Nanocomposites and nanomaterials
Catalytic properties of Mg-Al-Ce oxide systems in gas phase conversion of ethanol to 1-butanol in a flow reactor
Valihura K.V., Larina O.V., Soloviev S.O.
L.V. Pisarzhevsky Institute of Physical Chemistry of the NAS of Ukraine.
Prospect Nauky, 31, Kyiv-03039, Ukraine.
E-mail: karina.valigura@ukr.net

Guerbet condensation is of high importance and interest for the production of valuable products from bioethanol. This process consists of doubling of the carbon chain including dehydrogenation, aldol condensation, dehydration and reduction steps [1]. The investigation of catalysts containing proper balance of acid-base active sites for all steps is required. One of the most promising catalysts for the gas phase condensation of ethanol are Mg-Al-oxide systems, which acid-base properties could be regulated by introduction of modifying additives [2].
Mg-Al-Ce hydrotalcites with Mg/(Al+Ce) ratio from 1 to 4 were synthesized using co-precipitation method. The hydrotalcite structure provides high dispersion of the oxide phases after treatment at 873 K, which was confirmed by XRD, SEM/EDX and NMR. XPS data revealed the presence of Ce3+ and Ce4+ containing phases. The acid and base sites of the Mg-Al-Ce oxide samples have been studied by a quasi-equilibrium thermal desorption of NH3 and CO2, and acid/base capacity ratio (ABCR) is used as a characteristic. Activity and selectivity of the catalysts in the ethanol-to-1-butanol process are determined by both the nature of acid/base sites and acid/base capacity ratio. For effectiveness of the target process, the ratio of the catalyst oxide components (Mg, Al, Ce) should provide ABCR close to 3. The highest 1-butanol yield 11.0% at 548 K and TOS = 0.5 h is achieved over Mg-Al-Ce oxide catalyst with Mg/(Al+Ce) = 4, but the activity towards 1-butanol formation is decreased in time rapidly. The highest selectivity 68% is reached over Mg-Al-Ce oxide catalyst with the ratio of Mg/(Al+Ce) = 2. The catalyst provides 1-butanol yield of 9.8% at 548 K and TOS = 0.5 h, and 4.6% at TOS = 4 h. 

1.	Valihura K.V., Soloviev S.O. Catalysts for vapor phase condensation of С1-С4 alcohols with carbon chain elongation // Catalysis and petrochemistry.-2020.-29.-P. 1039-1052.32–51.
2.	Larina O.V., Valihura K.V., Čendak T., Effect of the cerium modification on acid-base properties of Mg-Al hydrotalcite-derived oxide system and catalytic performance in ethanol conversion // React. Kinet. Mech. Catal.-2021.-132.-P. 359–378.