Hollow ZSM-5 zeolite encapsulated Ag nanoparticles for SO2-resistant selective catalytic oxidation of ammonia to nitrogen

Hollow ZSM-5 encapsulating Ag particles (Ag/ZSM-5-OH) have been successfully synthesized, characterized and tested in NH3-SCO reaction. In comparison with Ag/Al2O3 and Ag/ZSM-5-OH, Ag/ZSM-5 catalyst displayed the lowest T-100 (110 degrees C), much higher TOF and the lowest E-a. Although fresh Ag/ZSM-5-OH catalyst showed the relatively low NH3 conversion, its reaction cycles stability was significant higher than that of Ag/Al2O3 and Ag/ ZSM-5 catalysts. The hollow structure of ZSM-5 zeolite could prevent sintering and/or leaching of Ag particles during NH3 oxidation process. Zeolite membrane formed during dissolution-recrystallization process in the surface of hollow ZSM-5 could offer good separation properties for SO2. So SO2 did not diffuse into the hollow structure to be poisoned Ag catalyst, finally induced the outstanding SO2/H2O resistance.