Sorption Enhanced DME Synthesis (SEDMES) is a feasible approach to increase DME production from CO2-rich syngas.

No abstract

Dimethyl ether (DME) is an advanced second-generation biofuel produced via methanol dehydration over acid catalysts such as γ-Al 2 o 3 , at temperatures above 240 °C and pressures above 10 bar. Heteropolyacids such as tungstosilicic acid (HSiW) are Brønsted acid catalysts with higher DME production rates than γ-Al 2 o 3 , especially at low temperatures (140-180 °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. TiO 2 and SiO 2 supported HSiW display the highest DME production rates of ca. 50 mmol DME /h/ g HSiW. Characterization of acid sites via 1 H-NMR, NH 3-isotherms and NH 3-adsrobed DRIFT reveal that HSiW/X have Brønsted acid sites, HSiW/TiO 2 showing more and stronger sites, being the most active catalyst. Methanol production increases with T until 200 °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 10 bar, 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.

AbstractThe biomass-to-liquid (BtL) process is a promising technology to obtain clean, liquid, second-generation biofuels and chemicals. The BtL process, which comprises several steps, is based upon the gasification of biomass and the catalytic transformation of the syngas that is obtained via the Fischer-Tropsch synthesis (FTS) reaction, producing a hydrocarbon pool known as syncrude. The FTS process is a well-established technology, and there are currently very large FTS plants operating worldwide that produce liquid fuels and hydrocarbons from natural gas (NG) (gas-to-liquids, GtL process) and coal (coal-to-liquids, CtL process). Due to the limited availability of local biomass, the size of the BtL plants should be downscaled compared to that of a GtL or CtL plant. Since the feasibility of the XtL (X refers to any energy source that can be converted to liquid, including coal, NG, biomass, municipal solid waste, etc.) processes is strongly influenced by the economies of scale, the viability of small-scale BtL plants can be compromised. An interesting approach to overcome this issue is to increase the productivity of the FTS process by developing reactors and catalysts with higher productivities to generate the desired product fraction. Recently, by integrating membrane reactors with the FTS process the gas feeding and separation unit have been demonstrated in a single reactor. In this review, the most significant achievements in the field of catalytic membrane reactors for the FTS process will be discussed. Different types of membranes and configurations of membrane reactors, including H2O separation and H2-feed distribution, among others, will be analyzed.

Two types of active sites for CO dissociation exist in Ru particles. Step-edge sites deactivate during reaction.