Water-stable ZIF-300/Ultrason(R) mixed-matrix membranes for selective CO2 capture from humid post combustion flue gas

Water stable mixed-matrix membranes (MMMs) were developed to help control the global warming by capturing and sequestrating carbon dioxide (CO2) from post-combustion flue gas originated from burning of fossil fuels.MMMs of different compositions were prepared by doping glassy polymer Ultrason(R) S 6010 (US) with nanocrystals of zeolitic imidazolate frameworks (ZIF-300) in varying degrees.Solution-casting technique was used to fabricate various MMMs to optimize their CO2 capturing performance from both dry and wet gases.The prepared composite membranes indicated enhanced filler-polymer interfacial adhesion,consistent distribution of nanofiller,and thermally established matrix configuration.CO2 permeability of the membranes was enhanced as demonstrated by gas sorption and permeation experiments performed under both dry and wet conditions.As compared to neat Ultrason(R) membrane,CO2 permeability of the composite membrane doped with 40 wt％ ZIF-300 nanocrystals was increased by four times without disturbing CO2/N2 ideal selectivity.In contrast to majority of previously reported membranes,key features of the fabricated MMMs include their structural stability under humid conditions coupled with better and unaffected gas separation performance.     

H2-selective mixed matrix membranes modeling using ANFIS,PSO-ANFIS,GA-ANFIS

The novel contribution of the current study is to employ adaptive neuro-fuzzy inference system (ANFIS) for evaluation of H₂-selective mixed matrix membranes (MMMs) performance in various operational conditions. Initially, MMMs were prepared by incorporating zeolite 4A nanoparticles into polydimethylsiloxane (PDMS) and applied in gas permeation measurement. The gas permeability of CH₄, CO₂, C₃H₈ and H₂ was used for ANFIS modeling. In this manner, the H₂/gas selectivity as the output of the model was modeled to the variations of feed pressure, nanofiller contents and the kind of gas, which were defined as input (design) variables. The proposed method is based on the improvement of ANFIS with genetic algorithm (GA) and particle swarm optimization (PSO). The PSO and GA were applied to improve the ANFIS performance. To determine the efficiency of PSO-ANFIS, GA-ANFIS and ANFIS models, a statistical analysis was performed. The results revealed that the PSO-ANFIS model yields better prediction in comparison to two other methods so that root mean square error (RMSE) and coefficient of determination (R²) were obtained as 0.0135 and 0.9938, respectively. The RMSE and R² values for GA-ANFIS were 0.0320 and 0.9653, respectively, and for ANFIS model were 0.0256 and 0.9787, respectively.     

Study on CO2 facilitated separation of mixed matrix membranes containing surface modified MWCNTs

Mixed matrix membranes (MMMs) for CO₂-facilitated separation were prepared by incorporating different surface-modified multiwalled carbon nanotubes (MWCNTs) in a fixed carrier membrane material. Polymer containing amino groups, poly(vinylalcohol-co-vinylamine) (VA-co-VAm) was synthesized as polymeric matrix. MWCNTs as well as MWCNTs surface-modified with  OH and  NH₂ were applied as nanofillers. The physical property, chemical structure, and membrane morphology were characterized by FT-IR, TG, XRD, DSC, CA, XPS, and SEM. The effects of content, functional group, temperature, and pressure on gas permselectivity were studied. Results show that the incorporation of nanofillers can effectively restrict the polymer chain packing and lead to low crystallinity. The MMMs exhibited higher CO₂ permselectivity than the pure polymeric membrane. For all the MMMs, the CO₂ permeance and selectivity increased with MWCNTs contents to a maximum and then decreased. MWCNT-NH₂ can be regarded as the most effective nanofiller. MMMs with 2.0 wt % MWCNT-NH₂ displayed the highest CO₂ permeance of 132 GPU and CO₂/N₂ selectivity of 74. Both CO₂ permeance and selectivity were decreased with feed gas pressure and temperature. The membrane exhibited good stability in the testing with the binary gas mixtures of CO₂/N₂ for 110 h under 0.54 MPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47848.     

PBI/Clinoptilolite mixed-matrix membranes for binary (N2/CH4) and ternary (CO2/N2/CH4) mixed gas separation

In this work, polybenzimidazole (PBI)-based mixed matrix membranes (MMMs) with natural zeolite were prepared and their transport properties for binary (N₂/CH₄) and ternary (CO₂/N₂/CH₄) mixed-gas separation were studied. The MMMs, were prepared with PBI as polymeric matrix and Mexican natural zeolite clinoptilolite enriched with cations of Ca²⁺ as filler. The thermal properties analysis of the PBI and MMMs studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicates that the MMMs membranes have Tg higher than 350°C and decomposition temperatures above 600°C compared with the pristine membranes. PBI membrane and MMMs were analyzed by X-Ray Diffraction (XRD) and the diffraction patterns showed the zeolite signals combine with the amorphous dome from the polymeric matrix. In addition, the perm-selectivity properties of the polymeric membranes and MMMs were tested with binary (N₂/CH₄; 10/90 mol%) and ternary (CO₂/N₂/CH₄; 5/10/85 mol%) gas mixtures at different pressure rates (50, 150 and 300 psi). The perm-selectivity properties of the MMMs membranes show an improvement in their values about 30% higher compared to the PBI polymeric membranes, favoring the permeation of CO₂ and N₂.     

Magnetic Mixed Matrix Membranes Consisting of PPO Matrix and Magnetic Filler in Gas Separation

Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and magnetic neodymium powder particles MQP-14-12 have been used for the preparation of magnetic mixed matrix membranes. Permeability diffusion and sorption coefficients of O₂, N₂, and synthetic air components were estimated for homogeneous and heterogeneous membranes using the Time Lag method based on dynamic experiments in a constant pressure system. The influence of magnetic field and magnetic powder particles on the gas transport properties of MMMs was studied. The results showed that the membrane permeation properties were improved with the magnetic neodymium particle filling. It was observed that the magnetic ethylcellulose and poly(2,6-dimethyl-1,4-phenylene oxide) membranes showed higher gas permeability, while their permselectivity and solubility were rather maintained or slightly increased. The results also showed that the magnetic powder addition enhanced gas diffusivity significantly in EC and PPO membranes.