Recovery of Au Nanoparticles via High‐Solubility Carboxylic Starch and its Significantly Improved Catalysis of Propylene Epoxidation

Abstract Recovery of Au nanoparticles (Au NPs) catalysts via bioreduction method has attracted much attention due to its cost‐effective and eco‐friendly. However, it is a great challenge to recover Au NPs by starch due to its poor solubility. Herein, a novel biomolecule, carboxyl corn starch (CCS), exhibited high solubility and low viscosity is successfully fabricated and utilized to reduce HAuCl 4 in the homogeneous phase environment. Effects of CCS concentration on the structure and performances of Au NPs and its loading in the TS‐1 support (Au/TS‐1) are investigated. The results reveal that both the particle size and Au NPs recovery rate increased with the increase of CCS concentration, while the BET data of Au/TS‐1 decreased. The Au/TS‐1 catalyst achieved 353.01 m 2 g −1 surface area and 0.293 cm 3 g −1 pore volume with 2.0 ± 0.3 nm average diameter of loaded Au NPs. When this catalyst is employed to catalyze the vapor phase propylene epoxidation with H 2 /O 2 mixture, the propylene conversion rate (19.2%) achieved 67% and 5.8 fold increases when in data reported (11.5%) and soluble starch are used as the control, respectively. The study develops a green and facile method for Au recovery via carboxyl starch bioreduction and Au/TS‐1 exhibited significantly improves catalysis of propylene epoxidation.