Synthesis of Heteroatom Pd-ZrO_x Species on Zeolite for Complete Methane Oxidation

Abstract

Realizing the potential benefits of nanoscale metal catalysts requires highly dispersed active sites and control of their local environment. Herein, we develop a catalyst synthesis route for manipulating the local environment of highly dispersed metal-active sites via the targeted deposition of Pd near highly dispersed ZrO x on ZSM-5 zeolite using electrostatic interactions. The formed heteroatom Pd-ZrO x in zeolite catalysts is characterized by scanning transmission electron microscopy (STEM), in situ infrared spectroscopy, temperature-programmed desorption (TPD) of O 2 , and temperatureprogrammed surface reaction (TPSR) of CH 4 . The combination of diverse characterization results demonstrates the heteroatom Pd-ZrO x species rendering a higher dispersion and lower oxygen coordination of Pd species, appropriately tuning the strength of Pd−O bonds, and providing abundant active oxygen species to accelerate the dissociation of CH 4 . Therefore, the catalytic performance of Pd species is effectively enhanced with the lowest temperature of 90% CH 4 conversion decreasing from 390 °C (without ZrO x ) to 340 °C. Our work provides a strategy of engineering to anchor highly dispersed noble metal species and regulate the local environment to tune catalytic properties.

Recent advances and future challenges in the catalytic combustion of light hydrocarbon VOCs

“…Tang et al deposited Pd directionally near the highly dispersed ZrO x on ZSM-5 zeolite by electrostatic interactions to eventually form Pd-ZrO x heteroatoms. 69 The results show that Pd species interacts strongly with ZrO x , which highly promotes the complete oxidation of methane. The dispersion state of Pd species could be controlled by adjusting the coverage of ZrO x around Pd.…”