Role of surface intermediates in the deactivation of MgZr mixed oxides in acetone self-condensation: A combined DRIFT and ex situ characterization approach

• Deactivation mechanism in acetone self-condensation conditioned by reaction temperature.
• Low temperatures: strong adsorption of reaction products. Deactivation mainly affects to the C9/C6 ratio.
• At temperatures below to 700 K, the loss of activity can be minimized by tuning other reaction conditions.
• At high temperature: stronger and permanent deactivation due to the formation of coke deposits.

The role of the adsorbed reactants and intermediates on the performance and deactivation behavior of MgZr mixed oxides as acetone self-condensation catalysts is studied in this work. DRIFT spectroscopy was used for identifying the adsorbed species and following their evolution during both acetone self-condensation reaction and thermo-desorption of pre-adsorbed reactants and products. The evolution of these species and the results of the characterization (nitrogen physisorption, temperature-programmed oxidation, and catalyst leaching) of catalysts samples taken in a continuous reactor at different temperatures (523, 623, and 723 K) and times on stream allow to determine that two concomitant deactivation causes are present in this reaction: the strong adsorption of dimers and trimers on the catalyst surface (especially important at the lowest temperature) and the formation of heavy condensation products physically deposited on the catalyst surface (more relevant at the highest temperature).

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