Pd/Ga2O3–Al2O3 catalysts for the selective liquid-phase hydrogenation of acetylene to ethylene

The structure of Ga 2 O 3 –Al 2 O 3 supports and Pd/Ga 2 O 3 –Al 2 O 3 catalysts and the performance of these catalysts in liquid-phase acetylene hydrogenation have been investigated. The deposition of Ga(NO 3 ) 3 onto Al 2 O 3 by impregnation followed by calcination of the impregnated support at 600°C yields γ-Ga 2 O 3 –Al 2 O 3 solid solutions containing up to 50 wt % Ga 2 O 3 . X-ray diffraction characterization of model palladium catalysts and their temperature-programmed reduction with hydrogen have demonstrated that, while palladium in Pd/Ga 2 O 3 is in the form of a Pd 2 Ga alloy, in the Pd/γ-Ga 2 O 3 –Al 2 O 3 catalyst there is no direct interaction between PdО and Ga 2 O 3 particles and palladium is in the monometallic state. The introduction of 10–20 wt % gallium oxide into Al 2 O 3 lowers the activity of the supported palladium catalyst relative to that of the initial Pd/Al 2 O 3 but increases the ethylene yield by enhancing the ethylene formation selectivity.