Role of the surface intermediates in the stability of basic mixed oxides as catalyst for ethanol condensation

Abstract

The ethanol condensation catalyzed by mixed oxides is studied in this work, considering not only the activity but also the stability of these materials. Concerning to the activity, different weight hourly space velocities (WHSV) were tested, obtaining the highest conversion and 1-butanol selectivity with Mg-Al, mainly at 673 K and a WSHV of 7.9 h−1. On the other hand, dehydration products, observed with Mg-Zr in relevant amounts, limit the results obtained with this material. Deactivation studies were carried out by combining the measurement of reactant and products in the gas phase and in the catalytic surface using spectroscopic techniques (DRIFT). Good stability was observed with both materials at low temperatures (lower than 673 K), whereas at the highest one, Mg-Zr suffers relevant deactivation justified by the permanent adsorption of aldehydes and oxygenated oligomers on the active sites. It has been demonstrated that Mg-Al mixed oxides are promising catalyst for 1-butanol production from ethanol not only in terms of activity, but also in terms of catalyst stability.