Authors: Peinado, C; Liuzzi, D; Ladera-Gallardo, RM; Retuerto, M; Ojeda, M; Pena, MA; Rojas, S
Sci Rep. vol: 10. page: 2045-2322.
Date: may-22. 2020.
Dimethyl ether (DME) is an advanced second-generation biofuel produced via methanol dehydration over acid catalysts such as gamma -Al2O3, at temperatures above 240 degrees C and pressures above 10bar. Heteropolyacids such as tungstosilicic acid (HSiW) are BrOnsted acid catalysts with higher DME production rates than gamma -Al2O3, especially at low temperatures (140-180 degrees C). In this work, we show that the performance of supported HSiW for the production of DME is strongly affected by the nature of the support. TiO2 and SiO2 supported HSiW display the highest DME production rates of ca. 50 mmol(DME)/h/g(HSiW). Characterization of acid sites via H-1-NMR, NH3-isotherms and NH3-adsrobed DRIFT reveal that HSiW/X have BrOnsted acid sites, HSiW/TiO2 showing more and stronger sites, being the most active catalyst. Methanol production increases with T until 200 degrees C where a rapid decay in methanol conversion is observed. This effect is not irreversible, and methanol conversion increases to ca. 90% by increasing reaction pressure to 10bar, with DME being the only product detected at all reaction conditions studied in this work. The loss of catalytic activity with the increasing temperature and its increasing with reaction pressure accounts to the degree of contribution of the pseudo-liquid catalysis under the reaction conditions studied..