Nanocomposites and nanomaterials
Guerbet condensation of ethanol and 1‑butanol over hydroxyapatite nanocatalysts
Zikrata O.V., Larina O.V., Valihura K.V., Kyriienko P.I., Soloviev S.O.
L.V. Pisarzhevskii Institute of Physical Chemistry of the NAS of Ukraine. Prospect Nauki, 31, Kyiv-03028, Ukraine.
E-mail: oksanazikrata@ukr.net

The development of processes for the synthesis of valuable chemicals and fuels from renewable raw materials is an important area of research in sustainable chemistry. The unsaturated hydrocarbons and C4+ oxygenates such as 2-ethyl-1-hexanol (2-EH) can be obtained by successive vapor-phase Guerbet condensation of ethanol (EtOH) and 1-butanol (BuOH). Mg-Al oxide systems, zeolites and hydroxyapatites (HAP) are active catalysts for the process due to its acid-base properties.
To regulate acid-base properties of Ca-containing HAP catalysts during the synthesis, a partial substitution of Ca2+ ions by Mg2+ and Sr2+ in the HAP crystal structure are used in present work. The samples were characterized by XRD, SEM, EDX, XPS, FTIR and NMR, and TPD of NH3 and CO2. It is established that the partial replacement of Ca2+ ions by Mg2+ and Sr2+ in the HAP structure leads to deformation of its crystal lattice and to change in the number and strength of the surface acid and base sites of the. The high selectivity values for BuOH and C4+ oxygenates (57 and 79 %) and for 2-EH (62 %) are achieved over 2.5Mg-HAP at 300 °C due to higher number of acid sites of the surface. It also revealed an advanced resistance to deactivation during time-on-stream. Thus, Ca(Mg)-HAP nanosystems are promising catalysts for sustainable production of industrially important higher linear and branched alcohols from reducing raw materials.

1.	Zikrata O. V., Larina O.V., Valihura K. V., Kyriienko P. I., Balakin D. Yu., Khalakhan I., Veltruská K., Krajnc A., Mali G., Soloviev S. O., Orlyk S. M. Successive Vapor-Phase Guerbet Condensation of Ethanol and 1‑Butanol to 2‑Ethyl-1-hexanol over Hydroxyapatite Catalysts in a Flow Reactor // ACS Sustainable Chem. Eng. – 2021. – 9, N 51. – P. 17289-17300.