Dimethyl ether, diethyl ether & ethylene from alcohols over tungstophosphoric acid based mesoporous catalysts

Ciftci, Aysegul
Tokay, Kenan Cem
Sezgi, Naime Aslı
Doğu, Timur
Tungstophosphoric acid (TPA) incorporated silicate structured new mesoporous catalysts were synthesized following one-pot hydrothermal and impregnation procedures. Surface area of TPA@MCM-41, which was prepared by impregnating TPA into MCM-41, was two orders of magnitude higher than the surface area of pure TPA and this catalyst showed very high activity in dehydration reactions of both ethanol and methanol. Ethanol fractional conversion values reaching to 1.0 was obtained at 300 degrees C at a space time of 0.27 s.g/cm(3), over TPA@MCM-41. Diethyl ether selectivity showed a decreasing trend by increasing temperature from 180 to 400 degrees C in ethanol dehydration reaction. Ethylene yield values approaching to 100% were obtained at temperatures over 250 degrees C. DME yield passed through a maximum at about 200 degrees C with this catalyst, over which coke formation caused catalyst deactivation. One-pot hydrothermal synthesis procedure was very successful to synthesize a catalyst (TRC-W40) which did not lose any activity after repeated washing steps. This catalyst gave highly stable catalytic performance in dehydration of both ethanol and methanol. Well dispersed WOx clusters were formed within the mesoporous silicate matrix of this material. This catalyst showed very good activity in dehydration reactions of alcohols, giving 100% conversion in ethanol dehydration at 400 degrees C and 100% DME selectivity in methanol dehydration at temperatures less than 300 degrees C.


Dimethyl Ether Synthesis over Novel Silicotungstic Acid Incorporated Nanostructured Catalysts
Ciftci, Aysegul; VARIŞLI, DİLEK; Doğu, Timur (2010-01-01)
Dimethyl ether (DME), which is an excellent green diesel-fuel alternate with excellent clean burning properties, is synthesized by dehydration of methanol over novel solid acid catalysts, which are synthesized following a direct hydrothermal route and using silicotungstic acid (STA) as the active compound. These mesoporous silicate structured catalysts have surface area values of 108-393 m(2)/g, depending upon their W/Si ratio. These catalysts showed very high methanol dehydration activity and also very hig...
Pyrolysis of Polyethylene over Aluminum-Incorporated MCM-41 Catalyst
Aydemir, Bugce; Sezgi, Naime Aslı (2016-01-01)
Aluminum-containing MCM-41 catalysts were synthesized in this study by impregnation of aluminum into hydrothermally synthesized MCM-41. Aluminum was loaded into the porous framework of silica with different Al/Si ratios, using aluminum isopropoxide as the aluminum source. These catalysts exhibited Type IV adsorption-desorption isotherms and had a pore diameter of 2.4nm. Aluminum species were coordinated tetra- and octahedrally in the structure of catalysts. Diffuse Reflectance Fourier Transform Infrared Spe...
Synthesis of TPA impregnated SBA-15 catalysts and their performance in polyethylene degradation reaction
Aydemir, Bugce; Sezgi, Naime Aslı; Doğu, Timur (2012-08-01)
Tungstophosphoric acid (TPA)-containing mesoporous santa barbara amorphous (SBA)-15 materials were synthesized by impregnation of TPA into hydrothermally synthesized SBA-15. TPA was incorporated to the porous framework of silica with different W/Si ratios, using TPA hydrate as the acid source. The synthesized materials had a surface area range of 212-825 m2 g-1, depending on the TPA loading and exhibited Type IV adsorptiondesorption isotherms. Energy dispersive spectrometry and X-ray photoelectron spectrosc...
Facile synthesis of (4-nitrophenyl)thio-substituted 1- pyrrolines
Korkmaz, Esra; Zora, Metin; Department of Chemistry (2019)
The importance of heterocyclic compounds is enormous in synthetic organic chemistry due to their presence in bioactive molecules. Five-membered 1-pyrrolines are one of the most important classes of them. They have recently drawn great attention from synthetic chemists since they have a prominent role for the synthesis of a great number of pharmaceutical molecules. Therefore, there is intense research on their synthesis. In this project, we concentrated on the synthesis of (4-nitrophenyl)thio-substituted 1- ...
Enantioselective reduction of ketones with borane catalyzed by cyclic β- amino alcohols prepared from proline
Demir, Ayhan S; Mecitoglu, Idris; Tanyeli, Cihangir; Gülbeyaz, Volkan (Elsevier BV, 1996-12)
New catalysts have been prepared from (S)- and (R)- proline and the asymmetric borane reduction of prochiral ketones using these catalysts has been studied. The secondary alcohols were obtained in 76-95% yield with 57-96% enantiomeric excesses. Copyright (C) 1996 Elsevier Science Ltd
Citation Formats
A. Ciftci, D. VARIŞLI, K. C. Tokay, N. A. Sezgi, and T. Doğu, “Dimethyl ether, diethyl ether & ethylene from alcohols over tungstophosphoric acid based mesoporous catalysts,” CHEMICAL ENGINEERING JOURNAL, pp. 85–93, 2012, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/32042.