N-containing silane coupling agent-assisted synthesis of highly dispersed and stable PdC phase for semi-hydrogenation of acetylene

• Stable PdC phase was successfully synthesized. • The stable PdC phase is different with the thin PdC layer generated in situ . • The stable PdC phase displays better catalytic properties than PdAg. A highly dispersed and stable PdC phase supported on α-Al 2 O 3 for semi-hydrogenation of acetylene was prepared using N-containing silane coupling agent as a modifier. The catalyst exhibited as much as 15% higher ethylene selectivity than traditional PdAg alloy with full acetylene conversion under 240 °C and performed longer stability within 200 h tolerance test. Characterization results reveal that the excellent ethylene selectivity is mainly derived from the special PdC phase nanoparticle structure with lattice relaxation and distortion. This unique structure makes the catalyst perform weaker adsorption of ethylene, have more abundant spillover hydrogen on the carrier surface and lead a strong interaction between the Pd nanoparticles and surface. Experimental results and DFT calculations have shown the PdC phase is a more promising structure than the commonly used PdAg alloy.