Iranian Journal of Chemical Engineering (IJChE)

Abstract MXene membranes perform well in biofuel separation due to their excellent hydrophilicity, flexibility, and mechanical strength. For the first time, computational fluid dynamics was used to model the dehydration of ethanol through the pervaporation system by the MXene membrane. We discretized the momentum and continuity equations using finite element methods and predicted the mass transport. Experimental results and model data were in good agreement (less than 10 %). The feed velocity, feed concentration, and membrane thickness all had positive effects on the separation factors while the temperature had a decreasing effect. This model's efficiency has decreased by 35 % after increasing the feed flow rate by 10 times. In addition, the separation factor increases tenfold when temperature is raised from 25 to 70 °C.

Abstract ine"> Chabazite zeolite membranes were synthesized for their potential application in dehydration of natural gas. The membranes were prepared using secondary growth method on porous ·-alumina substrates. Hydrothermal treatment was applied for the synthesis of chabazite seeds. The membranes were synthesized at four temperatures of 100, 120, 140, and 160°C; and duration of 20 h. Separation performance of assynthesized membranes was evaluated through permeation ofwater vapor and methane as single gas. Moreover, the structure and morphology ofas-synthesized chabazite zeolite membranes as well as seeds were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS). The results revealed that the optimum temperature for the synthesis ofchabazite membranes is 140°C while at lower and higher temperatures, lower separation performances were observed. At the optimum synthesis temperature, an ideal selectivity of 23 was obtained for water vapor/methane, while a thin and integrated chabazite zeolite layer of about 5 m in thickness was synthesized over the surface ofalumina substrate.

Abstract Synthesis of Dimethyl ether from methanol was investigated over H-ZSM-5 and promoted H-ZSM-5 catalysts employing Mg, Na, Zr, Al and Zn components. All samples were characterized by AAS, BET, XRD and TPD analyses. Results of TPD
analysis indicated that the number of weak strength acid sites increased on the surface of Na, Zn and Mg modified H-ZSM-5, while the number of medium strength acid sites increased on the surface of Zr and Al modified H-ZSM-5. Zr- modified H-ZSM-5 zeolite exhibited higher activity (94%) and selectivity (99%) than other materials while all modified catalysts exhibited good stability. Ultimately, it was concluded that production of dimethyl ether from methanol occurred
on acidic sites with medium and/or weak strengths. In this direction, an optimum catalyst for dehydration of methanol to DME with high conversion, selectivity and stability was developed.