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

Realizingthe potential benefits of nanoscale metal catalysts requireshighly dispersed active sites and control of their local environment.Herein, we develop a catalyst synthesis route for manipulating thelocal environment of highly dispersed metal-active sites via the targeteddeposition of Pd near highly dispersed ZrO x on ZSM-5 zeolite using electrostatic interactions. The formed heteroatomPd-ZrO x in zeolite catalysts is characterizedby scanning transmission electron microscopy (STEM), in situ infrared spectroscopy, temperature-programmed desorption (TPD) ofO(2), and temperature-programmed surface reaction (TPSR)of CH4. The combination of diverse characterization resultsdemonstrates the heteroatom Pd-ZrO x speciesrendering a higher dispersion and lower oxygen coordination of Pdspecies, appropriately tuning the strength of Pd-O bonds, andproviding abundant active oxygen species to accelerate the dissociationof CH4. Therefore, the catalytic performance of Pd speciesis effectively enhanced with the lowest temperature of 90% CH4 conversion decreasing from 390 degrees C (without ZrO x ) to 340 degrees C. Our work provides a strategy ofengineering to anchor highly dispersed noble metal species and regulatethe local environment to tune catalytic properties.

Automated summary

Realizing the potential benefits of nanoscale metal catalysts requires controlling their local environment and achieving highly dispersed active sites. In this study, we developed a catalyst synthesis route that targets the deposition of Pd near highly dispersed ZrOx on ZSM-5 zeolite using electrostatic interactions. The heteroatom Pd-ZrOx species formed in the zeolite catalysts were characterized by various techniques, revealing higher dispersion and lower oxygen coordination of Pd species, which enhanced the catalytic performance with a lower temperature for CH4 conversion. Our work provides a strategy to engineer highly dispersed noble metal species and regulate the local environment for tuning catalytic properties.