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Polyimides with Bulky Groups: Synthesis, Characterization, and Physical Properties
Published in Andreea Irina Barzic, Neha Kanwar Rawat, A. K. Haghi, Imidic Polymers and Green Polymer Chemistry, 2021
Barnali Dasgupta Ghosh, Susanta Banerjee, Alexander Alentiev, Inga Ronova, Yuri Yampolskii
Chang et al. synthesized a series of PIs substituted with TPA to investigate the effect of the bulky substituents like methyl, N,N bisphenyl amine, and methoxy substituted N,N bisphenyl amine (Fig. 2.14) on their properties.79 All the PIs had good thermal stability associated with high softening temperatures (279–300°C), 10% weight loss temperatures in excess of 505°C in nitrogen. The substituted triphenyl amine containing PI can be used for gas separation as it reveals very good combination of gas permeability and permselectivity. The 4-methoxy substituted TPA-containing PIs (PI IV) showed better gas permeability (PCO2 = 12.97; PO2 = 2.94 Barrer) than that of the unsubstituted PIs (PI III) (PCO2 = 11.77; PO2 = 1.97 Barrer). Also, PI IV exhibited higher gas selectivity value of 32.43 for CO2/CH4 gas pair (Table 2.4).
2 Separation from Natural Gas
Published in Zeinab Abbas Jawad, 2 Sequestration and Separation, 2019
A.K. Zulhairun, N. Yusof, W.N.W. Salleh, F. Aziz, A.F. Ismail
One of the key issues is transforming these advanced membranes into a reliable design of industrial membrane modules with high surface area-to-volume ratio. Most studies have almost exclusively focused on dense flat sheet or thin film composite membrane morphologies. To put industrial applicability into perspective, consider a conventional CTA membrane with intrinsic permeability ca. 10 barrer gives of CO2 permeance of 100GPU when the membrane’s thickness is 100 nm. Imagine that if PIM-1 membrane of the same thickness could possibly be fabricated the CO2 permeance would reach up to 10,000 GPU. Therefore, it is of great interest to see the exciting development of these materials having ultra-thin skinned morphology which would revolutionize the technology for gas separation. Effort in fabricating asymmetric membrane comprising the advanced materials discussed in this chapter has been seen underway but may need to be further optimized and streamlined. Great challenge lies in the appropriate scaling-up from laboratory-scale hollow fiber membrane modules to industrial-scale modules, which requires a thorough understanding on the impacts of operating conditions (pressure, temperature, and concentration profiles) as well as fluid flow behavior at the membrane interfaces in the module. Scientific research conducted thus far has set exciting paths for unimaginable innovation and might lead to fruition of novel materials with astounding properties for addressing our industrial needs as well as mitigating global warning issues related to the emission of greenhouse gases into our environment.
Silica, Template Silica and Metal Oxide Silica Membranes for High Temperature Gas Separation
Published in Stephen Gray, Toshinori Tsuru, Yoram Cohen, Woei-Jye Lau, Advanced Materials for Membrane Fabrication and Modification, 2018
David K. Wang, João C. Diniz da Costa
The first generation of silica membranes was accompanied by fundamental studies on porous substrates and interlayers, silica sol-gel synthesis, and thin film coating methods in the 1980s. Several groups that greatly contributed to the first-generation development were Burggraaf at the University of Twente in the Netherlands, Cot at the European Institute of Membranes in France, Gavalas at the California Institute of Technology, Brinker at the University of New Mexico in the United States, and Nakao at the University of Tokyo in Japan. Major achievements appeared at the end of the first generation. Verweij’s group (de Vos and Verweij, 1998a; 1998b) at the University of Twente developed high quality silica membranes in clean rooms delivering He fluxes in the order of 1×10–6 mol m–2 s–1 Pa–1 and He/N2 permselectivities of ~100. This became the benchmark standard for silica membranes. A second achievement was the use of the chemical vapor deposition (CVD) method to prepare silica membranes. Nakao’s group (Nomura et al., 2005) developed a counter diffusion CVD method that led to silica membranes delivering H2/N2 permselectivities in excess of 1000, though lower H2 fluxes in the order of 1×10–7 mol m–2 s–1 Pa–1. During this first generation, high quality silica membranes were characterised by temperature-dependent flux of gases, thus complying with the model developed by Barrer (1990) for activated transport.
