Using Pebax-1074/ZIF-7 mixed matrix membranes for separation of CO2 from CH4

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.     

Separation of CO2 from CH4 using a synthesized Pebax-1657/ZIF-7 mixed matrix membrane

In this study, ZIF-7 nanoparticles were first synthesized and then incorporated into polyether-block-amide (Pebax-1657) matrix with different loadings to prepare mixed matrix membranes. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses were employed to recognize crystalline structure and chemical bonds variations of the ZIF-7 nanoparticles, respectively. Morphology of the membrane exhibited that the best performance was observed using FESEM analysis. The CO₂ and CH₄ permeation experiments were carried out at temperature and pressure of 30°C and 2.5 bar, respectively. The gas permeation results indicated that the mixed matrix membranes have higher efficiencies for CO₂/CH₄ separation compared with the neat membranes.     

Applying Pebax-1657/ZnO mixed matrix membranes for CO2/CH4 separation

Abstract

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.     

Laboratory investigation of carbon dioxide separation from methane using a PES/Pebax 1657 composite membrane

Removal of carbon dioxide from methane is a critical issue in the gas sweetening and treatment units. The aim of this study is to investigate the capability of PES/Pebax composite membrane in order to CO₂ removal from the CH₄. In this regard, permeability values of both carbon dioxide and methane have been measured. The ranges of temperature and pressure used for pure gases experiments were 20–50°C and 2.5–10 bar, respectively. Moreover, influence of CO₂ concentration on the CH₄ permeability and its selectivity was studied. Results indicated that the pressure and temperature have significant influence on permeability and selectivity. In addition, for the gas mixtures, experiments were carried out at 5 bar and 35°C. Results also indicated that at higher CO₂ concentrations the CO₂ permeability increased significantly.     

金属有机框架膜材料用于CO2分离过程的研究进展

金属有机框架材料(MOFs)具有孔隙率高、比表面积大、孔道可调节、结构多样等特点,将其添加到高分子膜中,可显著提升膜材料对CO₂的透过性和选择性。综述了近年来MOF膜材料用于CO₂分离过程的研究进展:①介绍了MOF膜材料的CO₂分离机理和合成工艺;②总结了几种主要的MOF膜材料在CO₂分离过程中的应用研究进展;③提出了MOF膜材料在CO₂分离领域的发展方向。      

氨基碳点/聚酰亚胺混合基质膜的制备及CO2分离性能研究

将水热合成法制备的氨基碳点与聚酰亚胺复合得到混合基质膜。通过SEM、FT-IR、XRD和DSC考查了氨基碳点掺杂质量分数对混合基质膜形貌和结构的影响。氨基碳点表面的氨基可以提供碱性环境,同时增加了膜内的自由体积,促进CO₂传递。当氨基碳点掺杂质量分数为0.3%时,混合基质膜的CO₂分离性能最佳,其CO₂、CH₄、N₂渗透通量分别为85.87 barrer、1.69 barrer、2.62 barrer,CO₂/CH₄、CO₂/N₂选择性分别为50.81和32.77。      

Effect of temperature on gas transport properties of supported ionic liquid membranes

The separations of the CO₂/N₂ and CO₂/CH₄ gas pairs using supported ionic liquid membranes (SILMs) with the immobilized ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate (bmim[BF₄]) and 1-butyl-3-methylimidazolium bis(2-ethylhexyl)sulfosuccinate (bmim[doc]) have been compared. The temperature dependences of the gas permeability, diffusion, and solubility coefficients have been obtained experimentally, and the temperature dependence of selectivity has been calculated. It has been found that the selectivity of membranes based on bmim[BF4] slightly decreases with temperature and the separation selectivity of CO₂/N₂ and CO₂/CH₄ systems on the membranes impregnated with bmim[doc] is almost independent of temperature.     

人工裂缝参数对CO2-ESGR中CO2封存和CH4开采的影响

目的 页岩储层中的裂缝系统对CH₄产量和CO₂封存量有着重要的影响,不同的储层地质特征有其对应的最优压裂方案。对鄂尔多斯盆地延长组页岩储层人工裂缝参数对CO₂封存和CH₄开采的影响进行分析。方法 基于鄂尔多斯盆地延长组页岩储层地质条件建立了页岩基质-裂缝双孔双渗均质模型,分析CO₂增强页岩气开采技术(CO₂-ESGR)中人工裂缝半长、裂缝宽度、裂缝高度、裂缝间距和裂缝数量对CO₂封存量和CH₄产量的影响。结果 CO₂封存量和CH₄产量与裂缝半长、裂缝宽度和裂缝高度呈正相关,其中裂缝宽度的影响最大,从5 mm增加到25 mm时,最多可使CO₂封存量和CH₄产量分别增加112.69%和87.11%。裂缝间距和裂缝数量增加可提高CO₂封存量和CH₄产量,但水平井长度相同时裂缝数量增加对CO...     

