Enhancing water resistance of Pt nanoparticles by tailoring microenvironment of hollow ZSM-5 for efficient benzene oxidation

Abstract

Pt works particularly well as a nanoparticle catalyst in the elimination of atmospheric pollutants, but its application is severely hampered by agglomeration and evenpoisoning in the presence of moisture. Hereby, a novel catalyst Pt@O-ZSM-5@OTS was synthesized to protect Pt, namely 0.5 wt% Pt was integrated into hollow ZSM-5 and subsequently coated hydrophobic octadecyltrichlorosilane (OTS) akin to the waterproof carapace. With the aid of various characterization techniques, the hybrid catalyst induced multiple marked features, such as dual-shell structure, hydrophobic microenvironment, and encapsulated active sites. Under excessively humid conditions (10 vol% H2O), the optimized Pt@O-ZSM-5@OTS2 exhibited a stable benzene conversion efficiency of 100 % for 120 h and outperformed the catalysts reported so far. Even reducing the reaction temperature to 170 °C, the conversion of benzene also reached 85 %, far exceeding the performance of untreated Pt@O-ZSM-5 (∼50 %). The outstanding stability stems from the hollow structure and OTS shell, which not only provide Pt with a protective shield against active site coverage, but also enhance competitive adsorption to benzene. Furthermore, DFT simulations unveil that the hydrophobic OTS shell enhances water resistance, consequently facilitates the oxidative degradation of contaminants at the active site. This work sheds light on novel strategies for the preservation of Pt by hydrophobic zeolite structures, as well as a deeper understanding of the elimination of aqueous VOCs.