness of 8.34μm was formed requiring 10 min casting time and a curing–carbonization cycle at 700°C under nitrogen atmosphere. An approach consisting of repeating casting–carbonization cycle was adopted to correct the defects that appeared at the surface. Results showed that an UF-corrected membrane denominated UF-C4 was successfully prepared by adding only one layer after its composition and conditions of deposition were determined. A crack-free UF membrane with a thickness layer of 12.6 μm, a mean pores size of 5.3 nm, and a molecular weight cut-off of 90 kDa was then obtained using only 6 min casting time. It was found that this membrane could be applied efficiently to the treatment of industrial dyeing effluent.

The effect of polymer composition on CO2/CH4 separation of supported carbon membrane

Recently, membrane technology has attracted vast attention from many scientists and engineers, particularly from the industrial area. The membrane for gas separation is favoured due to its economically feasibility and high separation performance with respect to gas permeability and selectivity. In this study, the effect of different polymer concentrations (5, 10, 13, 15 and 18 wt%) on the gas permeation properties of CO2/CH4 separation was investigated. Matrimid 5218 was chosen as the based polymer for tubular carbon membrane preparation owing to its excellent membrane properties (i.e. high mechanical and thermal stability) in order to fulfil the membrane requirement for high gas separation performance. The commercialised tubular membrane was dip-coated into Matrimid/NMP solution and then proceed with carbonisation process at the optimum condition with a heating rate of 2 K/min and under Argon gas flow rate at 200 mL/min at temperature of 1,123.15 K by using argon gas. The pure gas permeation tested for both CO2 and CH4 was carried out under room temperature at pressure controlled at 800 kPa. From the experimental results, the tubular membrane made of 15 wt % Matrimid performed the highest CO2/CH4 selectivity (87.34 %) as compared to the other membranes. The excellent performance obtained from the membrane could be attributed by the micropores formation, where the chain of the polymer had increased its packing density. Thus, membrane porosity can be increased by increasing the polymer concentration in the solution.

Matrimid-based carbon tubular membrane: Effect of carbonization environment

Among gas separation materials, carbon membrane exhibits the most interesting performance in terms of selectivity, stability, and gas permeance. By controlling and optimizing carbonization environment, excellent gas separation performances can be achieved. In this study, tubular supported carbon membrane was prepared using Matrimid as polymeric precursor. In order to produce high performance carbon membrane, the effect of carbonization conditions on the gas permeation properties was investigated. The polymer solution was coated on the surface of the tubular support by using dip-coating method. Carbon membranes were fabricated by heat treatment process under controlled carbonization environments; Ar or N2. Pure gas permeation tests were performed using CO2, CH4, and N2 at room temperature with pressure 8bar. Based on the results, the highest CO2/CH4 and selectivity of 87.34 and CO2/N2 selectivity of 79.60 were obtained by carbon membrane carbonized under Ar gas. Despite the higher carbonization temperature, the carbonization under Ar created more permeable pores as compared to N2 environment.

Gas Permeation Study of Carbon Tubular Membrane by Manipulating Carbonization Temperature Profile

Membrane-based separation technology has been widely applied for large-scale industrial CO2 capture due to its lower energy consumption and low pollutant production compared with other conventional techniques. The desirable properties in high performance gas separation membranes involve steps that must carefully be designed and controlled. This study investigates the role of carbonization temperature in the fabrication and performance analysis of carbon membranes prepared from polyimide. A commercial polyimide, Matrimid® 5218, was coated on the surface of ceramic tube to produce supported polymer membrane. The prepared polymer membrane was then carbonized under nitrogen atmosphere to produce supported carbon membrane for CO2/CH4 separation. The resulting carbon tubular membrane separation performance was evaluated using pure gas permeation test. Results showed that the suitable carbonization temperature for Matrimid-based carbon tubular membrane was at 850 °C. The highest selectivity for CO2/CH4 of 82.47 was obtained from carbon tubular membrane prepared at 850 °C.

Matrimid‐based carbon tubular membranes: The effect of the polymer composition

ABSTRACTIn this article, we present a development study of new membrane materials and enhancements of productive membranes to improve the current performance of polymeric membranes. Carbon membranes are a promising material for this matter as they offer an improvement in the gas‐separation performance and exhibit a good combination of permeability and selectivity. Carbon membranes produced from the carbonization of polymeric materials have been reported to be effective for gas separation because of their ability to separate gases with almost similar molecular sizes. In this study, a carbon support membrane was prepared with Matrimid 5218 as a polymeric precursor. The polymer solution was coated on the surface of a tubular support with the dip‐coating method. The polymer tubular membrane was then carbonized under a nitrogen atmosphere with different polymer compositions of 5–18 wt %. The carbonization process was performed at 850°C at a heating rate of 2°C/min. Matrimid‐based carbon tubular membranes were fabricated and characterized in terms of their structural morphology, thermal stability, and gas‐permeation properties with scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and a pure‐gas‐permeation system, respectively. Pure‐gas‐permeation tests were performed with the pure gases carbon dioxide (CO2) and N2 at room temperature at a pressure of 8 bar. On the basis of the results, the highest CO2/N2 selectivity of 75.73 was obtained for the carbon membrane prepared with a 15 wt % polymer composition. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42394.

