DME production by CO2 hydrogenation: Key factors affecting the behaviour of CuZnZr/ferrierite catalysts

The direct hydrogenation of CO2 into dimethyl ether (DME) has been studied in a fixed bed reactor (T-R: 220-260 degrees C; PR: 5.0 MPa; GHSV: 8800 NL/Kg(cat)/h), in presence of CuZnZr-ferrierite hybrids combining in a single pellet the metal-oxide sites responsible for CO2 activation/hydrogenation and the acidic sites for MeOH dehydration to DME. Two different preparation methods (Le., impregnation and gel-oxalate coprecipitation) have been adopted to evaluate how the metal loading and element interdispersion over the bidimensional lamellar structure of the ferrierite affect the nature and morphology of the active sites. A CuZnZr:FER weight ratio greater than 1 allowed to obtain the best activity-selectivity pattern on the co-precipitated samples, attaining a CO2 conversion of 23.6% at 260 degrees C and a cumulative MeOH/DME yield of ca. 15%. The effects of experimental conditions on the activity-selectivity pattern were also investigated, to disclose the preferential reaction pathways leading to higher DME selectivity. (C) 2016 Elsevier B.V. All rights reserved.