A novel UiO-66 encapsulated 12-silicotungstic acid catalyst for dimethyl ether synthesis from syngas

Dimethyl ether (DME) has received great attention as a promising clean fuel and industrially important intermediate. Tremendous efforts have been made to develop highly active and stable catalysts for DME production. Here, we present the first example of the application of metal-organic framework (MOF) catalyst in DME synthesis from syngas. A Zr-MOF (UiO-66) was selected as the catalyst host and support owing to its exceptionally high stability and porosity. UiO-66 was firstly functionalized by silicotungstic acid (H4SiW12O40, STA) via a one-pot synthesis method and then loaded with Cu by a facile solid grinding method. The prepared catalysts were characterized using XRD, TGA, FT-IR, N-2 adsorption and TEM. The high porosity and thermal stability of acidified UiO-66 were maintained after 15% wt STA incorporation without any destruction of the Keggin structure of STA. The catalyst was tested for one step DME synthesis from syngas, showing higher DME selectivity and space-time yield than control catalysts. The superior activity of Cu/STA-UiO was attributed to the uniform dispersion of active centres with close intimacy and high density of Bronsted acid sites, as well as strong metal support interaction between Cu and Zr oxide SBU evidenced by XPS analysis.