Amino acid (histidine) modified Pd/SiO2 catalyst with high activity for selective hydrogenation of acetylene

Suppressing the excessive hydrogenation capacity of palladium has great significance for selective hydrogenation of acetylene. Herein, an amino acid (histidine or His in abbreviation) modified Pd/SiO2 catalyst (Pd-His/SiO2) for selective hydrogenation of acetylene was prepared by incipient wetness impregnation, followed by hydrogen reduction at 240 °C. The intense interaction between Pd and histidine greatly affects the structure and properties of Pd-His/SiO2. The Pd nanoparticles are highly dispersed on the support with an average diameter of 1.0 nm and positively charged. The use of histidine weakens the adsorption of acetylene and ethylene on the metal. Especially, the adsorption of di-σ-bonded ethylene is significantly impaired on the catalyst, which is beneficial to improve the ethylene selectivity. The conversion of acetylene is up to 100.0 % at 160 °C on Pd-His/SiO2 while the ethylene selectivity reaches 81.5 %. A 50-hour test at 160 °C confirms the good stability of Pd-His/SiO2.