Enhanced Natural Gas and Condensate Recovery by Carbon Dioxide and Methane Flooding

Abstract

The authors quantitatively investigates the recovery efficiency, pattern behavior, and relative permeability of (a) condensate following supercritical carbon dioxide (CO₂) injection, methane (CH₄) injection, and the injection of their mixtures; and (b) natural gas of various compositions following pure supercritical CO₂ injection. A high-pressure high-temperature experimental laboratory was established to simulate reservoir conditions and to perform relative permeability measurements on sandstone cores. This work is part of an integrated enhanced natural gas and condensate recovery project conducted for a local reservoir in Western Australia. This data will help the operators develop operational and design strategies for their present and future EOR projects.     

Study of Separation Behavior of Activated and Non-Activated MOF-5 as Filler on MOF-based Mixed-Matrix Membranes in H<Subscript>2</Subscript>/CO<Subscript>2</Subscript> Separation

In this study, cubic and tetragonal structures of MOF-5 (C-MOF-5 and T-MOF-5) were successfully synthesized, characterized and incorporated into cellulose acetate (CA) polymer matrix in the range of 6, 9 and 12 wt % to fabricate mixed matrix membranes (MMMs). The effects of smaller pore size of T-MOF-5 and more ZnO molecules in T-MOF-5, on the H₂ and CO₂ permeation properties of C-MOF-5/CA and T-MOF-5/CA MMMs were investigated. The all novel MMMs were prepared using the solution casting method and characterized by FTIR, TGA and SEM. SEM images as well as results of FTIR and TGA analyses confirmed good adhesion between both MOF-5s and CA matrix. Addition of both C-MOF-5 and T-MOF-5 into the CA improved the gas transport properties of the CA, especially in H2 separation. The H₂/CO₂ selectivity continued the increasing trend at 9 wt % and did not significantly reduce even at 12 wt % due to good adhesion between both MOF-5s and CA. The highest H₂/CO₂ selectivity was obtained at 12 and 9 wt % loading of C-MOF-5 and T-MOF-5, respectively. By changing the filler from C-MOF-5 to T-MOF-5, the increasing and reducing of adsorption site of H₂ and CO₂ (respectively), and also reducing in pore size, caused the appearance of H₂ permeability to not change much but the CO2 permeability to reduce. Accordingly, the H₂/CO₂ selectivity in all T-MOF-5/CA MMMs is higher than that in all C-MOF-5/CA MMMs. According to obtained results, the activated MOFs (i.e., C-MOF-5 in this study) are not always the best choices for separation process.     

Effects of Impregnation Solvents on Catalytic Performance of Co-Ru-ZrO2/γ-Al2O3 Catalyst for Fischer-Tropsch Synthesis

Abstract

Used ZrO₂ modified γ-Al₂O₃ as support, Co-Ru catalysts were prepared by incipient impregnation method. The effects of impregnation solvents on the performances of catalysts were examined. The catalyst was prepared with ethanol solution and high Co dispersion was obtained, exhibiting highest activity of CO hydrogenation, very low methane selectivity, and high heavy hydrocarbon C₅ ⁺ selectivity. The catalysts were prepared with aqueous solution and methanol solution, and the reaction behaviors were similar. The solvent isopropanol caused the lowest catalytic activity and highest methane selectivity. Increasing the reaction temperature enhanced the CO hydrogenation rate, and the CO conversion slightly increased the CO₂ selectivity and favored the formation methane and light hydrocarbons, while the chain growth probability decreased. For the catalyst prepared with ethanol, the CO conversion, the CH₄ selectivity, and the C₅ ⁺ selectivity were 94.16%, 5.65%, and 88.2%, respectively, and the chain growth probability was 0.87 at 493 K, 1.5 MPa, 800 h^?1, and n(H₂):n(CO) = 2.0 in feed.     