Applying Pebax-1657/ZnO mixed matrix membranes for CO2/CH4 separation
Published in Petroleum Science and Technology, 2019
Zahra Farashi, Navid Azizi, Reza Homayoon
After the volumetric flow-rate of a permeate gas was measured using a bubble flow meter, its permeability coefficient (Pi) in Barrer () was calculated employing the Eq. (1): Where, T, p, Δp, A, Qi, and l are feed temperature (K), permeate side pressure (cmHg), pressure difference between feed and permeate sides (cmHg), the membrane effective area (cm2), the permeate gas volumetric flow-rate (cm3/s) and the membrane thickness (cm), respectively. Additionally, the ideal CO2/CH4 selectivity is defined as the ratio of the permeability coefficient of CO2 to that of CH4 ()
Silver(I) N–heterocyclic carbene complex encapsulated in cellulose acetate membranes for hydrogen gas purification
Published in Journal of Coordination Chemistry, 2022
Vignesh Nayak, Prajwal Sherugar, Mahesh Padaki, B. M. Geetha, Srinivasa Budagumpi
Based on the values presented in Table 2, H2 gas has the maximum permeability through the pristine and composite membranes. H2 gas achieved 8.4 Barrer permeability for pure CA membrane and 13.7 Barrer is the highest permeability of H2, which is observed for CAAg01 membrane. CO2 achieved 3.5 Barrer permeability for CA membrane and this permeability was further increased with increased concentration of 2 in the membrane matrix. The highest CO2 permeability was observed for CAAg01 composite membrane i.e. 6.6 Barrer. Finally, for CH4, the permeability remained almost constant with 0.2 Barrer. However, a slight increase was noticed in the case of CAAg01 showing 0.3 Barrer. Thus, it can be observed that on increasing the composition to 0.1% of 2, there is an increase in permeability for all the gases over pure CA membrane. However, on further increase in dosage of 2 the permeability shows a decrease. This implies that higher complex composition decreases the mobility of the polymer chains and thus led to a decrease in the permeation efficiency. Hence, higher concentrations were not studied as the permeability decreased below the pristine CA membrane. Based on these results, the ideal selectivity of H2/CO2 showed a decreasing trend as 2 was added, with a value of 2.4 for pure CA which decreased to 2.1 and 2 for CAAg01 and CAAg02, respectively. Similarly, H2/CH4 and CO2/CH4 achieved selectivity values of 42 and 18, respectively, for pure CA. These selectivity values reached a maximum value of 65 and 32, respectively, for 0.2 wt%, and showed an increasing trend for H2 gas purification.
Influence of hydrogen sulfide on the efficiency of xenon recovery from natural gas by gas hydrate crystallisation
Published in Petroleum Science and Technology, 2019
Maria Sergeeva, Anton Petukhov, Ilya Vorotyntsev, Vladimir Malyshev, Vladimir Vorotyntsev
Critical condition for the gas hydrate phase formation (Barrer and Stuart 1957): where h is the ratio of the large/small gas hydrate cavities number in the gas hydrate unit cell (for CS-I h = 3.00 (Barrer and Stuart 1957)); m is the water molecules number per one the gas hydrate cavity (for CS-I m = 5.75 (Barrer and Stuart 1957)); C1i is the Langmuir constant for the small gas hydrate cavities, 1/Pa; C2i is the Langmuir constant for the large gas hydrate cavities, 1/Pa; is the partial pressure of i-gas, Pa.