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SAPO-34 molecular sieves have a high adsorption capacity in separation of CO2 from CO2/CH4 mixture. In this study, SAPO-34 was modified by different solutions at various operating conditions to enhance the removal of carbon dioxide from the methane gas. Modifications can change pore size and also Si/Al ratio in SAPO-34 and make changes in the acidity of the adsorbent via the ion exchange process. The effects of temperature and pressure on the separation were studied using the design of experiments. Finally, based on the results of the experimental optimization process applying central composite design (CCD) method, the highest yield of CO2 separation from the methane gas (95%) was obtained when using P-SAPO-34 sample at 17.4°C and 4.6 bar. [ABSTRACT FROM AUTHOR]

Membrane technologies as conservative approaches have absorbed much attention in chemical and petroleum engineering, recently. The current research presents the preparation of effectively mixed matrix membranes (MMMs) using polyether-block-amide (Pebax-1657) as a polymeric matrix and zinc oxide (ZnO) nanoparticles with various contents (0.0, 2.5, 5.0, 7.5, and 10.0 wt%) as a filler. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and field emission scanning microscopy (FESEM) were conducted to characterize the prepared membranes. The membrane performance was evaluated by caring out permeation experiments of the CO2 and CH4 at a pressure of 3 bar and temperature of 30 °C. Based on the obtained results, the CO2 permeability and ideal CO2/CH4 selectivity increased about 13 and 21%, respectively at 10.0 wt% loading of ZnO in the polymer matrix. [ABSTRACT FROM AUTHOR]

Membrane processes are economical techniques which have attracted many attentions in petroleum engineering particularly in the gas separation, recently. In this study, effective mixed matrix membranes were prepared using polyether-block-amide (Pebax-1074) as base polymer and ZIF-7 nanoparticles with different loadings as fillers. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and field emission scanning microscopy (FESEM) analyses were used to characterize the synthesized nanoparticles and membranes. To investigate performance of the membranes, permeation experiments of the CO2 and CH4 through the membranes were carried out at pressure of 3 bar and temperature of 30°C. The obtained results indicated that the mixed matrix membranes have higher CO2/CH4 selectivities compared to the neat membrane. [ABSTRACT FROM AUTHOR]

Membrane processes are economical techniques which have attracted many attentions in petroleum engineering particularly in the gas separation, recently. In this study, effective mixed matrix membranes were prepared using polyether-block-amide (Pebax-1074) as base polymer and ZIF-7 nanoparticles with different loadings as fillers. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and field emission scanning microscopy (FESEM) analyses were used to characterize the synthesized nanoparticles and membranes. To investigate performance of the membranes, permeation experiments of the CO2 and CH4 through the membranes were carried out at pressure of 3 bar and temperature of 30°C. The obtained results indicated that the mixed matrix membranes have higher CO2/CH4 selectivities compared to the neat membrane. [ABSTRACT FROM AUTHOR]

In this study, poly (ether-block-amide) (Pebax-2533) based mixed matrix membranes were prepared by incorporating various contents of synthesized zeolitic imidazole framework (ZIF-8) nanoparticles into the polymer matrix. The membranes were fabricated via a solution casting–solvent evaporation technique. The results of gas permeation through the membranes revealed that the addition of the ZIF-8 into the polymer matrix enhances both permeability and CO2/CH4selectivity values. As an example, for the mixed matrix membrane comprising 25 wt% of ZIF-8, CO2permeability and ideal CO2/CH4selectivity values are 269.73 Barrer and 9.31, respectively, while the corresponding values are 187.54 Barrer and 7.25 for the neat membrane. [ABSTRACT FROM AUTHOR]

In this study, permeation of carbon dioxide (CO2) and methane (CH4) through the polycarbonate/polyethylene glycol (PC/PEG) blend membrane was investigated. The effect of PEG content (0–5 wt%) on the permeability and selectivity was studied. Permeability measurements were carried out at pressures of 1–7 bar and at room temperature. The membranes were characterized by Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and density measurement. The results revealed that the PC/PEG blends are miscible/partially miscible without considerable micro-phase separation. The effect of PEG content and gas pressure on the diffusion and solubility of coefficients were also investigated and analyzed. It was concluded that the most influential parameter for the permeation is the diffusion coefficient of the gases. The permeability and selectivity decrease as the operating pressure and PEG content are increased. Furthermore, the results showed that the addition of 5 wt% of PEG into PC increases the CO2/CH4selectivity from 26.6 ± 0.99 to 40.9 ± 2.14 (more than 53%) at 1 bar. [ABSTRACT FROM PUBLISHER]

