Intrinsic Kinetics Study of Dimethyl Ether Synthesis from Methanol on γ-Al₂O₃ Catalysts

Abstract

A series of commercially available γ-Al 2 O 3 samples were tested for vapor-phase dehydration of methanol to dimethyl ether (DME). The samples were characterized using X-ray diffraction (XRD), temperatureprogrammed desorption of ammonia (NH 3 -TPD), and Brunauer-Emmett-Teller (BET) surface area techniques. The catalysts were determined to be highly amorphous with similar porous structures. Catalyst screening tests were performed in a fixed-bed reactor under the same operating conditions (temperature, T ) 573 K; pressure, P ) 16 bar (gauge); weight hourly space velocity, WHSV ) 26.07 h -1 ). The influence of operation conditions on catalyst performance, as well as the stability of catalysts toward water, was also studied. It was determined that γ-Al 2 O 3 catalysts with acidic sites whose acidity is very weak and/or moderate exhibit the best catalytic performance and stability. A new kinetics expression was developed for the dehydration of methanol to DME. The kinetics was observed to fit the experimental data accurately. An activation energy of 57.7 kJ/mol was obtained for the catalyst with the best performance.

Modeling and operating conditions optimization of Fischer–Tropsch synthesis in a fixed-bed reactor

“…To achieve the isothermal conditions in a catalytic bed, the catalyst was diluted with an inert material (quartz). Axial temperature distribution was ensured using Mear's criterion [26], that is with L/d p > 50. Also, plug-flow was assumed for the gaseous feed.…”

Kinetic study of Fischer–Tropsch process on titania-supported cobalt–manganese catalyst

“…To achieve the isothermal conditions in a catalytic bed, the catalyst was diluted with an inert material (quartz), Axial temperature distribution was ensured using Mear's criterion [29,30] that is, with L/dp > 50. Also, plug-flow was assumed for the gaseous feed.…”

Synthesis of dimethyl ether (DME) by catalytic distillation

“…At present, DME is used as an aerosol propellant to replace chlorofluorocarbons (CFCs), which was found to harm the ozone layer of the atmosphere (Fortunately, it was reported on September, 2010 that ozone layer depletion has been halted; see http://www.cosmosmagazine.com/news/3742/ ozone-layer-depletion-has-stopped-say-scientists) (Mollavali et al, 2008;Xu et al, 1997). Furthermore, DME has a wide range of applications as a high-quality household fuel in place of liquefied petroleum gas (LPG) because its physical properties are similar to LPG (Song et al, 2008;Varisli and Dogu, 2008).…”