•Graphene membrane with appropriate pore can separate propylene/propane efficiently.•The separation mechanism was investigated by adsorption and penetration process.•The PG membranes show stronger adsorption to propylene molecules.•The PG membranes show attractive potential energy wells to propylene molecules.•Propylene and propane molecules can “hurdle” across the graphene nanopores.Molecular dynamic (MD) simulation and first-principle density functional theory (DFT) calculation are applied to study the C3H6/C3H8 separation performance of porous graphene membrane. It was found that porous graphene membrane with appropriate pore size and shape can be employed to separate propylene and propane. Among the ten kinds of pores investigated, the graphene membrane with NH modified pores exhibit extremely superior selectivity for propylene while maintaining high permeance. According to the study on adsorption mechanism, porous graphene (PG) membranes show preferential adsorption towards propylene mainly attributed to van der Waals interaction, which gives C3H6 molecules more chances to approach the pores. On the other hand, interaction energy and electron density by DFT demonstrate that the attractive potential energy well and the less pronounced overlap of PG membrane towards propylene molecules do facilitate their penetration through the pores. On the contrary, the case is totally different with propane. We anticipate that our work will accelerate the application of porous PG membrane in the C3H6/C3H8 separation.Download high-res image (290KB)Download full-size image

ABSTRACTThe TiO2 nanoparticles were incorporated into an ethyl cellulose (EC) matrix to improve the pervaporation (PV) performance of the membrane for gasoline desulfurization. The microstructures of different EC membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray and transmission electron microscopy. The PV experiments showed that the hybrid membrane of EC/TiO2 demonstrated an improved permeation flux (J) of 7.58 kg m−2 h−1 and a sulfur enrichment factor (α) of 3.13 in comparison with the pure EC membrane, with a J of 3.73 kg m−2 h−1 and an α of 3.69. In addition, the effects of the operating conditions, including the operating temperature, layer thickness, crosslinking time, feed flow rate, and feed sulfur content level, on the PV performance of the EC/TiO2 membrane were investigated. Under a 100 mL/min feed flow rate and a 85 μg/g sulfur content, J of the 10 μm thick membrane increased to 7.58 kg m−2 h−1 with α of 3.13 compared to the pure EC membrane (3.73 kg m−2 h−1, 3.69) at 80 °C with 30 min of crosslinking time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017: 134, 43409.

•Two polymers based on phenanthra-9,10-quinone were synthesized and characterized.•Both of the two polymers exhibit multichromic properties.•The structure of substitution influences electrochromic properties of the polymers.•One polymer had high optical contrast, the other exhibited excellent response time.Two novel monomers 2,7-bis(3-ethylthiophen-2-yl)-9,10-phenanthrenequinone (ETPQ) and 2,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9,10-phenanthrenequinone (DDPQ) were successfully synthesized via Stille cross coupling reaction. Meanwhile, the corresponding polymers PETPQ and PDDPQ were synthesized electrochemically and characterized carefully. Both polymer films displayed multi-colored electrochromism. The PETPQ film showed a yellow color at neutral state, and with the increase of the applied potential, its color switched from yellowish green to green, and then light blue, finally a blue color in the oxidized state was observed. The color of the PDDPQ film was red in its neutral state, and turned to blue in the oxidized state, in intermediate states, violet red and purple colors were observed. Moreover, the parameters (coloration efficiency, optical contrast and response time) of the two interesting polymers were all reasonable and satisfactory. The dual-type electrochromic device based on PETPQ film (or PDDPQ film) and PEDOT film was constructed and characterized as well. Both of them revealed excellent properties.This figure shows electrochromic properties of the two polymers.