Biogas can be upgraded to biomethane through CO2removal as a sustainable replacement of natural gas. Membrane systems that are based on a two-step design have emerged as an attractive approach for the CO2removal. The objective of this work is to determine optimal membranes for this application by performing process simulation and techno-economic analysis. Practical membranes with the trade-off of CO2permeance and CO2/CH4selectivity on the Robeson’s upper bound are considered, and the membranes in the two steps are varied independently. Optimal membranes should have high CO2permeance with sufficient CO2/CH4selectivity (10–25) to achieve the lowest operating cost for the CO2removal. [ABSTRACT FROM AUTHOR]

The separation of CO2/CH4is reported in detail by using zeolitic imidazolate framework (ZIF-8) membrane which was prepared on 3-aminopropyltriethoxysilane modified Al2O3tube through microwave heating synthesis. Attributed to the preferential adsorption affinity of CO2over CH4and a narrow pore window of 0.34 nm, the ZIF-8 membrane shows high separation performances for the separation of CO2/CH4mixtures. For the separation of equimolar CO2/CH4mixture at 100°C and 2 bar feed (1 bar permeate) pressure, a CO2permeance of 1.02 × 10−8mol/m2· s· Pa and a CO2/CH4selectivity of 6.8 are obtained, which is promising for CO2separation. [ABSTRACT FROM PUBLISHER]

Removal of carbon dioxide (CO2) from natural gas is of importance because the existence of CO2in natural gas increases the cost of the sweetening process. In recent years, membrane technology has emerged as an attractive alternative in separating CO2from CH4due to its economical, efficient, and environmentally-friendly process. Here, we review the different types of membranes used in CO2/CH4gas separation. Zeolitic imidazolate frameworks (ZIFs) membranes are emphasized and ZIF-8 membranes are selected for further discussion due to their remarkable properties, including high chemical and thermal stability, facile and controllable pore apertures, and high CO2permeance. Different types of methods used for the synthesis of ZIF membranes and the challenges encountered in the growth of the membrane are summarized. Potential use of microwave technology in fabricating a continuous and low-defects ZIF membrane within a short period of time are discussed and highlighted. In conclusion, future direction and perspectives are indicated. [ABSTRACT FROM AUTHOR]

Impact of Si/Al ratio on the adsorption capacity and separation selectivity of CO2/CH4 in SAPO-34 has been investigated. SAPO-34 samples were synthesized with two Si/Al ratios (0.2 and 0.3). A batch adsorption volumetric apparatus was used to measure the adsorption equilibrium capacity and derive the equilibrium isotherms. The tests were performed in a wide range of pressure from normal to 3000 kPa and three levels of temperatures from 277 to 298 K. Results proved decreasing Si/Al ratio, from 0.3 to 0.2, improved CO2 separation from CH4. [ABSTRACT FROM AUTHOR]

Various technologies are now available to design engineers to condition raw natural gas to pipeline quality. Conditioning of natural gas involves the removal of acid gases like CO2 and H2S, besides water vapor. Among different separation methods available, membrane technology has emerged to be a viable and valuable option over conventional techniques like amine absorption, in view of its advantages such as economy, process safety and environmentally benign nature. Semi-permeable membranes were first employed in natural gas processing for more than 20 years. However, the technological breakthrough in the application of polymeric membranes to natural gas separation accelerated with the development of asymmetric membranes, which retain their selective characteristics, but after increased permeation rates as compared to their dense counterparts. Efforts to correlate the basic polymer structure with permeability and selectivity have resulted in the synthesis of novel polymers. Membranes for natural gas separation are most generally configured in the form of hollow fibers, capillaries or spirally wound elements, considering their intrinsic separation characteristics, process conditions and design parameters. This review addresses the current scientific and technological breakthrough that governs the field of application of membranes for natural gas separation. The performance of such membranes and the current research activity on CO2/CH4 separation are the main focus of this review. Potential membrane materials for further research in this area are also discussed [ABSTRACT FROM AUTHOR]