Hybrid Gas Separation Membranes Containing Star-Shaped Polystyrene with the Fullerene (C<Subscript>60</Subscript>) Core

A physicochemical study of novel hybrid polymer membranes based on polyphenylene oxide with a star-shaped modifier incorporated into the matrix has been conducted, and the transport properties of the membranes in the gas separation process have been studied. Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) has been selected as the polymer matrix because of the low cost and high mechanical strength of this material. Star-shaped macromolecules (up to 5 wt %) containing six polystyrene arms grafted onto a fullerene(C₆₀) central core have been used as the filler. The structure and physical properties of the resulting membranes have been characterized by scanning electron microscopy, membrane density measurements, differential scanning calorimetry, and thermogravimetric analysis. Film surface has been studied by contact angle measurements. The gas separation properties of the membranes have been studied by the barometric method for the following individual gases: H₂, O₂, N₂, and CH₄. Data on the separation properties have been plotted as a Robeson diagram to compare with published data. It has been shown that the incorporation of star-shaped polystyrene into the PPO matrix leads to an improvement of the separation efficiency for selected gas pairs and an increase in selectivity compared with that of the unmodified membrane.     

Gas separation characteristics of new membrane materials based on poly(ethylene glycol)-crosslinked polymers and ionic liquids

Gas transport characteristics (permeability and diffusion and solubility coefficients for CO₂, O₂, N₂, H₂) of new crosslinked membrane materials synthesized by copolymerization of poly(ethylene glycol) dimethacrylate and poly(ethylene glycol) methyl ether methacrylate in the presence of various ionic liquids have been studied. Comparison of the characteristics of specimens with and without ionic liquids has revealed that the presence of ionic liquids enhances the permeability of the membranes, especially to CO₂. It has been shown that the enhancement of the CO₂ permeability of films incorporating ionic liquid is due to an increase in CO₂ solubility and the increase in selectivity for pairs of gases containing CO₂ is determined by thermodynamic selectivity of separation.     

Gas permeability of homogeneous and composite membranes based on poly(trimethylsilylpropyne)/poly(vinyltrimethylsilane) blends

Gas transport properties of membranes based on a blend of two silicon-hydrocarbon polymers, poly(trimethylsilylpropyne) (PTMSP) and poly(vinyltrimethylsilane) (PVTMS), have been investigated. The N₂ and CO₂ permeability of the membranes decreases by two orders of magnitude, and CO₂/N₂ selectivity increases about threefold with increasing PVTMS content in the blend from 0 to 100%. The effect of the volume contraction of the membranes has been found. The results of the experiments and calculations showed that the membrane properties throughout all the range of concentrations are in good agreement with the single-phase blend permeability model. The results of the research open the possibility of preparing PTMSP/PVTMS membranes with stable gas separation properties combining a high permeability of PTMSP and a rather high selectivity of PVTMS.     

Percolation of composite poly(vinyltrimethylsilane) membranes with carbon nanotubes

Recent years have seen a flurry of activity in research on the use of nanoparticles to improve the properties of polymeric membranes. It is known that the change in the macroscopic properties of these hybrid materials is associated with the parameters of the cluster of incorporated nanoparticles. The percolation threshold is higher than 15 vol % for the spherical particles and decreases with the increasing aspect ratio of the embedded nanoparticles of another shape. The paper presents the results of study on the permeability of gases (N₂, O₂, CH₄ and C₃H₈) and a test liquid (ethanol) through hybrid membranes based on the glassy polymer poly(vinyltrimethylsilane) (PVTMS) with embedded multiwall carbon nanotubes (MWCNT) with a concentration of 0.3–3 wt %. It has been found that the permeability of gases and liquids alters at MWCNT concentrations above 0.4 wt %, which corresponds to the percolation threshold for the given particles as proved by calculations. In addition, the gas permeability coefficients measured indicate a change in the transport mechanism and selectivity of the membrane.     

Double Action of Cr3+ Gel on Modifying Profile and Removing CaCO3 in ASP Flooding

Abstract

To decrease fluid emulsification and system scale caused by NaOH/surfactant/polymer flooding, a pilot test of Na₂CO₃/surfactant/polymer flooding was developed in Daqing Oilfield. The results show that the two problems mentioned above were controlled, but scale in the injecting system is becoming a new technical problem and the scale aggravates reservoir heterogeneity. By analyzing the scaling mechanism and the properties of the profile control agent, the study presents technique of Cr³⁺ polymer gel for improving the fluid sucking profile of an injection well in Na₂CO₃/surfactant/polymer flooding. The optional formula, property evaluation, and compatibility condition between Na₂CO₃/surfactant/polymer flooding and polymer gel were studied, and a pilot test was used to judge the availability of Cr³⁺ polymer gel in 2-1-P56 well of Daqing Oilfield. The study shows that polymer gel functions include scavenging and blanking off high permeability zone. The scale of the instrument of injection, pipes, and well wall is thoroughly explained. The fluid entry in the high-permeability layer decreased from 100 to 64.9%, and fluid entry in the low-permeability layer increased from 0 to 35.1%. The profile control of the injection well was effectively improved.     

