Stereo- and Chemoselective Character of Supported CeO2 Catalysts for Continuous-Flow Three-Phase Alkyne Hydrogenation

TiO2-, Al2O3-, and ZrO2-supported CeO2 catalysts with different Ce loadings were prepared by wet impregnation of the carriers with an acidified solution of cerium ammonium nitrate. The calcined catalysts were characterized by bulk and surface-sensitive techniques, which included microcalorimetry, and evaluated in the three-phase hydrogenation of alkynes under continuous-flow conditions at variable temperature (293-413 K) and pressure (1-90 bar). A number of acetylenic compounds, which contain terminal or internal triple bonds, conjugated unsaturations, and additional functionalities, were systematically assessed. The results revealed the full stereo-and chemoselective character of the ceria catalysts, which outperform the wellknown Lindlar catalyst, and open promising perspectives for the revolutionary use of a cost-effective oxide for the production of olefinic compounds in the vitamin and fine chemical industries.