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Effects of coagulation bath temperature on the membrane formation mechanism and the morphologies of the formed membranes were studied. The binodal and spinodal lines in the phase diagrams of water/ DMAc/Poly(vinylidene fluoride) (PVDF) were calculated based on the thermodynamics equations of membrane formation, and the gel phase boundaries of the systems at 258C and 608C were determined via cloud point measurement. The obtained ternary phase diagrams of water/DMAc/PVDF contain three regions: the one-phase region, the liquid-liquid two-phase region, and the gel region. In the phase diagrams, the liquid-liquid demixing line (binodal) is located inside the gelation line. At low temperature, there exists a wide region between gelation line and binodal line. Gelation could occur in the absence of liquid-liquid demixing, and becomes the dominant membrane formation mechanism. At high temperatures (608C), however, the gelation line approaches the binodal line, which results in a much smaller gelation zone. The kinetics of the solvent out-flux and water influx were enhanced, liquid-liquid demixing is the dominant mechanism. The membrane formation mechanisms at different temperature were confirmed by the light transmission measurements during membrane forming process and the morphologies of the membranes examined by SEM imaging.

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Cyclohexanol is an organic chemical intermediate product widely used in chemical<br /> industry and commonly produced by cyclohexene hydration. Because of the low mutual<br /> solubility of cyclohexene and water, the reaction is limited by chemical equilibrium,<br /> which has the disadvantage of low conversion of cyclohexene. In this paper, the hydration reaction of cyclohexene catalysed by A-36 cation exchange resin catalyst was analysed by Aspen Plus V8.6 simulation software in the presence of isophorone as cosolvent.<br /> The process model of synthesising cyclohexanol by catalytic distillation was verified by<br /> process experiments. The simulation experiments were carried out using the process<br /> model, and suitable operating conditions of the catalytic distillation column were obtained. These are: ketene feed ratio 1.5, alkene/water ratio 0.5, distillation stage trays 5,<br /> reaction stage trays 12, stripping stage trays 6, cyclohexene feed at the 18th tray, water<br /> and isophorone feed at the 5th tray, reflux ratio 3, feed ratio (D/F) 0.25. Under these<br /> operating conditions, the conversion of cyclohexene can reach 40.63 %.

BACKGROUND Methyl tert‐butyl ether (referred to as MTBE) is harmful to the environment and hence its use is limited in China. To avoid the waste of isobutylene as MTBE raw material and improve the utilization rate of isobutylene in mixed C4 fraction, supported Fe(NO3)3/β molecular sieve catalysts with different active components were prepared by the equal volume impregnation method. The catalysts were analyzed by X‐ray diffraction (XRD), Thermogravimetric analysis (TG), Temperature programmed desorption of NH3, Brunauer–Emmett–Teller analysis and scanning electron microscopy, and the catalytic performance of catalysts with mixed C4 fractions as raw materials and different active component loadings for selective oligomerization of isobutylene was investigated in a fixed bed reactor. RESULTS The results show that the catalyst has the best catalytic performance when the active component loading was 6%, the reaction temperature was 60 °C, the reaction pressure was 1 MPa and the reaction space velocity was 1.5 h−1. CONCLUSION The conversion rate of isobutylene was >90%, the selectivity of C8 olefin was ≈80% and there was almost no loss of n‐butene. © 2021 Society of Chemical Industry (SCI).