Effect of Pd–Ru alloy membrane thickness on H<Subscript>2</Subscript> flux from steam reforming products

The influence of the thickness of a Pd–Ru alloy membrane on the H₂ flux from binary mixtures containing about 5 and 20% CO, CO₂, CH₄, and steam has been studied. It has been shown that with a decrease in the membrane thickness from 30 to 10 μm, the negative influence of these impurities on the H₂ flux increases. In experiments with pure H₂, it has been established that a decrease in the membrane thickness does not affect the nature of the rate-limiting step in the H₂ flow mechanism. The values for the effective activation energy of the H₂ permeability of the 30- and 10-μm membranes are 13.6 and 23.4 kJ/mol, respectively. A mathematical model describing the flow of hydrogen from binary mixtures through membranes of various thicknesses with varying temperature and pressure is proposed.     

A novel hybrid material based on polytrimethylsilylpropyne and hypercrosslinked polystyrene for membrane gas separation and thermopervaporation

To improve the membrane permeability and separation properties in gas separation processes and thermopervaporative (TPV) recovery of butanol from model fermentation mixtures, hybrid membranes based on polymers with an extremely high free fractional volume—polytrimethylsilylpropyne (PTMSP) and hypercrosslinked polystyrene (HCL-PS)—have been first prepared and experimentally studied. The composite membranes have been fabricated using the commercial sorbent Purolite Macronet MN-200 exhibiting high sorption capacity for organic solvents. It has been found that in the hybrid membranes, HCL-PS sorbent particles are nonuniformly distributed throughout the volume: they are located in the surface layer of the membrane. It has been shown that the introduction of a small amount of a modifying component (0.5–1.0 wt %) into the PTMSP matrix improves the time stability of transport properties and increase by a factor of 1.5–2 the permeability coefficients of the material to light gases (N₂, O₂, CO₂, CH₄) and butane vapor. It has been found that hybrid PTMSP/HCL-PS membranes have higher separation factors than those of PTMSP membranes in the TPV separation of a butanol/water binary mixture.     

Modelling of CO2 capture and separation from different gas mixtures using semiclathrate hydrates

In this work we present a model for predicting hydrate formation condition to separate carbon dioxide (CO₂) from different gas mixtures such as fuel gas (H₂+CO₂), flue gas (N₂+CO₂), and biogas gas (CH₄+CO₂) in the presence of different promoters such as tetra-n-butylammonium bromide (TBAB), tetra-n-butylammonium chloride (TBAC), tetra-n-butylammonium fluoride (TBAF), tetra-n-butyl ammonium nitrate (TBANO₃), and tetra-n-butylphosphonium bromide (TBPB). The proposed method was optimized by genetic algorithm. In the proposed model, hydrate formation pressure is a function of temperature and a new variable in term of Z, which used to cover different concentrations of studied systems. The study shows experimental data and predicted values are in acceptable agreement.     

Membrane separation of gaseous C1-C4 alkanes

The separation of various gaseous hydrocarbons with the aid of polymer membranes is considered; attention is focused on the separation of gaseous C₁–C₄ alkanes, which are the components of natural gas and associated petroleum gases. It is noted that a practically important property of membrane materials is the thermodynamic selectivity of a membrane, which makes it possible to enrich a permeate with heavier alkanes. Up to this point, polyacetylenes exhibited the best transport parameters for the solution of this problem. The second experimental section of this paper describes a study of the separation of CH₄ + C₄H₁₀ binary mixtures on films based on additive poly[3-(trimethylsilyl)tricyclononene-7]. It is demonstrated that this highly permeable saturated glassy polymer exhibits thermodynamic selectivity in experiments with both the individual gases (CH₄ and C₄H₁₀) and their mixtures and provides fivefold butane enrichment of a permeate. The test polymer and others additive Si-containing norbornene polymers are of interest as membrane materials for the separation of hydrocarbon gases.