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...
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...
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.
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.