Separation of CO2/CH4 through Carbon Tubular Membranes: Effect of Carbonization Temperature

Carbon membranes have received much attention as advance materials in the gas separation technology due to their superior gas permeation performance and thermal and chemical stability. In order to increase the mechanical strength of the membrane, supported carbon membrane were produced using ceramic tube as support layer. Carbon tubular membranes were produced by carbonizing polymeric tubular membrane under different process parameter. In this study, carbon tubular membranes originating from Matrimid were prepared and characterized n term of its gas permeation properties. The preparation method involved dip-coating of the ceramic tubes with a Matrimid-based solution. The carbon tubular membranes were obtained by carbonization of the resultant polymeric tubular membrane under Argon gas flow in the horizontal tube furnace. The effects of the carbonization temperature on the gas permeation performance were investigated. Pure gas permeation tests were performed using CO2 and CH4 at room temperature with pressure 8 bars. The permeance and selectivity data indicate that the highest CO2/CH4 selectivity of 87.30 was obtained for carbon tubular membrane prepared at carbonization temperature of 850 ºC.

Gas Permeation Properties and Characterization of Polymer Based Carbon Membrane

Membrane gas separation is a forthcoming technology that advertised a great commercial potential in diverse industrial applications. Consequently, membrane-based natural gas processing has been among the fastest growing segments of the economic growth. The turbostratic structure of carbon membranes has been affirmed to accommodate with good separation selectivity for permanent gases. With that, the most auspicious technique acquired is by controlling the carbonization temperature during the carbon membrane fabrication. In this study, polymer-based carbon tubular membranes have been fabricated and characterized in terms of its structural morphology and gas permeation properties. Polyimide (Matrimid 5218) was used as a precursor for carbon tubular membrane preparation to produce high quality of carbon membrane via carbonization process. The polymer solution was coated on TiO2 –ZrO2 tubular tubes (Tami) by using dip-coating method. The polymer tubular membrane was then carbonized under Nitrogen atmosphere at 600, 750, and 850 ◦C. The structural morphology of the resultant carbon membranes was analyzed by means of scanning electron microscope (SEM). Pure gas permeation tests were performed using CO2 and N2 gases at 8 bars and room temperature. Based on the results, the highest CO2/ N2 selectivity of 79.53 was obtained for carbon membrane prepared at 850 oC.

Effect of impregnation on the pore structure of a tubular carbon membrane

Effect of impregnation on the pore structure of a tubular carbon membrane

Effect of impregnation on the pore structure of a tubular carbon membrane

To adjust and control the porous structure in the inner face of a tubular carbon membrane (TCM), impregnation methods were used, and the effects of impregnation on the pore size distribution were analyzed by adjusting impregnant concentrations and impregnation times. SEM images show that the impregnation treatment can repair the pore defects on the TCM surface. Data on the micropore size distribution indicate that the pore size of the TCM becomes smaller and its distribution becomes narrower with increasing impregnant concentrations and impregnation times, which indicates that impregnation conditions can be used to adjust the pore size and structure of the TCM.

Preparation and performance of carbon composite membranes with ordered mesopores

An ordered mesoporous carbon (OMC) was synthesized by the soft templating method using resorcinolformaldehyde as carbon source, and Pluronic F127 and F123 as templates. The carbon composite membrane was prepared by coating the precursors under optimum conditions on the outer surface of a tubular carbon membrane produced from blended coals, followed by carbonization to remove the template and convert the precursors to carbon. The influence of synthesis conditions such as kinds and quantities of the templates and catalysts on the structure and performance of the OMC were investigated by TEM, SEM and XRD. Results indicated that an optimized OMC with a wellordered pore structure and high permeation flux was synthesized under catalysis of HCl, F127/resorcinol molar ratio of 0.0081 and reaction temperature at 30℃. The largest pore size of carbon membranes decreased from 0.530μm for the tubular carbon membrane to 0.299μm for the composite membrane. The N2 permeability of the composite membrane reached 1.18·10-8m3·m-2·s-1·Pa-1, which was four times that of the conventional soft coalbased carbon membrane.