Plant-Mediated Synthesis of Pd Catalysts toward Selective Hydrogenation of 1,3-Butadiene: The Effect of Halide Ions

Pd catalyst is most widely used in the selective reaction of 1,3-butadiene hydrogenation. To improve the butenes selectivity, a series of biogenic Pd/gamma-Al2O3 catalysts were prepared by adding different halide ions. The catalyst obtained by adding 0.1 mM KBr exhibited the best catalytic performance, and the selectivity was remarkably enhanced from 57.6% to 80.1% with 100% conversion at 35 degrees C when compared with the catalyst without halide ions. In addition, it presented desired stability within 24 h. To investigate the influence of halide ions on the catalytic performance, prepared Pd catalysts were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, hydrogen temperature-programmed reduction, and ultraviolet-visible diffuse reflectance spectroscopy. The results revealed that particle size, Pd-0/Pd2+, and hydrogen spillover caused by halide ions are closely related with catalytic performance.