The influence of different promoter oxides on the functionality of hybrid CuZn-ferrierite systems for the production of DME from CO2-H2 mixtures

Abstract

In this work the one pot production of dimethylether (DME) by catalytic hydrogenation of carbon dioxide has been studied. The catalytic behaviour of the CuZn-ferrierite hybrid system has been assessed, considering the influence of five different oxides promoters (i.e., ZrO2, CeO2, La2O3, Al2O3, Ga2O3) both on the physico-chemical properties (i.e., surface area, pore volume, copper surface area and dispersion, metal-oxide distribution, acid-base capacity) and on the activity-selectivity pattern. The reaction was carried out in a fixed bed reactor, by feeding CO2 and H2 in the molar ratio 1: 3. The CuZn-FER catalysts doped with Zr, Al or Ga showed a similar behaviour in the DME production, while Ce and La exhibited an inadequate functionality as oxide promoters, mainly evidencing a higher activation energy on the CO2 activation path. The final DME productivity resulted to be driven not so much by specific metallic properties, rather by the presence of an adequate surface balance of acid-base sites that, in a different way, shift the reactions of the global process towards the equilibrium value.