Dimethyl Ether Synthesis over Novel Silicotungstic Acid Incorporated Nanostructured Catalysts

Ciftci, Aysegul
Doğu, Timur
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 high DME selectivity values, approaching 100%. The STA-SiO2 mesoporous nanocomposite catalyst having a W/Si atomic ratio of 0.33 showed the highest activity, with a DME selectivity over 99% and a methanol conversion over 60%, at 250 degrees C and at a space time of 0.27 s.g.cm(-3). Effects of W/Si atomic ratio, calcination temperature and the synthesis procedure on the catalytic performance of these novel mesoporous catalytic materials were investigated.


Heteropolyacid Incorporated Bifunctional Core-Shell Catalysts for Dimethyl Ether Synthesis from Carbon Dioxide/Syngas
Core-shell-type catalysts, which are synthesized by encapsulating the Cu-ZnO-Alumina type methanol synthesis catalyst (CZA) by silicotungstic acid (STA)-incorporated mesoporous alumina, were prepared following a hydrothermal route and tested in DME synthesis from syngas and CO2. Activity tests, which were performed in the pressure range of 30-50 bar, and the temperature range of 200-300 degrees C, with different feed compositions (CO2/CO/H-2: 50/-/50, 40/10/50, 25/25/50, 10/40/50) showed that the best-opera...
Dimethyl ether from syngas and effect of CO2 sorption on product distribution over a new bifunctional catalyst pair containing STA@SBA-15
Direct synthesis of dimethyl ether (DME) from syngas was investigated in the presence of a bifunctional catalyst pair containing silicotungstic acid (STA) incorporated SBA-15 (5, 10, 25% by wt. STA) for the in-situ dehydration of synthesized methanol. The methanol synthesis component of this catalyst mixture is a Cu/ZnO-based commercial (HF) catalytic material. The new STA@SBA-15 type solid acid catalysts synthesized in this study indicated ordered mesoporous structures with surface area values in the range...
Conductimetric and potentiometric titration of some hydroxylated cinnamic acids with tetrabutylammonium hydroxide in non-aqueous media
Aktas, AH; Yasar, G; Alsancak, O; Demirci, S (2001-01-01)
In this study, four hydroxycinnamic acids, namely 3,4-dihydroxycinnamic acid, 4-hydroxycinnamic acid, 4-hydroxy -3- methoxycinnamic acid and 4-hydroxy-3,5-dimethoxycinnamic acid, were titrated conductimetrically and potentiometrically using triethylamine and tetrabutylammonium hydroxide in acetonitrile, 2-propanol, and pyridine solvents under a nitrogen atmosphere at 25 degreesC.
Activated carbon-tungstophosphoric acid catalysts for the synthesis of tert-amyl ethyl ether (TAEE)
Obali, Zeynep; Doğu, Timur (2008-05-01)
Catalytic activities of bulk tungstophosphoric acid (HPW) and its supported forms on activated carbon were investigated in the vapor phase etherification reaction of isoamylene with ethanol in a continuous flow reactor. Tungstophosphoric acid (H3PW12O40 center dot 11H(2)O) was supported on activated carbon having a surface area of 796 m(2)/g, at two different loading levels (25% and 31%) by aqueous impregnation technique and the kinetic experiments were done in a temperature range between 353 and 370 K. Sup...
Valence-shell electron energy-loss spectra of formic acid and acetic acid
Ari, T; Guven, MH (2000-01-01)
Gas phase optical absorption spectra of formic acid and acetic acid in the energy ranges 5.0-11.3 and 4.4-11.3 eV, respectively, have been previously recorded. It is generally agreed that of the four successive bands observed in the spectra of these compounds, the first corresponds to n --> pi* transition. However, various assignments have been proposed for the following three bands. In the present study, electron energy-loss spectra of formic acid and acetic acid vapours at 70 eV impact energy and 0 degree...
Citation Formats
A. Ciftci, D. VARIŞLI, and T. Doğu, “Dimethyl Ether Synthesis over Novel Silicotungstic Acid Incorporated Nanostructured Catalysts,” INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING, pp. 0–0, 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/56051.