molecules Review CO2 Recycling to Dimethyl Ether: State-of-the-Art and Perspectives Enrico Catizzone 1,* ID , Giuseppe Bonura 2 ID , Massimo Migliori 1, Francesco Frusteri 2 and Girolamo Giordano 1 1 Department of Environmental and Chemical Engineering, University of Calabria, Via P. Bucci, 87036 Rende (CS), Italy;
[email protected] (M.M.);
[email protected] (G.G.) 2 CNR-ITAE “Nicola Giordano”, Via S. Lucia Sopra Contesse 5, 98126 Messina, Italy;
[email protected] (G.B.);
[email protected] (F.F.) * Correspondence:
[email protected]; Tel.: +39-098-449-6669 Received: 13 November 2017; Accepted: 22 December 2017; Published: 24 December 2017 Abstract: This review reports recent achievements in dimethyl ether (DME) synthesis via CO2 hydrogenation. This gas-phase process could be considered as a promising alternative for carbon dioxide recycling toward a (bio)fuel as DME. In this view, the production of DME from catalytic hydrogenation of CO2 appears as a technology able to face also the ever-increasing demand for alternative, environmentally-friendly fuels and energy carriers. Basic considerations on thermodynamic aspects controlling DME production from CO2 are presented along with a survey of the most innovative catalytic systems developed in this field. During the last years, special attention has been paid to the role of zeolite-based catalysts, either in the methanol-to-DME dehydration step or in the one-pot CO2-to-DME hydrogenation. Overall, the productivity of DME was shown to be dependent on several catalyst features, related not only to the metal-oxide phase—responsible for CO2 activation/hydrogenation—but also to specific properties of the zeolites (i.e., topology, porosity, specific surface area, acidity, interaction with active metals, distributions of metal particles, .