Sharif Digital Repository

It is well known that the direct synthesis of Di-Methyl Ether (DME) from the Syngas is highly exothermic; therefore, the temperature control for its production and hence a suitable heat transfer pattern is of ought most significance to the success of such process. As such, slurry bubble column reactor is recognized to be a more suitable means for this purpose than other choices including fixed bed reactor which is the usual type of system in which direct DME synthesis takes place. In other words, slurry reactors are desirable due to having suitable heat and mass transfer properties. In this research a mathematical model for direct synthesis of DME from synthesis gas in a slurry reactor for a... 

A number of HZSM-5 catalysts modified with 5 wt% Mg, Na, Zr, and Al as well as others modified with 5-60 wt% Zn prepared by wet impregnation. These materials were characterized by the NH3-TPD, XRF, and XRD analyses and tested in a slurry reactor to determine their activities in dehydration of methanol solution in kerosene. Reactions were carried out at 230°C and 19 bar for 4 h of residence time in the reactor. Results showed that in the first series, the catalyst modified with Zr and in the second series, the one modified with 10 wt% Zn led to the highest methanol conversion. It was deduced that elimination of strong acid sites and partial replacement of active cations in the HZSM-5 zeolite... 

Highly porous nanocrystalline alumina was synthesized using two different precipitation processes and precipitating agents, which were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and porosimetry analyses. Different precipitating agents yielded nanocrystalline alumina catalysts with different morphologies and textural properties. Batch precipitation using sodium bicarbonate at constant pH resulted in a highly porous nanocrystalline γ-alumina catalyst, having surface area of 351.47 m2 g-1, total pore volume of 1.68 cm3 g -1 and mean pore diameter of 19.17 nm. The mean crystallite size was also determined to be 3.8 nm, based on the XRD results. Catalytic...