Behavior of CZZr/S Catalysts on the Direct Synthesis of DME from CO2 Containing Feeds

Abstract

The catalytic behavior of a CuO-ZnO-ZrO₂/SAPO-18 (CZZr/S) catalyst on the direct synthesis of DME for different feeds of H₂+CO+CO₂ has been studied in runs carried out in a fixed bed isothermal reactor. The effect of the operating conditions (temperature, pressure, H₂/CO_x ratio and time on stream), and especially of CO₂ concentration in the feed on the conversion of CO_X (CO₂+CO), product yield and selectivity, as well as on the coke content, responsible for deactivation, have been quantified. With this catalyst, at 275 °C, moderate typressure of 30 bar and space time of 10.18 g_cath(mol_C)^-1, CO_X conversion of 0.28 and oxygenates selectivity (DME + MeOH) over 99 % can be obtained from feeds with a CO₂/CO_X ratio of 0.25. The presence of CO₂ in the feed limits coke formation, and therefore, attenuates the deactivation of the catalyst.