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Determining an optimum catalyst for liquid-phase dehydration of methanol to dimethyl ether
, Article Applied Catalysis A: General ; Volume 349, Issue 1-2 , 2008 , Pages 6-12 ; 0926860X (ISSN) ; Kazemeini, M ; Aghaziarati, M ; Sharif University of Technology
2008
Abstract
The liquid-phase dehydration of methanol to dimethyl ether was investigated over various materials including synthetic zeolites, namely, ZSM-5, Y, Mordenite, Ferrierite and Beta as well as silica and alumina. The key characters investigated were the Si/Al ratio and cation exchange. The results showed that the Mordenite zeolite exchanged with H+ exhibited the highest activity in dehydration of methanol. After finding the most active catalyst, the Mordenite zeolite was modified with Cu, Zn, Ni, Al, Zr, Mg and Na via wet-impregnation method to further improve its selectivity, and characterized by AAS, XRD, NH3-TPD, NH3-FT-IR and BET surface area techniques. It was found that these materials...
Effect of SAPO-34's composition on its physico-chemical properties and deactivation in MTO process
, Article Applied Catalysis A: General ; Volume 364, Issue 1-2 , 2009 , Pages 48-56 ; 0926860X (ISSN) ; Farhadi, F ; Khorasheh, F ; Sahebdelfar, S ; Asadi, M ; Feng, Y. Z ; Sharif University of Technology
2009
Abstract
Several SAPO-34 samples with different Si/Al ratio (0.05-0.5) of synthesis gel were prepared hydrothermally at crystallization temperature of 190-215 °C. The products were characterized by XRD, SEM/EDX, NH3-TPD, FT-IR and nitrogen adsorption techniques. EDX data showed a deviation of elemental composition of products with respect to the Al, Si, and P from that of the gel mixture, but the increasing trend of Si/Al ratio of the products was confirmed. According to XRD and SEM results, crystallinity of samples increased with Si/Al ratio up to the low to medium range of ca. 0.13. However, a reduction in the crystallinity was observed with further increase of the silicon content of the synthesis...
Influence of adding a modified zeolite-Y onto the NiMo/Al2O3 catalyst utilized to produce a diesel fuel with highly reduced sulfur content
, Article Microporous and Mesoporous Materials ; Volume 332 , 2022 ; 13871811 (ISSN) ; Kazemeini, M ; Soltanali, S ; Rashidzadeh, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In order to make a Na–Y zeolite with Si/Al ratio of 2.27 more acidic with a higher volume of mesopores, a combination of different and consecutive methods including; chemical (i.e.; utilizing different compounds, such as NH4F and EDTA) and thermal/hydrothermal (i.e.; implementing calcination/steaming) methods, were employed for modification and dealumination. The combination of acidic-hydrothermal dealumination method led to a further structural collapse compared to that of the acidic calcination. In comparison with the other dealumination methods, the fluorination strategy (i.e.; utilizing NH4F) resulted in a zeolite with higher crystallinity, acidity, and specific surface area. The...