In situ confinement of PdO within zeolite as robust adsorbent/catalyst for toluene elimination

Abstract

Herein, 1 wt% PdO nanoparticles were in situ confinement within HZSM-5 by one-pot hydrothermal method. Characterizations confirmed that Pd(en)22+ were first loaded on small pieces HZSM-5, after small HZSM-5 self-assembly aggregated into larger pieces, Pd active sites were sandwiched in the HZSM-5 crystal with small particle size and high dispersion. The sample was thermal-stable after calcination or utilization at 800 °C, which guaranteed Pd@Z5 a robust bi-functional adsorbent/catalyst for VOCs elimination. The adsorption capacity reached 58.5 mg/g in 100 ppm toluene/humid air, and the adsorption efficiency was not affected by 100 ∼ 500 ppm toluene. Pd@Z5 was stable for toluene oxidation in switching temperatures, PdO size was almost unchanged under 800 °C. Conversely, PdO impregnated directly on ZSM-5 suffered significant sintering after calcination at 800 °C, leading PdO nanoparticles decomposed and aggregated into larger nanoparticles. The adsorption capacity of Pd/Z5-800 declined by 40% and its T90 increased by 26 °C compared to Pd/Z5. Furthermore, Pd@Z5 showed better resistance to SO2 than Pd/Z5, demonstrating the sample had great potential for practical application.